Abstract
Enumeration of canonical patterns (e.g., dot arrangements on dice) is more rapid and accurate than enumeration of randomized arrangements of visual items (Mandler and Shebo, 1982). While previous studies have shown that enumeration of randomized arrangements can be disrupted by attentional load (Olivers & Watson, 2008), the enumeration of canonical patterns under similar conditions has been unexplored. To investigate enumeration of canonical patterns under attentional load, we adapted a spatial dual-task paradigm in which subjects had two potential tasks: report the relative dimensions of a centrally-located cross and enumerate a peripheral cluster of dots appearing in a random quadrant. Subjects were asked to either perform the peripheral task only (full attention trials) or both tasks (divided attention trials). Crowd-sourced participants (n=88) were split between randomized and dice pattern arrangement conditions. A repeated measures ANOVA showed significant within-subjects effects of attentional load, F(1,86)=106.56, p< .001, and cluster numerosity, F(4.03,346.96)=157.96, p< .001. Interaction effects were found between numerosity and arrangement, F(4.03,346.96)=13.14, p< .001, and numerosity and attentional load, F(4.45,382.52)=5.23, p< .001. We replicated previous findings for randomized arrangements, with enumeration error increasing with cluster numerosity and attentional load. For dice patterns, enumeration error also increased under attentional load. Additionally, contrary to findings from studies on single-task enumeration of dice patterns, we observed conflation of patterns with similar outlines. Specifically, in both full and divided attention trials, participants conflated dice patterns of six and five with four and patterns of three with two. In subsequent experiments, we swapped the peripheral and central tasks, placing the dot cluster in the center. With centrally-located canonical patterns, enumeration accuracy was consistent with results from single-task studies. We hypothesize that subjects may be using shape cues to inform guessing during enumeration tasks when unable to both localize and fully attend to target patterns.
Acknowledgement: This work was supported by a NRC Research Associateship award to GB, and AFOSR MIPR grant #F4FGA07074G001 and ONR grant #N0001416WX00762, both awarded to PB.