Preattentive guidance of eye movements during triple conjunction search tasks: The effects of feature discriminability and saccadic amplitude

Abstract

Eye movements were monitored during the performance of triple conjunction search tasks. Stimuli varied in color, shape, and orientation. Across trials, the target was either present or absent, and displays consisted of 6, 12, or 24 stimuli. Stimulus discriminability was manipulated for the shape dimension, with half of the participants seeing displays of Es and Fs (low-discriminability [LD] condition) and half seeing displays of Cs and Ts (high-discriminability [HD] condition). Participants in both conditions performed two search tasks. In the single-feature (SF) task, the target stimulus shared one feature with each of the distractors, whereas in the two-feature (TF) task, it shared two features with each distractor. An examination of saccadic endpoints revealed that participants were more likely to fixate on distractor stimuli sharing color (SF task) or color and shape (TF task) with the target. This was a robust finding, being observed across participants, saccades of different amplitudes and sequential position, and following short and long latencies to move. The extent to which participants made use of shape information increased with discriminability.

Guidance of eye movements during conjunctive visual search: The distractor-ratio effect.

“…This indicates that, across all displays, participants searched through the subset of distractors which shared color with the target item. The finding of a difference in search performance and saccadic bias between the high-and low-discriminability conditions is consistent with D. E. Williams and Reingold (2001), showing that guided search flexibly accommodates to changes in the informativeness of stimulus dimensions.…”

“…Consistent with the guided-search model, stimulus dimensions such as color, shape, contrast polarity, and size have been shown to bias the distribution of saccadic endpoints in conjunctive search tasks (e.g., Findlay, 1997;Findlay & Gilchrist, 1998;Hooge & Erkelens, 1999;Luria & Strauss, 1975;Motter & Belky, 1998b;Pomplun, Reingold, Shen, 2001;Scialfa & Joffe, 1998;Shen, Reingold, Pomplun, D. E. Williams, in press; D. E. Williams & Reingold, 2001; L. G. Williams, 1966; but see Zelinsky, 1996).…”

“…However, when the orientation discrimination to distinguish the search target from the distractors was made more difficult (9º vs. vertical), Distractor-ratio Effect 9 stationary targets were easier to detect than were moving targets. Similarly, D. E. Williams and Reingold (2001) found that in color × shape × orientation triple conjunction search tasks, changing the discriminability along the shape dimension (high-discriminability: C vs. T; lowdiscriminability: E vs. F) induced different patterns of eye movements. Greater saccadic selectivity towards those distractors sharing shape with the target was observed when more discriminable shapes were employed.…”

Attention and eye-movement control in reading: The selective reading paradigm.

“…To 21 put this issue in perspective, it is instructive to consider similar findings concerning saccadic 22 selectivity in visual search (see Reingold & Glaholt, 2014, for a recent summary). Specifically, 23 perfect saccadic selectivity based on color cues was similarly not obtained in visual search 1 studies (see Williams & Reingold, 2001) despite the fact that such studies employed minimum 2 distances between adjacent display items that were much larger than the space between 3 distractors and targets in the present paradigm. In general terms, it is likely that some of the 4 fixations on distractors in the present study arose due to oculomotor noise.…”

A new look at novelty effects: Guiding search away from old distractors

“…Conversely, search becomes less efficient as target-distractor similarity increases, presumably because these target-like distractors are competing more strongly with the actual target for attention (e.g., Duncan & Humphreys, 1989;Wolfe, 1994). More direct support for this relationship has come from studies of eye movements during search, which have shown that the likelihood of a distractor being fixated increases with the number of features that it shares with a target (D. E. Williams & Reingold, 2001;Zelinsky, 2008;Zelinsky & Sheinberg, 1997; see also L. G. Williams, 1966, for an early observation). In addition to generally supporting the role of target-related guidance in search, such analyses of distractor fixations also enable one to identify the target features that are most important for guidance (e.g., Motter & Belky, 1998;Pomplun, 2006;Rutishauser & Koch, 2007; see also Tatler, Baddeley, & Gilchrist, 2005).…”