In each PPI test session throughout all 4 visits, male participants will begin with a resting baseline period of 5 minutes, where they will be asked to sit quietly and still in a sound and temperature controlled lab room, with their eyes open looking at a fixation cross on the monitor. Baseline is conducted to obtain measures of emotional arousal and sedation prior to the experimental manipulations. As such, during baseline psychophysiological measures will be collected. Self-reported emotional arousal will be obtained at the beginning and end of the baseline period using the Self-Assessment Manikin (Bradley, 1999), which assesses arousal and valence of affective state using Likert (1-9) scales. Self-reported level of sedation will be assessed at the same time points as emotional arousal (using a modified Self-Assessment Manikin using the same Likert 1-9 scale). Next, participants will be exposed to an initial adaptation phase, in order for them to become acquainted with the startle stimuli (pulses and prepulses), and their startle responses reach a stable level. In this phase, 4 blocks of prepulse-pulse (pP) and pulse-alone (P) trials will be presented, with an inter-trial interval (ITI) of 20 seconds (+/- 5 sec). After the initial adaptation phase, participants will be instructed to view a computer monitor where random geometric figures will be presented, while simultaneously 10 blocks of auditory pP and P trials will be presented with an ITI of 20 sec. Each test session will last around 15 minutes. At the end of the test session, the standardized lab test to assess the participants' attention level described above will be presented again.