Limited featured-based attention to multiple features

Abstract

Attending to a feature (e.g., color or motion direction) can enhance the early visual processing of that feature. However, it is not known whether one can simultaneously enhance multiple features. We examined people's ability to attend to multiple features in a feature cueing paradigm. Each trial contained two intervals consisting of a random dot motion stimulus. One interval (noise) had 0% coherence (no net motion), while the other interval (signal) moved in a particular direction with varying levels of coherence. Participants reported which interval contained the signal in one of three cueing conditions. In the one-cue condition, a line segment preceded the stimuli indicating the direction of the signal with 100% validity. In the two-cue condition, two lines preceded the stimuli, indicating the signal would move in one of the two cued directions. In the no-cue condition, no line segment appeared before the dot stimuli. In several experiments, we consistently observed a lower detection threshold in the one-cue condition than the no-cue condition, showing that participants can enhance processing of a single feature. However, detection threshold was consistently higher for the two-cue than one-cue condition, indicating that participants could not simultaneously enhance two motion directions as effectively as one direction. This finding revealed a severe capacity limit in our ability to enhance early visual processing for multiple features.

Limits in feature-based attention to multiple colors

“…The reduced cueing effect in the two-cue condition demonstrates a limit in the ability to attend multiple colors, which is similar to our previous finding on attention to motion directions (Liu et al, 2013). We note that two colors are well within the storage capacity of working memory, which is estimated to be 3-4 items (Cowan, 2001; Luck & Vogel, 1997).…”

“…Third, we reduced decision uncertainty by not presenting the cued, non-target color (see Experiment 1 Discussion). The experimental design is similar to our previous work on attention to motion direction (Liu et al, 2013). The color coherence manipulation is also analogous to the motion coherence manipulation in the well-studied random dot motion task (Britten, Shadlen, Newsome, & Movshon, 1992; Britten et al, 1992).…”

“…Observers gave written informed consent under the study protocol approved by the Institutional Review Board at Michigan State University and were remunerated at a rate of $10/hour (except the author). We based our sample size on our previous study on feature-based attention to motion (Experiment 1 of Liu et al, 2013), which used a similar experimental design and analytical approach. The effect size for comparison between one-cue and no-cue condition in that experiment was 1.88.…”

“…However, these studies do not provide a precise estimate of the limit of feature-based attention, nor were they designed to achieve such an objective. A recent study by us addressed this question by manipulating the number of discrete directional cues in a motion detection task (Liu, Becker, & Jigo, 2013). Compared to a baseline neutral condition, performance was improved when observers attended to a single direction, as well as when they attended to two orthogonal directions.…”

Attentional modulation: Target selection, active search and cognitive processing

“…They found that in orientation discrimination, feature attention always increased response gain, regardless of whether the uncertainty of the attended feature was low or high. Liu, Becker, and Jigo (2013) also addressed the issue of feature uncertainty and showed that the decrement in performance when observers attend to multiple, discrete feature values, is similar to the uncertainty effects found in spatial attention, when the target can occur in one of multiple discrete, locations.…”