Quantifying peripheral and foveal perceived differences in natural image patches to predict visual search performance

Abstract

Duncan and Humphreys (1989) identified two key factors that affected performance in a visual search task for a target among distractors. The first was the similarity of the target to distractors (TD), and the second was the similarity of distractors to each other (DD). Here we investigate if it is the perceived similarity in foveal or peripheral vision that determines performance. We studied search using stimuli made from patches cut from colored images of natural objects; differences between targets and their modified distractors were estimated using a ratings task peripherally and foveally. We used search conditions in which the targets and distractors were easy to distinguish both foveally and peripherally ("high" stimuli), in which they were difficult to distinguish both foveally and peripherally ("low"), and in which they were easy to distinguish foveally but difficult to distinguish peripherally ("metamers"). In the critical metameric condition, search slopes (change of search time with number of distractors) were similar to the "low" condition, indicating a key role for peripheral information in visual search as both conditions have low perceived similarity peripherally. Furthermore, in all conditions, search slope was well described quantitatively from peripheral TD and DD but not foveal. However, some features of search, such as error rates, do indicate roles for foveal vision too.

How ubiquitous is the direct-gaze advantage? Evidence for an averted-gaze advantage in a gaze-discrimination task

“…Recently, it has also been shown that the effect of attention capture by direct gaze and dynamic motion on social attention is restricted to conditions where participants were instructed to maintain fixation at the center of the screen (Boyer & Wang, 2018). Moreover, the role of foveal versus peripheral vision has been explicitly addressed with respect to their respective contribution to visual search (Hughes, Southwell, Gilchrist, & Tolhurst, 2016), indicating the importance of peripheral information in visual search tasks. In total, these examples from various areas of research suggest that central versus peripheral presentation of the gaze target might be an important factor to consider.…”

Target specificity improves search, but how universal is the benefit?

“…This suggests that foveal processing behaves similarly when specificity increases in both the orientation and spatial frequency feature dimensions. The smaller magnitude pictorial advantage in the spatial frequency condition may be the result of decreased peripheral preprocessing of targets and distractors (Alvarez & Oliva, 2009;Henderson et al, 1989;Henderson, 1992;Henderson and Hollingworth, 2003;Hughes et al, 2016).…”

“…At face value, the argument seems reasonable, visual acuity is known to drop from foveal to peripheral vision, resulting in a non-uniform perception of spatial frequency (Bennett & Banks, 1991). Importantly, peripheral stimuli are perceptually pre-processed before foveal vision arrives at the stimulus, and this pre-processing speeds foveal processing (Alvarez & Oliva, 2009;Henderson et al, 1989;Henderson, 1992;Henderson and Hollingworth, 2003;Hughes et al, 2016). This would suggest that the reduced pictorial advantage in target and distractor dwell times, and the absence of a pictorial advantage in guidance in the spatial frequency condition, may arise due to less efficient peripheral pre-processing of high-spatial frequency information.…”

“…However, it is important to note these measures do not perfectly delineate target and distractor processing. Given that attention is known to "scout ahead" and peripherally preprocess stimuli that the eye will saccade towards (Alvarez & Oliva, 2009; Henderson, Pollastek, & R a y n e r , 1 9 8 9 ; H e n d e r s o n , 1 9 9 2 ; H e n d e r s o n & Hollingsworth, 2003;Hughes, Southwell, Gilchrist, & Tolhurst, 2016), this creates a dependency between foveal and peripheral processing. Likewise, information processed by foveal vision often gives cues about the broader context of the search display and can influence eye movements to peripheral locations.…”