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Dongho Kim, Savannah Lokey, Jianfei Guo, Franco Pestilli, Sam Ling; Human visual response gain increases with arousal. Journal of Vision 2015;15(12):567. https://doi.org/10.1167/15.12.567.
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How do states of arousal affect perception? Large gains have been made in characterizing how top-down processes, such as attention, influence vision. However, measurements of the effects of arousal on human perception are relatively limited and the underlying mechanisms remain surprisingly far less understood. Here, we examine the modulatory role of arousal on one of the cornerstones of vision: the contrast response function. To do so, we measured contrast psychometric functions in two groups of subjects. One group – high-arousal – was asked to refrain from eating and drinking for 5 hours prior to the experiment. The other group – low-arousal – was allowed normal access to eating and drinking and was given water prior to the experiment. During the experiment, both groups received drops of water at 80% probability coincident with stimulus presentation, throughout the experiment. Participants performed a fine orientation discrimination task on a grating shown at fixation, which varied in contrast from trial-to-trial. Water during the experiment aroused participants differently depending on deprivation history: when deprived, water drops led to high levels of arousal, when satiated, water drops led to lower levels of arousal. Results reveal that participants in the high-arousal group yielded psychometric functions that saturated (Rmax) significantly higher than the low-arousal group, consistent with an increase in the response gain of the underlying contrast response. However, we found no difference in the semi-saturation constant (C50) between the two groups. These findings are in line with reports from animal models showing a multiplicative effect of alertness on the contrast response function in LGN neurons (Cano et al., 2006). and suggests that arousal alters early visual perception by mitigating suppressive neural activity, thereby boosting neural responsivity and perceptual sensitivity.
Meeting abstract presented at VSS 2015
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