The Role of Preview and Incremental Delivery on Visual Search

The Role of Preview and Incremental Delivery on Visual Search Eric M. Chiu (echiu@ucmerced.edu) Michael J. Spivey (spivey@ucmerced.edu) Cognitive and Information Sciences, 5200 North Lake Road, Merced, CA 95343 USA Abstract fundamentals but rather a product of a single process better described as a graded enhancement of feature salience and supported by observations of improvement in visual search tasks (Olds, Cowan, & Jolicoeur, 2000a, 2000b, 2000c). Olds and colleagues (2000a, 2000b, 2000c) observed, in a series of experiments, some facilitatory effects as a result of the very brief duration when search displays had only single-feature distractors. Although observers’ responses were not as fast as with pure “pop-out” displays, Olds and colleagues (2000a, 2000b, 2000c) illustrated a graded improvement of search efficiency, by presenting single- feature visual search pop-out displays for very brief durations (in some conditions less than 100 milliseconds) before transitioning them to conjunction-search displays. Findings like this “search assistance,” along with signal detection theory analyses of visual search data (Eckstein, 1998), and a lack of a bimodal search efficiency distribution (Wolfe, 1998), has replaced the serial-parallel dichotomy account with a continuum of search efficiency (e.g., Nakayama & Joseph, 1998). Work by Spivey, Tyler, Eberhard, and Tanenhaus (2001) illustrates a different kind of “search assistance” phenomenon. Observers in an Audio/Visual Concurrent (A/V-concurrent) condition, where the conjunction-search display is presented concurrently with target identity via auditory linguistic queries (e.g. “Is there a red vertical?”), showed dramatically improved search efficiency compared to an Auditory-First control condition, where the same spoken query of target identity was provided prior to visual display onset. The findings suggest that upon hearing the first-mentioned adjective in the spoken query, visual attention is able to begin the search with only that feature, thus initiating the process more efficiency, resembling a single-feature search. Upon hearing the second adjective, several hundred milliseconds later, observers can then quickly find the target among the now attended subset of objects. Additionally, Reali, Spivey, Tyler, and Terranova (2006) implemented quantitative localist attractor simulations to extend the generalizability of the improvement in visual search efficiency when the identity of the conjunction target is delivered incrementally via a spoken target query while the stimulus display is visible, rather than prior to stimulus onset. Subsequently, Gibson, Eberhard, and Bryant (2005) found with faster speech (4.8 syllables/second vs. 3.0 syllables/second) the A/V-concurrent condition no longer provides an enhanced efficiency effect on conjunction- Recent studies show that visual search often involves a combination of both parallel and serial search strategies. Consequently, computational models and theoretical accounts of visual search processing have evolved from traditional parallel or serial descriptions to a continuum from “efficient” to “inefficient.” In our first experiments (1a & 1b), we demonstrate with various conditions that search efficiency does not increase with simultaneous delivery of target features in a conjunction-search task. In the second experiment, we explore effects of incremental non-linguistic information delivery and discover improvement of search efficiency. We find a facilitatory effect when non-linguistic visual delivery of target features is concurrent with the visual display onset, but not when the target features are delivered prior to display onset. The results support an interactive account of visual perception that explains linguistic and non- linguistic mediation of visual search as chiefly due to the incrementality of target feature delivery once search has begun. Keywords: visual search, incremental, conjunction, efficient Introduction The present study is part of a research program that explores the degree to which the incremental processing of spoken words in a full sentence can interact with concurrent visual search processes. Traditionally, two contrasting perspectives have plagued the field of attention in visual search. The serial-processing perspective claims that observers allocate complete attentional resources discretely and wholly to individual objects, one at a time (Treisman & Gelade, 1980; Treisman, 1988). Conversely, biased competition has been found to be mediated by neural mechanisms in the extrastriate visual cortex, which forms a persuasive line of reasoning not in favor of the serial-processing perspective but for the parallel-processing perspective, which claims attention is better characterized as a function of partially active representations of objects simultaneously contending for probabilistic mappings onto motor output (Desimone & Duncan, 1995, Reynolds & Desimone, 2001; Desimone, 1998). Single-feature visual search has been demonstrated to be relatively unaffected by the number of distractors, often inducing a perceptual “pop-out” effect. In contrast, two-feature conjunction-searches typically produce a linear increase in reaction time (RT) as the number of distractors increase. However, as we will demonstrate these apparent dichotomous perspectives may not be from two contrasting