Attention has played a central role in perception research since the dawn of experimental psychology. Over the past 20 years, the neurophysiological basis of visual attention has become an active area of research, and the field of visual psychophysics has developed rigorous methods for measuring and characterizing the effects of attention on visual performance, yielding an explosion of findings. These experiments have documented a bewildering variety of empirical phenomena, some of which appear to be mutually contradictory. One example concerns the interaction between attention and visual stimulus contrast. The results of some experiments suggest that attention increases neuronal responses multiplicatively by applying a fixed response gain factor. Other results suggest a change in contrast gain. Still other results suggest that attention may have a fixed additive effect, which can be approximated as a combination of both response gain and contrast gain changes. These ostensibly contradictory empirical findings have been paralleled by theoretical ideas that have been taken to represent alternative models of attention. We propose to develop and test a computational theory, called the normalization model of attention, and to unify/reconcile various alternative, and seemingly conflicting, empirical findings and theoretical models of the effects of attention on neuronal activity in visual cortex.
We aim : (1) to show that the proposed model can exhibit response gain changes, contrast gain changes, and additive-like combinations of response and contrast gain changes, depending on the stimulus conditions and the spread of the attention field;(2) to test the hypothesis that the effect of attention on behavioral performance and perceptual appearance systematically shifts from a change in response gain to contrast gain by manipulating the stimulus size and the spatial extent of the attention field;and (3) to test the hypothesis that attention modulates activity in visual cortex as predicted by the model, and to link attentional modulation of cortical activity (as measured with functional magnetic resonance imaging) with attentional modulation of behavioral performance (as measured psychophysically). The proposed research will utilize convergent information gained from various techniques (computational theory, previous electrophysiology experiments, and novel psychophysics and functional imaging experiments) to contribute to our understanding of how the brain processes visual information, how neural activity is related to visual attention and perception, and how visual processing interacts with other brain systems underlying cognition, in particular, attention.
The experimental protocols and theoretical principles that we develop for studying vision and attention in healthy human subjects will be readily applicable to patient populations. A better understanding of visual attention will lead to a better understanding of factors limiting peripheral vision, which are critical when central vision is compromised due to macular degeneration and related visual deficits. Basic knowledge of visual attention has implications for our understanding of several neuropsychological disorders, including unilateral neglect, schizophrenia and ADHD, and for informing the development of diagnostic tests of these disorders.
|Wang, Helena X; Yuval-Greenberg, Shlomit; Heeger, David J (2016) Suppressive interactions underlying visually evoked fixational saccades. Vision Res 118:70-82|
|Westrick, Zachary M; Heeger, David J; Landy, Michael S (2016) Pattern Adaptation and Normalization Reweighting. J Neurosci 36:9805-16|
|Li, Hsin-Hung; Barbot, Antoine; Carrasco, Marisa (2016) Saccade Preparation Reshapes Sensory Tuning. Curr Biol 26:1564-70|
|Grubb, Michael A; White, Alex L; Heeger, David J et al. (2015) Interactions between voluntary and involuntary attention modulate the quality and temporal dynamics of visual processing. Psychon Bull Rev 22:437-44|
|Li, Hsin-Hung; Carrasco, Marisa; Heeger, David J (2015) Deconstructing Interocular Suppression: Attention and Divisive Normalization. PLoS Comput Biol 11:e1004510|
|White, Alex L; Rolfs, Martin; Carrasco, Marisa (2015) Stimulus competition mediates the joint effects of spatial and feature-based attention. J Vis 15:7|
|Yuval-Greenberg, Shlomit; Merriam, Elisha P; Heeger, David J (2014) Spontaneous microsaccades reflect shifts in covert attention. J Neurosci 34:13693-700|
|Cutrone, Elizabeth K; Heeger, David J; Carrasco, Marisa (2014) Attention enhances contrast appearance via increased input baseline of neural responses. J Vis 14:16|
|Carrasco, Marisa; Barbot, Antoine (2014) How Attention Affects Spatial Resolution. Cold Spring Harb Symp Quant Biol 79:149-60|
|Grubb, Michael A; Behrmann, Marlene; Egan, Ryan et al. (2013) Exogenous spatial attention: evidence for intact functioning in adults with autism spectrum disorder. J Vis 13:|
Showing the most recent 10 out of 21 publications