No evidence that attentionally demanding dual tasks disrupt visual processing capacity in a gamified orientation-averaging task

How do task demands influence visual processing capacity? Previous studies (e.g. Dakin et al., 2009) conclude that attentionally demanding dual-tasks reduce functional sampling efficiency when performing concurrent visual ensemble processing tasks with a fixed number of visual elements. The current study examined this general claim more directly using an orientation averaging paradigm by systematically varying the number of visual elements to (1-16 Gabors). Orientation averaging accuracy and reaction time were obtained using a gamified first-person shooter task in a virtual reality environment (enemy on left vs right as informed by average Gabor orientation ± 5 degrees from vertical). We implemented cognitive load using an auditory n-back letter task (n = 1, 2, or 3) which was either self-paced (Experiment 1), proceeded automatically (Experiment 2), or performed via an ongoing auditory mathematical verbal shadowing task (Experiment 3). Our results showed that orientation averaging performance (accuracy and reaction time) deteriorated monotonically with increasing set size in all experiments and conditions. Whilst the more difficult cognitive load tasks induced significantly poorer orientation averaging performance in general, no variation was observed in the rate of performance decline with set size. In conclusion, in our study we found no evidence that attentionally demanding dual-tasks disrupt visual processing capacity, but overall accuracy is reduced.