Is feature-based attention always spatially global during visual search?

Editor's Note: These short, critical reviews of recent papers in the Journal, written exclusively by graduate students or postdoctoral fellows, are intended to summarize the important findings of the paper and provide additional insight and commentary. For more information on the format and purpose of the Journal Club, please see The visual system has a limited capacity, so visual inputs must compete for representation in visual cortex. Attentional mechanisms resolve this competition by selecting a subset of behaviorally relevant information for processing on the basis of location or nonspatial features, such as color (for review, see Carrasco, 2011). One mechanism for attentional selection is modulation of neural gain such that the neuronal response to attended stimuli is amplified relative to unattended inputs (Hillyard et al., 1998). Numerous studies suggest that feature-based attention operates globally, such that neural gain for an attended feature (e.g., the color red or upward motion) is amplified across the entire visual field. For example, Treue and Martínez Trujillo (1999) demonstrated that attending to a feature (direction of motion) in one visual hemifield modulated the response of visual neurons with receptive fields in the opposite hemifield. Additional evidence for global feature-based attention has subsequently come from studies using a range of methodolo-gies, including single-unit recordings in monkeys Although there is strong evidence that global feature-based attention occurs in most experimental settings, it is less clear whether spatial attention can narrow the scope of feature-based attention. If relevant stimuli only appear in one portion of the visual field (e.g., near fixation), it may be advantageous to restrict feature-based attention to the relevant location. A recent study in The Journal of Neuro-science by Painter et al. (2014) examined whether task demands influence the scope of feature-based attention. Most studies of feature-based attention have used tasks in which participants monitor a single stimulus for a subtle change in a target feature (e.g., a decrement in luminance). Instead of such a simple attentional monitoring task, Painter and colleagues (2014) used a visual search task to examine the effects of feature-based attention. In this task, participants searched sequential arrays of items presented at fixation for targets with a defined feature (a specific color), while task-irrelevant stimuli flickered in the periphery. Given the privileged status of central vision in directing attention within displays (Hollingworth et al., 2001), a fixated central display with task-irrelevant peripheral stimuli may be a prime situation in which feature-based …