An experimental group is the group in an experiment that receives the variable being tested. One variable is tested at a time. The experimental group is compared to a control group, which does not receive the test variable. In this way, experimental groups are used to find answers in an experiment.
1 At around 9 months of age, babies begin to pull themselves up to a standing position. 2  By 10 months of age, a baby should be able to grasp objects with thumb and forefinger.
Synolds and Pronko (1949), for instance, asked 74 children between 3 and 8 years of age to name eight colors from the Dvorine Color Perception Testing Charts, and their data exemplify the startling increase in naming accuracy that occurs around 5 years of age (Table 1).