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Generalization

in

matechoice

copying

in

humans

Robert

I

Bowers

Skyler

S

Place

Peter

M

Todd

Lars

Penke

Jens

B

Asendorpf

Behavioral

Ecology

Volume

Issue

January

Pages

Published

October

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Abstract

There

is

much

evidence

that

humans

as

other

species

are

affected

by

social

information

when

making

matechoice

decisions

Witnessing

a

rival

show

interest

in

a

member

of

the

opposite

sex

tends

to

lead

human

observers

of

both

sexes

to

thereafter

rate

that

person

as

more

appealing

as

a

potential

mate

However

how

this

occurs

is

not

well

understood

We

investigate

whether

this

effect

is

specific

to

the

individual

witnessed

or

will

generalize

to

other

potential

mates

with

shared

characteristicsthat

is

whether

humans

exhibit

traitbased

or

just

individualbased

matechoice

copying

We

found

that

whereas

this

kind

of

generalization

did

occur

with

Issue

Section

Original

Articles

Milan

Kundera

describes

it

as

one

of

lifes

great

secrets

women

dont

look

for

handsome

men

they

look

for

men

with

beautiful

women

HoganWarburg

describing

ruff

hens

said

it

somewhat

differently

It

has

been

observed

several

times

that

a

crouching

or

copulating

female

especially

attracts

other

females

and

stimulates

them

to

crouch

also

These

are

expressions

of

violations

of

the

assumption

that

matechoice

decisions

are

made

independently

of

each

other

Gibson

and

Langen

Matechoice

copying

Losey

et

al

Höglund

et

al

Pomiankowski

is

one

way

in

which

this

happens

where

having

been

chosen

as

a

mate

heightens

ones

subsequent

appeal

as

a

mate

among

observing

rivals

Females

of

several

species

have

been

shown

to

utilize

the

mate

choice

of

conspecific

females

to

inform

their

own

mate

search

preferring

chosen

males

over

others

Kunderas

observation

that

humans

are

among

the

species

that

exhibit

matechoice

copying

has

recently

received

experimental

substantiation

Eva

and

Wood

Jones

et

al

Waynforth

Little

et

al

Parker

and

Burkley

but

see

Uller

and

Johansson

for

both

males

and

females

Place

et

al

Whether

a

potential

mate

has

already

succeeded

in

acquiring

a

mate

or

not

is

readily

visible

in

many

species

In

a

competitive

mating

environment

the

mate

choices

of

rivals

may

contain

valuable

information

about

the

quality

of

potential

mates

Gibson

and

Höglund

Nordell

and

Valone

information

that

may

otherwise

be

costly

to

attain

Gibson

et

al

Briggs

et

al

Dugatkin

and

Godin

unreliable

Sirot

Brennan

et

al

difficult

to

ascertain

Goulet

Nordell

and

Valone

or

require

specific

experience

Dugatkin

and

Godin

Amlacher

and

Dugatkin

Vukomanovic

and

Rodd

Furthermore

time

for

mate

choice

may

be

heavily

constrained

putting

pressure

on

quicker

decisions

Höglund

et

al

These

considerations

lead

to

the

expectation

that

animals

may

come

to

exploit

social

information

as

a

quick

low

cost

indication

of

mate

quality

Pomiankowski

Wade

and

PruettJones

Höglund

et

al

either

as

an

alternative

to

assessing

mates

independently

Briggs

et

al

or

as

a

source

of

additional

information

Gibson

and

Bachman

Mery

et

al

If

matechoice

copying

is

a

domainspecific

adaptation

we

expect

the

manner

in

which

the

information

is

utilized

to

match

the

problem

However

there

is

more

that

may

constrain

the

evolution

of

copying

than

function

The

form

of

extant

mechanisms

in

which

context

copying

appears

will

also

have

consequences

The

constraints

that

phylogeny

and

function

separately

place

on

the

evolution

of

copying

both

require

consideration

Though

evolutionary

history

is

difficult

to

know

viable

possibility

is

that

matechoice

copying

is

serially

homologous

to

other

forms

of

learning

The

underlying

mechanism

may

hold

much

in

common

with

other

forms

of

learning

Alternatively

To

illustrate

the

question

suppose

we

change

our

assessment

of

Snow

White

when

we

see

her

courted

by

Prince

Charming

Have

we

learned

something

just

about

her

Or

have

we

incidentally

also

learned

something

about

other

similar

individuals

say

Snow

Grey

who

holds

observable

traits

in

common

with

Snow

White

such

as

pale

skin

or

a

red

bow

in

her

hair

If

an

instance

of

human

matechoice

copying

generalizes

in

this

way

between

individuals

who

are

similar

in

terms

of

their

features

or

traits

it

can

be

termed

traitbased

if

specific

to

the

person

observed

it

is

individualbased

The

distinction

between

individualbased

and

traitbased

matechoice

copying

is

not

always

drawn

Matechoice

copying

has

sometimes

been

assumed

to

be

traitbased

in

discussions

Brown

and

Fawcett

Laland

and

Janik

in

models

Kirkpatrick

and

Dugatkin

Agrawal

despite

that

the

bulk

of

the

empirical

work

had

exclusively

studied

choice

for

the

particular

individuals

observed

with

the

model

mate

chooser

The

possibility

and

significance

of

traitbased

copying

was

discussed

Brooks

before

it

was

observed

White

and

Galef

Brooks

pointed

out

that

matechoice

copying

results

in

cultural

inheritance

of

preference

only

if

it

goes

beyond

the

individual

to

a

lasting

change

in

the

types

of

mates

subsequently

preferred

that

is

only

if

matechoice

copying

is

trait

based

Thus

whether

copying

is

trait

based

or

exclusively

individual

based

can

have

important

consequences

regarding

cultural

evolution

and

sexual

selection

Both

individualbased

and

traitbased

matechoice

copying

have

been

demonstrated

among

animals

of

several

species

see

next

section

In

humans

individualbased

copying

has

been

shown

using

multiple

methods

eg

Jones

et

al

Waynforth

Place

et

al

Given

the

prevalence

of

cultural

learning

in

humans

including

for

features

used

in

mate

selection

Meskó

and

Bereczkei

Wohlrab

et

al

we

may

also

expect

human

matechoice

copying

to

generalize

to

those

with

similar

traits

Generalized

change

of

attractiveness

ratings

has

since

been

found

with

artificial

manipulations

of

eyespacing

Little

et

al

see

DISCUSSION

and

shirt

color

Place

traits

selected

to

be

arbitrary

Here

through

a

series

of

experiments

we

demonstrate

that

given

the

distribution

of

traits

within

an

actual

population

of

mate

seekers

both

males

and

females

fail

to

exhibit

traitbased

matechoice

copying

for

facial

traits

yet

exhibit

it

for

hair

and

clothing

traits

Meanwhile

the

same

participants

with

the

same

stimuli

consistently

showed

individualbased

matechoice

copying

replicating

earlier

findings

Place

et

al

Furthermore

agerelated

individual

differences

appear

in

traitbased

but

not

individualbased

copying

We

find

that

this

pattern

of

social

information

use

suits

how

and

when

the

information

will

be

most

useful

We

begin

by

reviewing

work

on

traitbased

matechoice

copying

in

other

species

and

functional

considerations

from

which

our

predictions

derive

before

describing

the

manipulations

of

matechoice

information

we

use

to

elicit

copying

in

humans

PHYLOGENY

AND

TRAITBASED

MATECHOICE

COPYING

The

question

of

whether

matechoice

copying

generalizes

has

been

addressed

in

previous

studies

of

different

species

Female

quail

Coturnix

coturnix

japonica

show

sexual

preferences

for

males

seen

consorting

with

other

females

Galef

and

White

White

and

Galef

marked

males

with

a

pennysized

red

or

blue

dot

of

dyed

chest

feathers

or

with

the

addition

of

white

feathers

to

the

brown

plumage

of

the

crest

The

colored

dot

was

conspicuous

on

a

cryptic

ground

bird

like

the

quail

but

the

few

white

feathers

in

the

crest

was

chosen

as

a

variant

that

though

unusual

occurs

in

wild

populations

In

both

experiments

females

witnessing

a

male

with

the

added

marking

successfully

courting

other

hens

subsequently

showed

a

preference

for

novel

but

similarly

marked

males

Comparable

demonstrations

were

made

independently

with

species

from

the

same

genus

sailfin

mollies

Poecilia

latipinna

and

guppies

Poecilia

reticulata

Witte

and

Noltemeier

began

with

the

observation

that

female

sailfin

mollies

show

mating

preferences

for

larger

males

Witte

and

Ryan

Females

were

allowed

to

observe

a

rival

affiliating

with

a

smaller

male

while

a

larger

male

remained

alone

Such

social

information

has

been

shown

to

affect

mating

preferences

when

the

choice

is

between

males

of

similar

size

but

between

males

of

substantially

different

size

the

typical

preference

for

larger

males

in

this

species

overrides

the

influence

of

copying

Witte

and

Ryan

Witte

and

Noltemeier

found

however

that

by

lengthening

the

observation

period

to

minutes

vs

minutes

in

previous

studies

the

influence

of

copying

strengthened

such

that

social

information

was

heeded

even

in

conflict

with

native

preferences

When

thereafter

allowed

to

choose

between

the

males

their

subjects

more

often

chose

the

smaller

Of

especial

relevance

to

the

present

question

when

the

same

females

were

subsequently

given

similar

matechoice

dilemmas

between

novel

males

that

differed

in

size

even

after

a

delay

of

some

weeks

they

again

tended

to

choose

the

smaller

male

Similarly

female

guppies

show

initial

preferences

for

males

with

bright

Godin

et

al

Experiment

Females

observed

relatively

drably

colored

males

affiliating

with

females

and

more

brightly

colored

males

alone

This

procedure

has

been

shown

to

be

capable

of

reversing

initial

speciestypical

preferences

Dugatkin

and

Godin

When

tested

with

different

males

a

day

later

these

females

showed

a

preference

for

drabber

males

over

brighter

males

In

both

the

mollies

and

the

guppies

an

initial

preference

was

overshadowed

by

conflicting

social

information

and

the

social

information

manipulation

had

affected

not

only

preferences

for

individual

mates

but

also

for

characteristics

of

mates

Zebra

finch

Taeniopygia

guttata

females

exposed

to

paired

and

unpaired

males

subsequently

preferred

novel

males

with

leg

bands

Swaddle

et

al

or

artificial

crest

adornments

Kniel

et

al

of

the

color

of

the

paired

males

Female

fruit

flies

Drosophila

melanogaster

exhibit

both

individualbased

Mery

et

al

Experiment

and

traitbased

Experiment

copying

Given

the

choice

between

males

dusted

with

different

colors

females

preferred

those

of

the

color

of

a

similarly

dusted

male

they

had

previously

witnessed

being

chosen

by

another

female

In

all

the

above

species

matechoice

copying

appears

to

be

trait

based

generalizing

to

individuals

with

perceptible

characteristics

similar

to

those

whose

mating

successes

had

been

observed

We

believe

this

to

be

an

exhaustive

list

of

published

studies

that

address

this

matter

to

our

knowledge

no

examples

of

the

converse

where

generalization

to

similar

others

is

lacking

have

been

documented

Like

the

larger

list

of

species

that

evidence

individualbased

matechoice

copying

the

above

species

comprise

a

diverse

selection

of

animals

in

terms

of

phylogeny

ecology

and

mating

behavior

There

is

no

apparent

commonality

among

them

in

terms

of

mating

system

or

parental

investment

Guppies

are

polygynous

zebra

finch

are

socially

monogamous

Parental

investment

in

the

fly

is

limited

to

choice

of

egg

laying

site

guppies

and

mollies

are

viviparous

and

invest

no

parental

care

both

bird

species

nest

and

hatch

their

eggs

but

with

quail

only

females

care

for

hatchlings

Mills

et

al

whereas

among

zebra

finch

care

for

young

is

provided

by

both

parents

Swaddle

et

al

and

for

considerably

longer

So

far

ecology

appears

to

be

a

poor

predictor

of

traitbased

copying

That

all

species

that

have

been

tested

so

different

from

each

other

show

the

same

pattern

may

suggest

that

traitbased

matechoice

copying

is

adaptive

use

of

social

information

across

a

broad

range

of

mating

contexts

Alternatively

the

apparent

ubiquity

of

traitbased

copying

may

be

due

not

to

functional

but

phylogenetic

constraints

a

broad

commonality

in

underlying

cognition

All

these

animals

learn

by

association

and

as

noted

above

a

common

quality

of

learning

is

generalization

Note

that

traitbased

copying

may

be

a

consequence

of

FUNCTION

AND

TRAITBASED

MATECHOICE

COPYING

Individualbased

matechoice

copying

carries

a

possibly

costly

consequence

It

places

mate

seekers

especially

in

the

thick

of

competition

Brennan

et

al

specifically

leading

them

to

choose

mates

that

have

already

been

chosen

by

others

Whether

this

imparts

a

substantial

cost

and

to

what

extent

depends

on

many

factors

of

the

matechoice

environment

In

many

species

competition

often

leads

to

intrasexual

conflict

which

can

have

serious

survival

costs

Furthermore

particularly

among

monogamous

species

the

taken

mate

may

often

be

content

with

the

current

situation

and

resist

the

new

suitor

leading

to

wasted

mating

effort

Traitbased

copying

does

not

necessarily

bear

these

costs

so

squarely

as

it

leads

the

mate

seeker

to

the

broader

category

of

the

taken

plus

those

similar

to

the

Swaddle

et

al

A

convincing

case

has

been

made

that

individualbased

matechoice

copying

is

good

usage

of

social

information

in

a

variety

of

mating

environments

Wade

and

PruettJones

Gibson

and

Höglund

Nordell

and

Valone

Is

generalization

of

the

effect

to

similar

individuals

traitbased

matechoice

copying

likewise

adaptive

It

may

be

so

if

there

are

perceptible

traits

that

correlate

with

both

mate

choice

and

mate

quality

Bradbury

That

is

there

must

be

something

to

be

able

to

generalize

with

respect

to

Though

individualbased

copying

exploits

whatever

direct

correlation

may

exist

between

mate

quality

and

mate

choice

traitbased

copying

relies

on

perceptible

intervening

traits

correlating

with

both

Given

the

expectations

that

mate

choice

and

mate

quality

may

often

correlate

and

that

there

may

be

perceptible

traits

that

correlate

with

each

the

conditions

for

adaptive

traitbased

copying

appear

likely

to

be

met

in

some

cases

But

not

always

If

these

correlations

with

traits

are

low

an

indicator

of

mating

success

may

be

a

poor

cue

to

mate

quality

Consequently

Gibson

et

al

Furthermore

the

choice

reversal

experiments

in

which

copying

disrupts

preference

for

independently

assessed

mates

Dugatkin

and

Godin

Coolen

et

al

Mery

et

al

accentuate

that

copied

preferences

may

counteract

even

native

matechoice

criteria

putative

indicators

of

mate

quality

Furthermore

if

the

correlations

among

mate

choice

mate

quality

and

perceptible

traits

are

appreciable

nonsocial

mechanisms

for

recognizing

the

indicator

eg

innate

recognition

or

individual

learning

may

constitute

better

use

of

available

information

Sirot

Indeed

one

of

the

conditions

for

matechoice

copying

individualbased

or

otherwise

being

adaptive

usage

of

information

is

that

relationship

status

provides

mate

quality

information

that

is

not

fully

captured

by

outward

indicators

This

may

be

because

outward

indicators

of

mate

quality

are

lacking

unreliable

or

difficult

to

discern

or

because

the

information

gained

concerns

qualities

of

the

candidate

not

readily

apparent

in

physical

characteristics

such

Buss

and

Barnes

Howard

et

al

Penke

et

al

Thus

the

functional

significance

of

traitbased

copying

appears

caught

between

exclusive

alternatives

If

perceptible

cues

exist

that

are

good

indicators

of

mate

quality

the

information

is

public

and

social

information

about

others

mate

choices

will

be

superfluous

If

matechoice

copying

is

to

give

mate

seekers

information

about

traits

that

otherwise

require

extended

interaction

to

assess

such

as

behavioral

or

personality

characteristics

then

although

individualbased

matechoice

copying

makes

good

functional

sense

generalizing

to

others

on

the

basis

of

perceptible

traits

may

mislead

Hence

functional

considerations

give

reason

to

not

expect

traitbased

copying

THE

QUESTION

It

appears

that

phylogenetic

and

functional

considerations

give

differing

predictions

on

the

question

of

whether

matechoice

copying

will

generalize

Phylogenetically

incidence

of

matechoice

copying

appears

to

be

spotty

with

more

distant

species

behaving

very

similarly

whereas

nearer

species

differ

Given

that

all

species

in

which

traitbased

copying

has

been

studied

have

evidenced

it

considerations

of

phylogeny

suggest

traitbased

copying

where

there

is

individualbased

copying

As

humans

share

with

these

animals

associative

learning

processes

that

exhibit

generalization

in

other

domains

our

beginning

hypothesis

was

that

humans

will

similarly

exhibit

traitbased

matechoice

copying

In

contrast

considerations

of

function

suggest

that

although

EXPERIMENTS

We

tested

whether

human

observers

judgments

of

appeal

or

attractiveness

of

stimulus

faces

would

be

affected

by

perceptions

of

others

apparent

sexual

interest

to

evince

matechoice

copying

and

further

whether

these

observers

would

generalize

this

change

in

assessment

to

other

people

expressing

shared

physical

traits

traitbased

copying

Videos

of

people

on

real

speeddates

provided

naturalistic

matechoice

information

see

Place

for

additional

control

experiments

We

varied

kinds

of

trait

that

play

a

role

in

natural

mating

circumstances

facial

characteristics

and

culturally

acquired

characteristics

clothing

and

hair

styles

Comparable

experiments

were

conducted

with

each

class

of

trait

with

female

participants

assessing

male

stimuli

and

male

participants

assessing

female

stimuli

Materials

Stimuli

for

all

experiments

were

taken

from

the

Berlin

Speed

Dating

Study

BSDS

Asendorpf

et

al

an

effort

that

involved

systematically

running

and

recording

a

series

of

real

speeddating

sessions

among

single

daters

All

participating

daters

were

individually

photographed

at

the

start

of

the

session

with

neutral

expressions

and

standardized

lighting

conditions

and

then

all

speeddating

interactions

were

videotaped

start

to

end

After

each

interaction

each

dater

decided

whether

they

wanted

to

see

that

person

again

indicated

discretely

on

a

score

card

returned

to

the

organizers

at

the

end

of

the

event

and

in

cases

where

interest

was

mutual

contact

information

would

be

released

Thus

this

decision

had

the

real

consequence

of

allowing

or

disallowing

Asendorpf

et

al

Each

experiment

reported

below

used

fortyeight

silent

video

segments

of

BSDS

speeddating

interactions

Each

video

presentation

showed

both

daters

simultaneously

In

the

experiments

female

subjects

watched

videos

each

featuring

a

different

male

dater

the

target

stimulus

interacting

with

a

different

female

dater

the

model

Each

target

dater

appeared

in

positive

interaction

ie

where

the

model

dater

had

subsequently

indicated

interest

in

the

target

and

negative

interaction

for

a

total

of

videos

Each

female

subject

would

see

of

the

videos

of

each

of

the

male

daters

either

the

positive

or

the

negative

interaction

Frontal

facial

photographs

of

BSDS

daters

were

also

used

including

those

appearing

in

the

videos

other

BSDS

participants

that

appear

in

of

the

videos

shown

and

some

composites

of

faces

from

the

same

stimulus

set

Composites

were

created

using

Adobe

Photoshop

software

This

involved

replacing

some

portion

of

facial

photograph

with

the

corresponding

portion

of

another

as

expounded

below

All

photographs

were

centered

frontal

images

from

the

crest

of

the

head

to

the

base

of

the

neck

taken

on

a

plain

light

background

Facial

expressions

were

neutral

All

stimuli

were

presented

using

DirectRT

software

on

a

desktop

General

subject

characteristics

Heterosexual

students

of

psychology

courses

at

Indiana

University

Bloomington

participated

in

return

for

course

credit

Subjects

were

given

the

opportunity

to

comment

on

the

experiment

in

a

text

box

at

the

end

of

the

session

Roughly

of

subjects

left

a

comment

Data

of

subjects

were

omitted

on

account

of

these

comments

women

who

noted

that

the

men

appeared

too

old

for

them

to

be

interested

from

Experiment

and

in

Experiment

one

subject

who

had

noticed

that

the

images

had

been

manipulated

and

another

who

felt

tricked

These

were

the

only

indications

that

people

sensed

General

design

and

procedure

All

experiments

described

below

follow

the

same

basic

withinsubjects

design

to

simultaneously

answer

questions

Is

there

individualbased

matechoice

copying

Is

there

traitbased

matechoice

copying

Both

questions

are

answered

by

comparing

the

change

in

observers

ratings

of

stimulus

faces

before

and

after

observing

a

speeddate

as

a

consequence

of

the

apparent

success

or

failure

of

the

dater

in

the

interaction

they

observed

If

the

change

in

ratings

of

the

target

faces

shown

receiving

interest

in

the

video

is

higher

than

that

of

target

faces

shown

in

negative

interactions

individualbased

matechoice

copying

is

evidenced

If

the

same

holds

for

the

similartotarget

Subjects

are

first

shown

a

series

of

oppositesex

facial

photographs

one

at

a

time

in

simulated

random

order

These

are

from

categories

target

faces

that

will

be

associated

directly

with

mating

success

information

in

the

videos

faces

that

are

similar

to

the

target

faces

and

control

faces

of

other

BSDS

daters

Subjects

are

asked

to

rate

each

photo

on

two

Likerttype

scales

attractiveness

How

attractive

do

you

find

this

person

and

appeal

as

a

longterm

partner

How

interested

would

you

be

in

this

person

for

a

committed

longterm

relationship

Next

a

series

of

demographic

and

personal

questions

Landolt

et

al

and

an

overall

rating

of

their

own

attractiveness

How

attractive

do

you

think

you

are

After

this

subjects

were

shown

a

video

clip

of

the

speeddating

interaction

for

each

of

pairs

of

daters

Half

of

the

daters

were

shown

in

positive

interactions

half

in

negative

counterbalanced

between

subjects

On

the

screen

below

the

video

were

displayed

the

facial

images

of

the

man

and

woman

in

the

video

one

of

which

was

manipulated

in

Experiment

described

below

After

viewing

the

video

female

subjects

were

asked

Based

on

the

video

you

just

watched

do

you

think

the

woman

was

interested

inattracted

to

the

man

Male

subjects

were

asked

the

corresponding

question

about

the

mans

Analyses

In

Place

et

al

the

analyzed

variable

was

the

subjects

perception

of

interest

between

the

speed

daters

which

is

dependent

on

the

subjects

Although

the

perception

of

interest

may

be

necessary

for

copying

analyzing

our

data

solely

on

the

basis

of

subjects

perceptions

would

make

our

design

quasiexperimental

However

we

can

also

compare

observer

ratings

based

on

the

actual

interest

that

the

daters

themselves

reported

which

is

varied

experimentally

For

all

of

the

experiments

reported

here

we

conducted

separate

analyses

treating

one

or

the

other

of

these

variables

as

independent

the

perceived

interest

in

order

to

replicate

Place

et

al

and

the

actual

interest

to

bolster

that

analysis

with

an

experimental

design

reported

in

Table

Table

Change

in

ratings

longterm

interest

and

attractiveness

for

target

faces

similartotarget

faces

and

control

faces

depending

on

actual

or

perceived

positive

versus

negative

interest

of

model

daters

from

subjects

of

both

sexes

in

all

experiments

Perceived

interest

Actual

interest

Negative

mean

SD

Positive

mean

SD

F

df

Negative

mean

SD

Positive

mean

SD

F

df

Experiment

female

subjects

N

Target

Long

term

Attractiveness

Similartotarget

Long

term

Attractiveness

Control

Long

term

Attractiveness

Experiment

male

subjects

N

Target

Long

term

P

Attractiveness

P

Similartotarget

Long

term

Attractiveness

Control

Longterm

Attractiveness

Experiment

female

subject

N

Target

Long

term

Attractiveness

Similartotarget

Longterm

Attractiveness

Control

Long

term

Attractiveness

Experiment

male

subject

N

Target

Long

term

Attractiveness

Similartotarget

Long

term

Attractiveness

Control

Long

term

Attractiveness

Experiment

female

subjects

N

Target

Long

term

Attractiveness

Similartotarget

Long

term

Attractiveness

P

Control

Long

term

Attractiveness

Matechoice

copying

is

evidenced

where

the

change

in

ratings

is

higher

following

positive

interactions

than

negative

interactions

Significant

increases

are

indicated

by

asterisks

P

P

P

Table

Change

in

ratings

longterm

interest

and

attractiveness

for

target

faces

similartotarget

faces

and

control

faces

depending

on

actual

or

perceived

positive

versus

negative

interest

of

model

daters

from

subjects

of

both

sexes

in

all

experiments

Perceived

interest

Actual

interest

Negative

mean

SD

Positive

mean

SD

F

df

Negative

mean

SD

Positive

mean

SD

F

df

Experiment

female

subjects

N

Target

Long

term

Attractiveness

Similartotarget

Long

term

Attractiveness

Control

Long

term

Attractiveness

Experiment

male

subjects

N

Target

Long

term

P

Attractiveness

P

Similartotarget

Long

term

Attractiveness

Control

Longterm

Attractiveness

Experiment

female

subject

N

Target

Long

term

Attractiveness

Similartotarget

Longterm

Attractiveness

Control

Long

term

Attractiveness

Experiment

male

subject

N

Target

Long

term

Attractiveness

Similartotarget

Long

term

Attractiveness

Control

Long

term

Attractiveness

Experiment

female

subjects

N

Target

Long

term

Attractiveness

Similartotarget

Long

term

Attractiveness

P

Control

Long

term

Attractiveness

Matechoice

copying

is

evidenced

where

the

change

in

ratings

is

higher

following

positive

interactions

than

negative

interactions

Significant

increases

are

indicated

by

asterisks

P

P

P

Mixedlinear

modeling

was

used

for

all

analyses

reported

with

measures

of

multiple

stimuli

as

fixed

effect

and

subjects

as

random

effect

Each

dependent

datum

in

these

tests

is

the

difference

between

initial

and

ultimate

ratings

of

a

stimulus

face

We

test

whether

these

differences

are

more

positive

following

our

manipulation

the

presentation

of

positive

social

information

relative

to

the

analogous

presentation

of

negative

social

information

Male

and

female

samples

are

tested

separately

EXPERIMENT

GENERALIZATION

OF

COPYING

TO

THE

FACIALLY

SIMILAR

As

our

question

was

whether

the

matechoice

copying

effect

would

generalize

to

similar

others

we

needed

to

show

our

subjects

one

persons

mating

success

and

test

them

on

a

different

but

similar

looking

person

But

what

constitutes

similar

looking

When

one

says

that

people

appear

similar

to

each

other

this

is

often

referring

to

their

facial

characteristics

nose

eyes

mouth

and

the

space

between

the

way

these

features

are

configured

with

respect

to

each

other

Thus

we

began

with

manipulations

of

facial

similarity

Methods

A

sample

of

women

years

mean

age

SD

and

a

sample

of

men

years

mean

SD

were

each

subjected

to

a

sexspecific

version

of

Experiment

After

rating

the

initial

set

of

oppositesex

faces

and

completing

the

questionnaire

as

described

above

subjects

were

presented

with

the

following

sequence

of

stimuli

for

each

of

the

stimulus

dating

interactions

They

were

first

shown

a

video

of

a

man

and

woman

on

a

speed

date

and

then

asked

to

rate

the

samesex

model

daters

interest

in

the

oppositesex

target

dater

Subjects

then

rated

Figure

Depiction

of

the

design

of

Experiment

with

an

example

of

stimuli

presented

to

female

subjects

The

faces

along

the

bottom

are

left

to

right

the

target

face

a

control

face

and

the

similartotarget

face

as

described

in

the

text

Figure

Depiction

of

the

design

of

Experiment

with

an

example

of

stimuli

presented

to

female

subjects

The

faces

along

the

bottom

are

left

to

right

the

target

face

a

control

face

and

the

similartotarget

face

as

described

in

the

text

The

target

and

similartotarget

faces

were

manipulated

to

resemble

each

other

by

placing

the

inner

faceforehead

to

chin

cheek

to

cheekof

the

similartotarget

face

onto

the

photograph

of

the

dater

shown

in

the

video

Manipulating

the

target

face

to

resemble

the

similartotarget

face

rather

than

the

converse

afforded

important

advantages

The

primary

motive

was

to

allow

us

to

imbue

multiple

daters

with

the

same

inner

facial

characters

Thus

a

set

of

facial

characters

could

be

associated

with

multiple

instances

of

dating

success

and

this

could

be

compared

with

corresponding

characters

associated

with

multiple

instances

of

dating

failure

One

association

Figure

An

example

of

the

facial

similarity

manipulation

in

Experiment

The

daters

face

panel

not

shown

to

subjects

in

Experiment

is

modified

to

create

the

target

face

panel

by

superimposing

onto

it

the

innerface

oval

region

panel

taken

from

the

similartotarget

face

panel

Figure

An

example

of

the

facial

similarity

manipulation

in

Experiment

The

daters

face

panel

not

shown

to

subjects

in

Experiment

is

modified

to

create

the

target

face

panel

by

superimposing

onto

it

the

innerface

oval

region

panel

taken

from

the

similartotarget

face

panel

The

speeddating

interactions

used

were

divided

into

groups

of

All

targets

in

of

these

groups

ie

target

faces

were

always

shown

in

positive

interactions

for

a

given

subject

counterbalanced

the

target

faces

of

the

other

groups

were

always

in

negative

interactions

All

target

daters

in

each

group

were

associated

with

the

same

similartotarget

face

Thus

each

similartotarget

face

was

similar

to

targets

in

either

positive

or

negative

dating

interactions

Experiment

was

designed

to

be

a

sensitive

test

of

the

hypothesis

that

if

subjects

assess

daters

higher

when

seen

in

positive

interactions

they

will

likewise

increase

their

assessments

of

faces

with

qualities

similar

to

the

successful

daters

First

our

manipulation

of

similarity

was

extreme

the

target

and

similartotarget

faces

having

identical

eyes

nose

mouth

and

configuration

Second

each

similartotarget

face

is

given

multiple

doses

of

concordant

social

information

Both

these

qualities

should

increase

the

likelihood

of

a

traitbased

copying

effect

appearing

if

one

exists

As

a

manipulation

check

we

verified

that

attractiveness

ratings

of

composite

images

used

were

concordant

with

ratings

of

the

original

images

from

which

they

were

created

This

shows

that

subjects

attended

to

the

facial

characteristics

of

the

stimuli

presented

Figure

Results

from

Experiment

for

female

subjects

upper

panel

and

male

subjects

lower

panel

Bars

show

average

SEM

change

in

rating

of

the

classes

of

stimuli

target

similartotarget

or

control

in

terms

of

appeal

as

a

potential

longterm

partner

separately

for

whether

the

subject

had

perceived

the

interaction

as

positive

light

bars

or

negative

dark

bars

Matechoice

copying

is

evidenced

where

the

change

in

ratings

is

higher

when

interest

is

perceivedhere

for

target

stimuli

only

Figure

Results

from

Experiment

for

female

subjects

upper

panel

and

male

subjects

lower

panel

Bars

show

average

SEM

change

in

rating

of

the

classes

of

stimuli

target

similartotarget

or

control

in

terms

of

appeal

as

a

potential

longterm

partner

separately

for

whether

the

subject

had

perceived

the

interaction

as

positive

light

bars

or

negative

dark

bars

Matechoice

copying

is

evidenced

where

the

change

in

ratings

is

higher

when

interest

is

perceivedhere

for

target

stimuli

only

Results

For

both

sexes

the

faces

associated

directly

with

mating

success

information

showed

individualbased

matechoice

copying

replicating

Place

et

al

see

Table

for

all

statistics

That

is

for

both

male

and

female

observers

ratings

of

the

target

faces

shown

in

positive

speeddating

interactions

ie

videos

in

which

the

samesex

target

dater

was

perceived

as

showing

interest

in

the

oppositesex

stimulus

increased

more

than

did

ratings

of

the

shown

in

negative

interactions

This

was

true

for

both

dependent

measures

ratings

of

longterm

romantic

interest

and

attractiveness

Similar

results

were

obtained

when

analyzed

in

terms

of

the

model

daters

actual

reported

interest

as

opposed

to

the

subjects

perception

of

this

interest

The

question

of

primary

interest

was

whether

subjects

would

generalize

their

increased

ratings

to

similar

others

evidencing

traitbased

matechoice

copying

Despite

identical

facial

features

neither

sex

showed

systematic

increases

in

assessment

of

the

similartotarget

faces

neither

for

the

subjects

perceptions

of

daters

interest

nor

for

the

daters

actual

stated

interest

Notice

that

ratings

of

target

stimuli

shown

with

the

videos

even

those

shown

with

negative

interactions

tend

to

increase

between

the

first

and

last

phases

of

the

experiment

whereas

the

ratings

for

the

control

faces

which

appear

in

no

videos

tend

to

decrease

equally

after

both

positive

and

negative

interactions

despite

no

negative

nor

positive

social

information

The

increase

in

the

target

ratings

appears

to

be

due

to

exposure

to

the

behaving

person

in

the

video

negative

change

may

occur

for

stimuli

that

appear

only

in

a

single

repeated

photograph

The

appropriate

comparison

when

assessing

matechoice

copying

thus

is

between

EXPERIMENT

GENERALIZATION

OF

COPYING

TO

THE

SIMILARLY

STYLED

Facial

similarity

is

not

the

only

way

people

can

resemble

each

other

People

vary

in

manner

of

dress

and

in

their

hair

styles

and

these

qualities

appear

to

be

important

to

mate

choice

in

humans

Such

manners

of

similarity

however

differ

from

facial

similarity

in

important

respects

First

while

not

wanting

to

imply

a

strong

dichotomy

the

primary

mode

of

transmission

through

populations

is

different

Facial

qualities

are

inherited

vertically

parent

to

child

qualities

of

style

can

spread

horizontally

within

generational

cohorts

Second

such

conventional

aspects

are

much

more

mutable

On

a

whim

one

can

dress

like

Lena

Lovich

In

the

head

and

shoulders

stimulus

photographs

used

in

our

experiments

there

are

thus

separable

realms

of

traits

we

can

consider

the

inner

face

forehead

to

chin

cheek

to

cheek

and

the

rest

of

the

photograph

which

includes

the

hair

clothes

and

neck

Experiment

showed

that

subjects

while

matechoice

copying

did

not

generalize

this

effect

to

other

people

with

common

inner

facial

cues

Would

our

subjects

show

traitbased

copying

with

nonfacial

cues

Figure

Depiction

of

the

design

of

Experiment

with

an

example

of

stimuli

seen

by

female

subjects

Figure

Depiction

of

the

design

of

Experiment

with

an

example

of

stimuli

seen

by

female

subjects

Methods

A

sample

of

women

years

mean

age

SD

and

a

sample

of

men

years

mean

SD

were

each

subjected

to

a

sexspecific

version

of

Experiment

A

similar

design

to

Experiment

was

used

with

the

key

difference

being

that

similartotarget

faces

now

had

no

cues

taken

from

the

targets

inner

face

but

were

manipulated

to

share

all

cues

external

to

this

region

The

hair

and

clothes

of

each

similartotarget

face

were

the

mirror

image

of

the

target

daters

face

Unlike

in

Experiment

it

was

not

possible

to

show

an

altered

Results

Again

as

shown

in

Figure

see

Table

for

statistics

both

sexes

showed

individualbased

copying

replicating

Place

et

al

In

both

experiments

the

change

in

ratings

for

faces

shown

in

speeddating

interactions

perceived

to

be

positive

were

higher

than

for

those

perceived

to

be

in

negative

interactions

No

differences

appeared

among

the

control

faces

Similar

results

were

obtained

with

analogous

tests

when

analyzed

in

terms

of

the

daters

actual

interest

Figure

Results

from

Experiment

for

female

subjects

upper

panel

and

male

subjects

lower

panel

Bars

show

average

SEM

change

in

rating

of

the

classes

of

stimuli

target

similartotarget

or

control

in

terms

of

appeal

as

a

potential

longterm

partner

separately

for

whether

the

subject

had

perceived

the

interaction

as

positive

light

bars

or

negative

dark

bars

Matechoice

copying

is

evidenced

where

the

change

in

ratings

is

higher

when

interest

is

perceivedhere

for

target

stimuli

and

for

similartotarget

faces

for

male

subjects

Figure

Results

from

Experiment

for

female

subjects

upper

panel

and

male

subjects

lower

panel

Bars

show

average

SEM

change

in

rating

of

the

classes

of

stimuli

target

similartotarget

or

control

in

terms

of

appeal

as

a

potential

longterm

partner

separately

for

whether

the

subject

had

perceived

the

interaction

as

positive

light

bars

or

negative

dark

bars

Matechoice

copying

is

evidenced

where

the

change

in

ratings

is

higher

when

interest

is

perceivedhere

for

target

stimuli

and

for

similartotarget

faces

for

male

subjects

Unlike

in

Experiment

however

here

there

was

evidence

of

traitbased

copying

as

well

Male

subjects

increased

their

relationship

interest

ratings

not

only

of

the

faces

of

successful

individuals

but

also

of

the

similartotarget

faces

associated

with

successful

daters

compared

with

those

associated

with

unsuccessful

daters

These

effects

were

significant

P

for

longterm

interest

and

in

the

predicted

direction

P

for

attractiveness

ratings

see

Table

The

analogous

test

for

the

female

subjects

however

did

not

show

a

significant

difference

obliging

further

investigation

EXPERIMENT

TESTING

FOR

AGE

EFFECTS

AMONG

FEMALES

In

Experiment

evidence

of

traitbased

copying

appeared

among

male

subjects

but

not

females

Such

a

sex

difference

had

not

been

predicted

Post

hoc

analyses

suggested

female

subjects

age

to

be

a

mediating

factor

The

female

subjects

above

the

median

age

of

our

sample

years

did

not

show

the

predicted

difference

among

ratings

of

the

similartotarget

photos

following

positive

interactions

versus

negative

Indeed

for

both

dependent

variables

mean

change

in

ratings

for

these

subjects

was

slightly

higher

for

the

negative

interactions

than

positive

However

results

from

the

younger

subjects

were

suggestive

of

traitbased

copying

The

change

of

P

had

our

hypothesis

been

agespecific

The

younger

and

older

females

differed

substantially

from

each

other

on

these

measures

for

attractiveness

ratings

P

Age

is

an

especially

relevant

factor

to

consider

in

the

context

of

copying

This

is

because

copying

is

potentially

useful

as

a

way

for

younger

individuals

to

learn

socially

from

more

experienced

individuals

who

themselves

have

the

benefit

of

hindsight

having

learned

through

a

combination

of

experience

and

social

learning

Pomiankowski

Some

decisions

improve

with

experience

and

so

with

age

In

such

cases

younger

individuals

are

expected

to

discriminately

copy

older

whereas

the

converse

is

not

necessarily

good

policy

and

potentially

misleading

Dugatkin

and

Godin

Ophir

and

Galef

Amlacher

and

Dugatkin

Vukomanovic

and

Rodd

Thus

agespecificity

is

predicted

of

social

copying

in

general

and

potentially

of

matechoice

copying

in

particular

The

prediction

that

age

or

experience

affect

matechoice

copying

has

been

investigated

in

other

species

Experience

appears

not

to

affect

matechoice

copying

in

Coturnix

quail

Ophir

and

Galef

Female

guppies

appear

to

discriminately

copy

older

females

Dugatkin

and

Godin

Amlacher

and

Dugatkin

Vukomanovic

and

Rodd

Though

previous

studies

of

matechoice

copying

in

humans

have

not

reported

agespecific

effects

Waynforth

found

an

analogous

association

with

experience

Less

sexually

experienced

females

showed

clearer

evidence

of

individualbased

copying

However

traitbased

copying

may

behave

differently

As

it

is

a

way

of

learning

about

kinds

of

mates

rather

than

the

quality

of

an

individual

mate

as

with

individualbased

copying

it

is

a

solution

to

a

different

sort

of

problem

Mate

seekers

of

any

age

may

benefit

from

social

information

about

particular

mates

but

perhaps

not

from

copying

general

preferences

from

their

younger

rivals

Thus

Experiment

was

conducted

to

test

the

hypothesis

that

human

females

on

the

cusp

of

adulthood

will

show

traitbased

copying

with

the

only

difference

from

Experiment

being

the

age

of

participants

Methods

Forty

female

participants

aged

years

mean

SD

were

recruited

as

in

the

above

experiments

The

upper

age

criterion

was

set

at

the

median

of

Experiment

sample

the

lower

age

criterion

was

enforced

by

our

restriction

to

use

of

adult

participants

The

design

and

stimuli

were

the

same

as

in

Experiment

Figure

Results

from

female

subjects

in

Experiment

Bars

show

average

SEM

change

in

rating

of

the

classes

of

stimuli

target

similartotarget

or

control

in

terms

of

appeal

as

a

potential

longterm

partner

separately

for

whether

the

subject

had

perceived

the

interaction

as

positive

light

bars

or

negative

dark

bars

Matechoice

copying

is

evidenced

where

the

change

in

ratings

is

higher

when

interest

is

perceivedhere

for

target

stimuli

and

for

similartotarget

faces

Figure

Results

from

female

subjects

in

Experiment

Bars

show

average

SEM

change

in

rating

of

the

classes

of

stimuli

target

similartotarget

or

control

in

terms

of

appeal

as

a

potential

longterm

partner

separately

for

whether

the

subject

had

perceived

the

interaction

as

positive

light

bars

or

negative

dark

bars

Matechoice

copying

is

evidenced

where

the

change

in

ratings

is

higher

when

interest

is

perceivedhere

for

target

stimuli

and

for

similartotarget

faces

Results

As

in

all

the

above

experiments

individualbased

copying

was

observed

whereas

control

faces

showed

no

differences

and

analogous

results

were

obtained

whether

perceived

or

actual

interest

was

used

to

define

positive

and

negative

cases

Table

Furthermore

ratings

of

similartotarget

faces

were

also

higher

after

viewing

target

males

in

positive

interactions

than

in

negative

for

longterm

interest

P

and

showing

a

suggestive

analogous

trend

for

attractiveness

ratings

P

evidencing

traitbased

copying

in

young

females

The

younger

subjects

here

differed

not

only

in

absolute

age

compared

with

previous

subjects

but

also

in

age

relative

to

the

models

observed

in

the

videos

Is

it

that

traitbased

copying

fades

with

copiers

age

or

that

it

is

specific

to

copying

models

older

than

oneself

As

the

speeddating

models

were

on

average

substantially

older

years

mean

SD

than

the

subject

samples

of

both

Experiment

years

and

Experiment

years

the

difference

in

traitbased

copying

between

the

samples

is

difficult

to

attribute

to

differences

in

the

relative

age

between

samples

and

models

Thus

the

The

agespecificity

observed

in

traitbased

copying

of

the

culturally

acquired

traits

for

females

was

not

seen

among

male

subjects

However

all

subject

samples

were

from

a

similarly

narrow

range

of

ages

years

Though

a

similar

range

of

ages

was

apparently

sufficient

to

show

age

differences

among

females

an

analogous

change

may

develop

in

males

at

a

later

age

Thus

males

may

also

have

shown

a

developmental

course

in

traitbased

copying

if

a

broader

range

of

ages

were

considered

These

facts

oblige

us

to

be

tentative

about

drawing

conclusions

regarding

the

ontogenetic

course

of

traitbased

copying

whether

the

agedependence

is

Though

these

results

do

not

directly

show

that

the

teen

females

differ

from

their

slightly

older

peers

they

do

show

traitbased

copying

among

the

younger

females

In

the

context

of

Experiment

in

which

the

same

age

range

showed

very

similar

results

whereas

our

older

subjects

showed

no

indication

of

traitbased

copying

at

all

we

tentatively

conclude

that

traitbased

copying

is

specific

to

the

youngest

adult

females

Further

research

specifically

on

the

age

course

of

this

effect

is

necessary

for

the

drawing

of

stronger

conclusions

DISCUSSION

Each

of

the

above

experiments

replicates

earlier

findings

Place

et

al

that

ones

assessment

of

anothers

appeal

is

heightened

upon

acquiring

social

information

indicating

that

person

as

a

successful

mate

This

is

individualbased

matechoice

copying

Seeing

someone

succeed

in

winning

some

sexual

interest

of

a

potential

mate

makes

that

person

more

attractive

to

observing

third

parties

But

when

we

acquire

such

information

have

we

learned

something

exclusively

about

the

observed

individual

or

something

more

general

applicable

also

to

other

potential

mates

with

shared

characteristics

The

present

results

suggest

that

this

kind

of

generalizationtraitbased

matechoice

copyingoccurs

in

humans

but

that

it

is

specific

to

culturally

malleable

cues

conspicuously

not

facial

traits

We

Though

clothing

body

decorations

and

ways

of

keeping

ones

hair

are

tangible

traits

important

to

human

mate

choice

such

traits

are

inherited

primarily

culturally

Meskó

and

Bereczkei

Wohlrab

et

al

though

not

wholly

eg

hair

styles

depend

in

part

on

the

natural

color

and

texture

of

the

hair

For

such

traits

the

evolution

of

nonsocial

recognition

mechanisms

is

unlikely

so

our

rationale

for

not

expecting

traitbased

copying

may

not

apply

with

respect

to

such

traits

Yet

the

informational

benefits

may

still

accrue

so

long

as

the

cultural

trappings

of

successful

mates

are

indicative

of

mate

quality

in

others

which

may

be

true

Thus

traitbased

copying

may

be

appropriate

with

respect

to

culturally

acquired

characteristics

while

not

to

immediately

observable

and

highly

heritable

traits

such

as

facial

characteristics

Shared

cultural

tastes

Experiment

was

the

last

of

a

series

of

experiments

not

reported

here

designed

to

get

at

the

same

question

all

with

the

same

basic

design

described

above

but

with

varying

levels

of

facial

similarity

of

the

similartotarget

faces

Our

first

attempt

relied

on

morphing

software

which

allows

the

creation

of

the

average

of

photographs

Thus

our

similarity

manipulation

in

that

case

was

to

create

and

show

the

midpoint

between

the

target

person

seen

in

the

video

interaction

and

some

other

face

and

this

functioned

as

our

similartotarget

face

for

each

target

Subjectively

this

succeeded

in

producing

a

face

Our

claim

is

specific

to

what

we

manipulated

We

note

that

facial

and

hairclothing

qualities

differ

in

the

manner

in

which

they

are

inherited

and

that

this

may

account

for

the

conspicuous

observed

dissociation

between

traitbased

copying

on

the

basis

of

these

kinds

of

traits

However

our

results

do

not

permit

us

to

draw

general

conclusions

regarding

other

culturally

or

genetically

inherited

traits

eg

nose

rings

or

skin

tones

facial

features

external

to

those

we

varied

such

as

the

jawline

implicated

as

a

matechoice

criterion

Cunningham

et

al

or

more

extreme

manipulations

of

specific

features

beyond

the

natural

variation

of

a

racially

and

culturally

homogeneous

population

with

which

we

are

concerned

here

To

determine

whether

or

how

such

traits

may

generalize

when

copying

would

oblige

further

experiments

Already

Little

et

al

have

shown

that

manipulations

mimicking

betweenpopulation

variation

can

produce

analogous

effects

They

created

sets

of

exaggerated

images

of

faces

of

artificial

morphs

inner

faces

with

very

widelyspaced

eyes

versus

very

narrowlyspaced

and

paired

each

set

with

images

of

attractive

or

unattractive

oppositesex

inner

faces

Subjects

showed

generalized

changes

in

preference

for

similarly

altered

novel

inner

faces

However

the

systematic

manipulation

exaggerated

stimuli

and

dichotomous

distribution

of

traits

are

methodological

contrivances

that

may

enhance

generalization

leaving

in

question

how

Little

et

al

results

pertain

to

natural

human

withinpopulation

mating

Though

it

is

perhaps

not

surprising

that

particular

manipulations

can

produce

generalization

this

makes

an

interesting

comparison

with

our

findings

Between

populations

particularly

between

races

facial

traits

might

fall

in

distinguishable

clusters

as

in

Little

et

al

whereas

withinpopulations

which

is

our

focus

variation

will

be

largely

continuous

These

very

different

distributions

of

facial

traits

may

strongly

impact

patterns

of

social

information

use

Testing

the

boundaries

of

traitbased

copying

in

theoretically

meaningful

ways

is

one

useful

direction

for

future

research

For

the

current

study

however

we

have

limited

ourselves

to

real

inner

and

outer

faces

from

an

actual

population

of

daters

to

assure

relevance

to

natural

human

mate

choice

We

conclude

that

traitbased

matechoice

copying

for

inner

facial

qualities

is

conspicuously

absent

given

the

naturally

occurring

variation

in

a

homogeneous

human

population

while

demonstrably

present

for

hair

It

remains

a

viable

possibility

that

our

results

can

be

understood

in

terms

of

attentional

biases

in

a

manner

that

converges

with

findings

from

face

recognition

research

Whereas

inner

facial

traits

are

more

heavily

relied

upon

for

the

recognition

of

familiar

faces

for

unfamiliar

faces

people

rely

equally

Ellis

et

al

or

preferentially

Haig

Bruce

et

al

on

head

shape

and

hair

Though

not

a

question

our

study

was

designed

to

address

our

results

are

consistent

with

the

possibility

that

traitbased

copying

relies

on

such

attentional

biases

and

the

dissociation

observed

between

generalizing

with

respect

to

inner

facial

cues

and

cues

external

to

this

region

may

be

meaningfully

linked

to

how

humans

attend

to

unfamiliar

faces

Agreement

of

attractiveness

ratings

shows

that

our

subjects

attended

to

innerfacial

characteristics

but

does

not

convey

the

relative

salience

of

these

to

other

cues

This

view

leads

to

the

prediction

that

manipulations

of

attention

will

influence

the

occurrence

of

traitbased

copying

Little

et

al

as

well

as

aspects

of

the

circumstance

or

observer

that

have

been

associated

specifically

with

differences

in

how

people

attend

to

faces

eg

familiarity

Ellis

et

al

or

image

resolution

Jarudi

and

Sinha

including

aspects

of

relevance

to

mate

choice

Perhaps

the

sex

and

age

differences

we

found

for

instance

can

be

understood

in

such

terms

It

is

not

obvious

that

the

same

cues

will

be

similarly

salient

in

face

recognition

and

mate

choice

In

reviewing

what

cues

people

find

salient

in

faces

Shepherd

et

al

concludes

that

different

parts

of

the

face

are

attended

to

according

to

the

task

p

It

will

be

important

to

ask

what

causes

different

cues

to

be

salient

in

different

situations

and

whether

and

why

the

cues

that

are

salient

for

individual

recognition

may

also

be

salient

for

mate

choice

Exploring

how

the

mechanisms

underlying

generalization

of

social

information

usage

may

interact

with

biases

involved

in

the

recognition

of

faces

is

an

interesting

avenue

for

future

research

In

all

previous

studies

assessing

traitbased

copying

empirically

each

with

a

different

species

such

copying

was

observed

but

in

of

these

studies

was

the

effect

seen

to

be

specific

to

certain

categories

of

cues

In

quail

traitbased

copying

occurred

with

both

naturally

occurring

cues

white

feathers

on

the

crown

and

arbitrary

cues

colored

dot

on

the

chest

White

and

Galef

In

zebra

finch

it

was

an

artificial

red

crest

adornment

Kniel

et

al

or

colored

leg

bands

Swaddle

et

al

which

were

reported

to

be

neutral

with

respect

to

mate

preferences

though

the

particular

colors

used

in

Swaddle

et

al

white

and

orange

are

the

very

colors

of

the

sexual

dimorphisms

in

zebra

finch

which

may

have

had

an

influence

on

the

results

obtained

Female

fruit

flies

generalized

to

painted

males

Mery

et

al

which

appears

to

be

a

wholly

arbitrarily

imposed

trait

Mollies

Witte

and

Noltemeier

and

guppies

Godin

et

al

showed

traitbased

copying

with

respect

to

size

and

extent

of

body

coloring

respectively

traits

that

are

important

matechoice

criteria

in

these

species

Individualbased

and

traitbased

matechoice

copying

appears

to

provide

solutions

to

separate

kinds

of

problem

The

benefit

of

the

individualbased

effect

appears

specific

to

the

individual

and

it

remains

good

usage

of

information

whatever

the

mate

seekers

age

or

experience

level

Though

it

can

be

argued

that

less

experienced

mate

seekers

get

an

extra

benefit

with

copying

Waynforth

we

find

individualbased

copying

independent

of

the

ages

we

tested

see

also

Place

for

the

same

result

across

a

wider

age

range

As

traitbased

copying

does

appear

to

depend

on

age

with

only

the

youngest

women

generalizing

copying

to

the

similarly

styled

and

shows

specificity

to

particular

kinds

of

cues

it

appears

to

be

a

separable

effect

with

a

separate

function

The

information

value

in

traitbased

copying

in

humans

appears

to

be

in

young

mate

seekers

learning

more

generally

about

the

culturally

acquired

qualities

of

successful

mates

from

the

choices

of

rivals

If

indiscriminate

social

learning

can

pull

the

learner

into

maladaptive

informational

cascades

Bikhchandani

et

al

in

which

the

modal

spreads

for

better

or

for

worse

As

misinformation

can

spread

socially

as

readily

as

veridical

information

social

learning

must

be

selective

to

be

useful

Laland

Traitbased

matechoice

copying

in

humans

shows

selectivity

of

cue

use

as

well

as

observer

specificity

copy

when

young

in

ways

that

make

functional

sense

The

limited

cases

in

which

generalization

is

found

across

our

studies

is

an

interesting

and

surprising

outcome

suggestive

of

selective

pressures

at

work

rather

than

a

broadly

applied

general

learning

General

versus

specific

mechanism

Is

matechoice

copying

in

humans

the

workings

of

a

general

or

specific

mechanism

If

copying

in

humans

abides

the

functional

prescription

to

limit

traitbased

copying

despite

the

phylogenetic

inertia

for

generalization

a

specific

ad

hoc

mechanism

is

suggested

This

prediction

appears

to

be

supported

by

our

results

Though

matechoice

copying

appears

in

both

sexes

the

patterns

with

which

it

generalizes

to

similar

others

varies

by

cue

and

age

in

ways

consistent

with

functional

considerations

These

results

put

pressure

on

claims

that

matechoice

copying

is

an

associative

process

involving

association

with

the

model

Witte

and

Godin

recently

concluded

that

considerable

empirical

evidence

supports

the

general

view

that

matechoice

copying

best

corresponds

to

an

associative

learning

mechanism

wherein

a

focal

observer

female

associates

a

cue

from

the

model

female

with

the

accepted

or

rejected

male

involved

p

Whether

this

is

the

general

view

is

debatable

There

is

compelling

evidence

against

a

general

association

account

of

matechoice

copying

among

some

species

For

instance

Coturnix

quail

show

striking

and

ecologically

understandable

sex

differences

in

the

ways

in

which

they

are

affected

by

matechoice

information

in

both

direction

Galef

and

White

White

and

Galef

and

duration

White

and

Galef

We

present

evidence

that

matechoice

copying

in

humans

specifically

behaves

unlike

the

proposed

model

cue

to

target

association

would

predict

failing

to

generalize

in

a

cuespecific

agespecific

manner

This

is

not

to

deny

that

associative

learning

processes

may

have

some

involvement

It

is

not

obvious

whether

the

lack

of

generalization

to

the

facial

characteristics

we

manipulated

indicates

an

adapted

repression

of

a

general

tendency

for

traitbased

copying

or

whether

the

generalization

of

learning

seen

toward

people

with

similar

hair

and

clothing

is

itself

a

specific

adaptation

However

the

absence

of

generalization

to

certain

cues

bolsters

the

view

that

the

learning

It

is

intriguing

that

culturally

transmitted

traits

and

not

facial

characteristics

turned

out

to

be

subject

to

traitbased

matechoice

copying

meaning

that

the

attraction

to

them

is

likewise

subject

to

cultural

inheritance

Brooks

The

form

of

learning

mirrored

the

thing

learned

about

Our

subjects

learned

generalizations

about

culturally

acquired

characteristics

and

individually

about

qualities

that

are

specific

to

individuals

Sexual

selection

The

question

of

traitbased

matechoice

copying

first

emerged

in

the

context

of

sexual

selection

Brooks

It

was

realized

early

that

matechoice

copying

would

impact

sexual

selection

Wade

and

PruettJones

Dugatkin

Gibson

and

Höglund

as

had

been

acknowledged

for

other

forms

of

social

learning

eg

sexual

imprinting

ten

Cate

and

Bateson

Matechoice

copying

leads

to

a

further

favoring

of

the

favored

which

will

influence

sexual

selection

However

there

are

many

factors

that

may

determine

the

form

of

this

influence

notably

whether

copying

is

traitbased

or

exclusively

individual

based

Traitbased

copying

favors

not

only

the

favored

but

also

the

traits

of

the

favored

It

creates

preference

for

the

traits

of

successful

individuals

and

so

will

focus

selection

on

those

traits

specifically

This

may

have

conflicting

effects

on

sexual

selection

As

it

concentrates

selection

specifically

on

traits

associated

with

reproductive

success

it

may

exacerbate

skews

in

reproductive

variance

associated

with

heritable

traits

As

a

consequence

directional

sexual

selection

will

receive

a

distinct

boost

Brooks

White

and

Galef

However

in

a

large

enough

mating

pool

because

copiers

will

more

often

witness

modal

phenotypes

succeeding

than

rarer

phenotypes

traitbased

copying

may

also

focus

selection

differentially

on

prevalent

characters

and

so

have

a

conservative

stabilizing

influence

on

sexual

selection

Kirkpatrick

and

Dugatkin

The

relative

weight

of

these

conflicting

selection

pressures

will

depend

potentially

very

strongly

on

the

sort

of

trait

generalized

The

former

directional

influence

assumes

that

the

traits

showing

such

generalization

are

heritable

for

example

facial

traits

the

latter

stabilizing

influence

will

operate

similarly

upon

either

sort

of

trait

What

can

we

now

say

about

how

we

expect

copying

to

be

impacting

human

evolution

To

understand

the

systematic

impact

that

individualbased

copying

may

have

on

sexual

selection

we

would

need

to

be

able

to

quantify

how

closely

matechoice

decisions

correlate

with

heritable

characteristics

However

for

traitbased

copying

the

connection

is

now

somewhat

clearer

If

as

our

results

suggest

for

humans

matechoice

copying

generalizes

particularly

readily

to

hair

and

clothing

styles

which

are

primarily

culturally

acquired

traits

then

the

influence

of

copying

on

sexual

selection

will

most

likely

be

stabilizing

favoring

selection

of

modal

characters

The

study

of

traitbased

copying

CONCLUSION

Matechoice

copying

in

humans

has

now

been

reproduced

in

several

laboratories

using

as

many

variants

of

method

Here

we

have

provided

evidence

not

only

for

individualbased

copying

but

for

traitbased

copying

as

well

showing

that

this

is

specific

to

certain

types

of

traits

and

that

the

use

of

traitbased

copying

changes

in

early

adulthood

This

behavior

has

apparent

functional

significance

and

understandable

impact

on

sexual

selection

Though

matechoice

copying

has

most

often

been

approached

as

a

specific

learning

mechanism

there

have

been

proposals

that

the

available

evidence

suggests

reliance

on

general

associative

learning

mechanisms

Our

finding

of

cuespecific

generalization

in

Huxley

development

Tinbergen

and

subjectivity

Burghardt

coalesce

in

a

fuller

understanding

of

the

animal

evolution

and

cognition

To

Kunderas

revelation

that

when

assessing

men

women

utilize

information

about

the

mate

choices

of

other

women

we

add

that

humans

of

both

sexes

appear

to

generalize

their

use

of

these

social

cues

to

inform

their

assessments

of

the

similarly

styled

but

conspicuously

show

no

hint

of

such

generalization

to

the

facially

similar

FUNDING

JBA

acknowledges

support

by

grant

As

of

the

German

Research

Foundation

DFG

LP

acknowledges

funding

from

the

Biotechnology

and

Biological

Sciences

Research

Council

Engineering

and

Physical

Sciences

Research

Council

Economic

and

Social

Research

Council

and

Medical

Research

Council

SSP

was

supported

by

a

National

Science

Foundation

IGERT

fellowship

from

the

Indiana

University

Cognitive

Science

Program

RIB

was

supported

by

a

supplemental

research

fellowship

from

the

Indiana

University

Cognitive

Science

Program

We

thank

Bennett

Galef

David

White

and

anonymous

reviewers

for

providing

helpful

comments

on

drafts

of

the

manuscript

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