Repetition streaks increase perceptual sensitivity in visual search of brief displays

Abstract

Studies examining possible priming effects on visual search have generally shown that repeating the same type of search facilitates or speeds performance. But such studies typically assess any priming via measuring response latency, in tasks where accuracy is at or near ceiling. This leaves open the possibility that criterion shifts alone might produce the apparent improvements, and such shifts could plausibly arise when, say, a particular type of repeated search display becomes predictable. Here we assessed criterion-free perceptual sensitivity (d′) for visual search, in two experiments that used brief masked displays to bring performance off ceiling. In Experiment 1, sensitivity for a relatively difficult search task improved with successive repetitions of the same type of search, with sensitivity enhanced for both target-present and target-absent trials. In Experiment 2, sensitivity for a search task requiring discrimination on a colour-singleton target likewise showed enhancement with repetition. Experiment 2 also showed that the priming effects seem to influence the speed of attention shifts towards the target rather than influencing visual acuity directly. We conclude that priming in visual search, arising due to repetition streaks, is characterized by genuine improvements in perceptual sensitivity, not just criterion shifts.

Acknowledgements

HMS was supported by The Icelandic Student Innovation Fund, AK was supported by research grants from the Human Frontiers Science Program and the University of Iceland, and JD was supported by the BBSRC (UK) and the Wellcome Trust.

Notes

¹Mauchly's test of sphericity was significantly different from zero so the degrees of freedom were adjusted using a Greenhouse-Geisser correction.

²Note that even though c would increase to the same degree as d′, the latter is a criterion free measure of sensitivity; increased d′ therefore indicates increased sensitivity, regardless of any changes in c.

³The formula d′=(√2)(z[ρ]), where ρ is the proportion correct, yielded similar results (see Wickens, 2002).