Vanishing point attracts gaze in free-viewing and visual search tasks

Abstract

Several structural scene cues such as gist, layout, horizontal line, openness, and depth have been shown to guide scene perception (e.g., Oliva & Torralba, 2001); Ross & Oliva, 2009). Here, to investigate whether vanishing point (VP) plays a significant role in gaze guidance, we ran two experiments. In the first one, we recorded fixations of 10 observers (six male, four female; mean age 22; SD = 0.84) freely viewing 532 images, out of which 319 had a VP (shuffled presentation; each image for 4 s). We found that the average number of fixations at a local region (80 × 80 pixels) centered at the VP is significantly higher than the average fixations at random locations (t test; n = 319; p < 0.001). To address the confounding factor of saliency, we learned a combined model of bottom-up saliency and VP. The AUC (area under curve) score of our model (0.85; SD = 0.01) is significantly higher than the base saliency model (e.g., 0.8 using attention for information maximization (AIM) model by Bruce & Tsotsos, 2005, t test; p = 3.14e-16) and the VP-only model (0.64, t test; p < 0.001). In the second experiment, we asked 14 subjects (10 male, four female; mean age 23.07, SD = 1.26) to search for a target character (T or L) placed randomly on a 3 × 3 imaginary grid overlaid on top of an image. Subjects reported their answers by pressing one of the two keys. Stimuli consisted of 270 color images (180 with a single VP, 90 without). The target happened with equal probability inside each cell (15 times L, 15 times T). We found that subjects were significantly faster (and more accurate) when the target appeared inside the cell containing the VP compared to cells without the VP (median across 14 subjects 1.34 s vs. 1.96 s; Wilcoxon rank-sum test; p = 0.0014). These findings support the hypothesis that vanishing point, similar to face, text (Cerf, Frady, & Koch, 2009), and gaze direction Borji, Parks, & Itti, 2014) guides attention in free-viewing and visual search tasks.

Eye Movements Converge on Vanishing Points during Visual Search

“…The results of Experiment 1 revealed that vanishing points capture eye movements during free‐viewing task, and suggest that vanishing points may provide significant information, and support findings of the previous studies (Borji et al, ; Feng et al, ). However, this effect was weaker when natural scenes were presented.…”

“…This is not specific to humans: predator animals search for food while moving, and prey animals must move to avoid the predator and to find their food. Although previous studies have shown that vanishing points and source points of optical flow, which guide our moving direction, capture attention (Borji & Feng, ; Feng et al, ; Wang, Fukuchi, Koch, & Tsuchiya, ), this study is the first to empirically show that this effect continues to influence eye movements while individuals are performing tasks irrelevant to vanishing points using actual photographs and artificial controlled backgrounds.…”

“…The purpose of this experiment was to investigate whether eye movements converge on the vanishing point during a free‐viewing task described in previous studies (Borji et al, ; Feng et al, ), and to establish whether our original photographs were appropriate for the experiment. Compared with manmade scenes, the vanishing point in natural scenes rarely appears.…”

“…From the physiological perspective, this idea is supported by the fact of cortical magnification: the number of neurons in the visual cortex responsible for central vision is larger than that responsible for peripheral vision. Actually, although a vanishing point does not always indicate high saliency within scenes, a model combining saliency and vanishing points facilitates the prediction of human eye fixations during a free‐viewing task (Borji, Feng, & Lu, ; Feng, Borji, & Lu, ). Since seeing a vanishing point is suited to understanding the whole scene at a glance, it would also be advantageous in situations that require understanding the whole scene as soon as possible.…”

“…Search in visual field while attending to a moving direction is ecologically valid because individuals often search while moving. Borji and Feng () empirically demonstrated that the target around the vanishing point was easy to find. In addition to behavioral results, we investigated convergence of eye movement on the vanishing point during search.…”