Sana Shakir, “The Resolution of Visuospatial Attention is Variable Between Individuals”
Mentor: Adam Greenberg, Psychology
Attention is the process by which relevant sensory information is highlighted for further processing. Spatially selective attention in the visual domain has a limited resolution (i.e., the minimum spacing required between target items for attention to select one item, rather than both). Our goal was to measure this resolution through a novel paradigm in which a series of small, colored disks were arranged in a circle (at 10 degrees eccentricity) around a central stream of rapidly updating alphanumeric characters (which acted as a fixation point). The central stream consisted primarily of letters with rare digits embedded during each trial. Participants were asked to respond by pressing the keyboard space bar as quickly as possible when they identified a digit in the central stream. Additionally, each trial contained a briefly presented (50 msec) cue: a single smaller black dot appearing on (or near) one of the colored peripheral disks. The entire display then disappeared while the participant selected (with a mouse) the color of the disk they believed was nearest to the black cue. We found that participants detected a digit within the central stream at a rate of 62%, suggesting that they maintained fixation throughout most trials. Subjects accurately identified the cued color on 28% of trials, which is well above chance performance. Analysis of color errors provides an estimate of the attentional resolution, in which we found a high degree of variability between individuals. Importantly, errors due to color space (e.g. selecting light blue instead of dark blue) can be differentiated from errors of spatial attention, and estimates of attentional window size change significantly when controlling for this confound. Our measurements of visuospatial resolution suggest that attention operates at a somewhat large granularity (compared to visual perception) and is highly variable between individuals.