  To investigate whether the vanishing point (VP) plays a significant role in
gaze guidance, we ran two experiments. In the first one, we recorded fixations
of 10 observers (4 female; mean age 22; SD=0.84) freely viewing 532 images, out
of which 319 had VP (shuffled presentation; each image for 4 secs). We found
that the average number of fixations at a local region (80x80 pixels) centered
at the VP is significantly higher than the average fixations at random
locations (t-test; n=319; p=1.8e-35). To address the confounding factor of
saliency, we learned a combined model of bottom-up saliency and VP. AUC score
of our model (0.85; SD=0.01) is significantly higher than the original saliency
model (e.g., 0.8 using AIM model by Bruce & Tsotsos (2009), t-test; p=
3.14e-16) and the VP-only model (0.64, t-test; p= 4.02e-22). In the second
experiment, we asked 14 subjects (4 female, mean age 23.07, SD=1.26) to search
for a target character (T or L) placed randomly on a 3x3 imaginary grid
overlaid on top of an image. Subjects reported their answers by pressing one of
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 target happened inside the cell containing the VP compared to
cells without VP (median across 14 subjects 1.34 sec vs. 1.96; Wilcoxon
rank-sum test; p = 0.0014). Response time at VP cells were also significantly
lower than response time on images without VP (median 2.37; p= 4.77e-05). These
findings support the hypothesis that vanishing point, similar to face and text
(Cerf et al., 2009) as well as gaze direction (Borji et al., 2014) attracts
attention in free-viewing and visual search.
