UC Santa Barbara

Attention is a cognitive mechanism used to select important information. Here, importance is defined as one of three factors: image salience, or something that stands out based on local feature contrast; goal relevance, or items that are related to accomplishing a task; and selection history, or implicitly learned stimulus properties. Features of an item, like color and motion, are prioritized for attentional selection, but the exact mechanisms that allow for feature-specific attentional selection are unclear. Across three studies, evidence is presented on how information is attended based on feature-specific image salience, goal relevance, and selection history. Chapters 2 and 3 describe two fMRI studies investigating how feature-selective regions of visual cortex are recruited to track the location of color and motion stimuli throughout the visual field. Stimuli were either made salient because they were a different feature value from the rest of the display (Chapter 2), or relevant because participants were instructed to attend a certain feature dimension (Chapter 3). Inverted encoding models were computed to reconstruct spatial maps using neural activation patterns from retinotopic color (hV4/VO1/VO2) and motion (TO1/TO2) regions. Neural responses to the stimuli were strongest when the preferred feature of each region was important through manipulations of salience or relevance. These findings implicate color and motion areas as ‘feature dimension maps’—regions that are critical for indexing important color and motion information for attention. Chapter 4 describes a study concretely demonstrating that feature values learned over the course of an experiment can modulate what is prioritized. Specifically, the color of a regularly presented distracting stimulus was learned, and eventually ignored to improve target detection. Suppression was potent enough to interfere with ongoing goals, as participants took longer to select the target when it was shown in the learned distractor color. This rules out alternative accounts suggesting that only spatial information can be suppressed through selection history. Together, this body of work highlights how stimulus features are leveraged to successfully navigate our environment.