Abstract
How does attending to a moment in time augment vision? In this study, we examined the mechanisms by which temporal attention – the allocation of attention to a specific moment in time – enhances visual sensitivity. To do so, we employed an equivalent noise framework. Under this framework, one's visual sensitivity can be enhanced primarily in two ways: signal amplification and noise reduction. Benefits of signal amplification arise only when there is very little external noise in a visual scene, whereas benefits of noise reduction arise only when there is ample noise to reduce in a visual scene. To examine whether temporal attention improves perceptual performance by means of signal amplification, noise reduction, or a combination of both mechanisms, we assessed perceptual sensitivity for discriminating a target stimulus embedded in various levels of external noise. Specifically, observers performed a fine-orientation discrimination task, reporting the clockwise or counter-clockwise orientation of a sinusoidal grating that appeared at a random time-point within a window of a trial. Temporal attention was evoked by the random onset of an auditory pre-cue within a trial (focused attention condition), and compared to a condition in which no information was given regarding stimulus onset (distributed attention condition). Target stimuli were embedded in Gaussian noise of ten contrast levels (0-60% contrast). To evaluate the noise regime in which attention had its greatest effects, contrast thresholds were determined for each external noise level and attention condition. Results revealed large benefits of temporal attention across all external noise levels, implicating a combination of signal amplification and noise reduction mechanisms sub-serving the benefits of temporal attention.
Meeting abstract presented at VSS 2018