Arousal-based pupil modulation is dictated by luminance.

Pupillometry has become a standard measure for assessing arousal state. However, environmental factors such as luminance, a primary dictator of pupillary responses, often vary across studies. To what degree does luminance interact with arousal-driven pupillary changes? Here, we parametrically assessed luminance-driven pupillary responses across a wide-range of luminances, while concurrently manipulating cognitive arousal using auditory math problems of varying difficulty. At the group-level, our results revealed that the modulatory effect of cognitive arousal on pupil size interacts multiplicatively with luminance, with the largest effects occurring at low and mid-luminances. However, at the level of individuals, there were qualitatively distinct individual differences in the modulatory effect of cognitive arousal on luminance-driven pupillary responses. Our findings suggest that pupillometry as a measure for assessing arousal requires more careful consideration: there are ranges of luminance levels that are more ideal in observing pupillary differences between arousal conditions than others.

Different computations underlie overt presaccadic and covert spatial attention.

Perception and action are tightly coupled: visual responses at the saccade target are enhanced right before saccade onset. This phenomenon, presaccadic attention, is a form of overt attention-deployment of visual attention with concurrent eye movements. Presaccadic attention is well-documented, but its underlying computational process remains unknown. This is in stark contrast to covert attention-deployment of visual attention without concurrent eye movements-for which the computational processes are well characterized by a normalization model. Here, a series of psychophysical experiments reveal that presaccadic attention modulates visual performance only via response gain changes. A response gain change was observed even when attention field size increased, violating the predictions of a normalization model of attention. Our empirical results and model comparisons reveal that the perceptual modulations by overt presaccadic and covert spatial attention are mediated through different computations.

Presaccadic attention improves or impairs performance by enhancing sensitivity to higher spatial frequencies.

Right before we move our eyes, visual performance and neural responses for the saccade target are enhanced. This effect, presaccadic attention, is considered to prioritize the saccade target and to enhance behavioral performance for the saccade target. Recent evidence has shown that presaccadic attention modulates the processing of feature information. Hitherto, it remains unknown whether presaccadic modulations on feature information are flexible, to improve performance for the task at hand, or automatic, so that they alter the featural representation similarly regardless of the task. Using a masking procedure, here we report that presaccadic attention can either improve or impair performance depending on the spatial frequency content of the visual input. These counterintuitive modulations were significant at a time window right before saccade onset. Furthermore, merely deploying covert attention within the same temporal interval without preparing a saccade did not affect performance. This study reveals that presaccadic attention not only prioritizes the saccade target, but also automatically modifies its featural representation.