Abstract
Recent evidence indicates that emotion enhances contrast thresholds (Phelp, Ling & Carrasco, 2006), and perceptual sensitivity for low-spatial-frequency stimuli (Bocanegra & Zeelenberg, 2009). However, these studies report just the responses to various frequencies at a given contrast or vice versa rather than the contrast sensitivity function (CSF) – the appropriate measure to investigate the interaction between the spatial frequency and contrast. We therefore measured the CSF to provide a more complete description of the early vision as a function of emotional arousal. To acquire the observer’s CSF, we adopted the quick-CSF method (qCSF; Lesmes, Lu, Baek & Albright, 2010), a Bayesian adaptive inference with a trial-to-trial information gain strategy. We used a fear-conditioned stimulus (CS) to manipulate observer’s arousal level. During the conditioning phase, high or low pitch tones were designated as the CS+, and electrical shock served as the US; a 700-ms CS+ tone was followed by a 200-ms US. After conditioning, observers performed a 2-alternative forced-choice orientation discrimination task in which they judged on each trial whether or not a Gabor patch was tilted counterclockwise or clockwise. Each trial began with a CS tone for 700 ms, followed by a 1000-ms blank, and then a 50-ms Gabor grating (spatial frequencies were from 0.25 to 36 cpd; contrasts were from 0.1 to 100%). To measure the conditioning effect, we measured the skin-conductance response (SCR) across the study. In the arousing condition, participants had a broader spatial frequency range within which they could detect the tilt, reflecting greater CSF bandwidth than in the non-arousing condition (p <.001). In addition, the peak CSF sensitivity was shifted to lower spatial frequencies in the arousing condition compared with the non-arousing condition (p <.005). Thus, emotional arousal increased overall CSF sensitivity, particularly at lower spatial frequencies.
Meeting abstract presented at VSS 2012