Journal of Vision最新文献

Previous studies have elucidated that humans can implicitly process faces faster than they process objects. However, the mechanism through which the brain unconsciously processes ambiguous facial images remains unclear. In our experiment, upright and inverted black-and-white binary face stimuli were presented in a two-alternative forced-choice location discrimination task combined with continuous flash suppression, a technique that suppresses visual stimuli perception using rapidly changing masks. The breaking time (BT) or the time required for a stimulus to be perceptually recognized was recorded for each face stimulus. The results showed that the BT for inverted grayscale images was significantly longer than that for upright grayscale faces, whereas the BT for upright and inverted binary faces did not reach statistical significance. A significant correlation between face likeness and BT was established after evaluating face likeness for each binary face stimulus, with high-face-like binary faces exhibiting shorter BT and low-face-like stimuli resulting in a more prolonged BT. Our results suggest that even an ambiguous object rated highly in face likeness can reduce the BT under implicit processing, indicating the possibility that facial parts such as the eyes and nose are subconsciously detected in ambiguous facial stimuli, enabling facial perception.

Serial dependence refers to a common misperception that can occur between subsequently observed stimuli. Observers misreport the current stimulus as being more similar to the previous stimulus than it objectively is. It has been proposed that this bias may reflect an attraction of the current percept to prior percept (Fischer & Whitney, 2014). Alternatively, serial dependence has also been proposed to be the result of an assimilative effect between observer decisions (Fritsche, Mostert, & de Lange, 2017; Pascucci, Mancuso, Santandrea, Libera, Plomp, & Chelazzi, 2019). Lying within this debate is the issue of how we quantify serial dependence. Should this be as a bias induced by prior stimuli or by prior responses? We investigated this by manipulating the orientation of the current stimuli such that they fell between previous stimulus and previous response. We observed an attraction to previous response and a concomitant repulsion from previous stimulus. This suggests that the attractive effect of serial dependence in orientation judgments is best quantified in relation to prior response.

When target and distractor stimuli are close together, they activate the same neurons and there is ambiguity as to what the neural activity represents. It has been suggested that the ambiguity is resolved by spatial competition between target and nontarget stimuli. A competitive advantage is conveyed by bottom-up biases (e.g., stimulus saliency) and top-down biases (e.g., the match to a stored representation of the target stimulus). Here, we tested the hypothesis that regions with high perceptual performance may provide a bottom-up bias, resulting in increased distractor interference. Initially, we focused on two known anisotropies. At equal distance from central fixation, perceptual performance is better along the horizontal than the vertical meridian, and in the lower than in the upper visual hemifield. Consistently, interference from distractors on the horizontal meridian was greater than interference from distractors on the vertical meridian. However, distractors in the lower hemifield interfered less than distractors in the upper visual hemifield, which is contrary to the known anisotropy. These results were obtained with targets and distractors on opposite meridians. Further, we observed greater interference from distractors on the meridians compared with distractors on the diagonals, possibly reflecting anisotropies in attentional scanning. Overall, the results are only partially consistent with the hypothesis that distractor interference is larger for distractors on regions with high perceptual performance.

Our aim in this study was to understand how we perform visuospatial comparison tasks by analyzing ocular behavior and to examine how restrictions in macular or peripheral vision disturb ocular behavior and task performance. Two groups of 18 healthy participants with normal or corrected visual acuity performed visuospatial comparison tasks (computerized version of the elementary visuospatial perception [EVSP] test) (Pisella et al., 2013) with a gaze-contingent mask simulating either tubular vision (first group) or macular scotoma (second group). After these simulations of pathological conditions, all participants also performed the EVSP test in full view, enabling direct comparison of their oculomotor behavior and performance. In terms of oculomotor behavior, compared with the full view condition, alternation saccades between the two objects to compare were less numerous in the absence of peripheral vision, whereas the number of within-object exploration saccades decreased in the absence of macular vision. The absence of peripheral vision did not affect accuracy except for midline judgments, but the absence of central vision impaired accuracy across all visuospatial subtests. Besides confirming the crucial role of the macula for visuospatial comparison tasks, these experiments provided important insights into how sensory disorder modifies oculomotor behavior with or without consequences on performance accuracy.

Most research on visual search has used simple tasks presented on a computer screen. However, in natural situations visual search almost always involves eye, head, and body movements in a three-dimensional (3D) environment. The different constraints imposed by these two types of search tasks might explain some of the discrepancies in our understanding concerning the use of memory resources and the role of contextual objects during search. To explore this issue, we analyzed a visual search task performed in an immersive virtual reality apartment. Participants searched for a series of geometric 3D objects while eye movements and head coordinates were recorded. Participants explored the apartment to locate target objects whose location and visibility were manipulated. For objects with reliable locations, we found that repeated searches led to a decrease in search time and number of fixations and to a reduction of errors. Searching for those objects that had been visible in previous trials but were only tested at the end of the experiment was also easier than finding objects for the first time, indicating incidental learning of context. More importantly, we found that body movements showed changes that reflected memory for target location: trajectories were shorter and movement velocities were higher, but only for those objects that had been searched for multiple times. We conclude that memory of 3D space and target location is a critical component of visual search and also modifies movement kinematics. In natural search, memory is used to optimize movement control and reduce energetic costs.

The preferred retinal locus (PRL) is the position on the retina to which humans direct stimuli during fixation. In healthy normal eyes, it has been shown to be very stable across time and between different tasks. Previous measurements of the PRL have been made under monocular viewing conditions. The current study examines where the PRLs in the two eyes' retinas are when subjects fixate binocularly and whether they shift when the demand for the eyes to converge is changed. Our apparatus allows us to see exactly where binocular stimuli fell on the two retinas during binocular fixation. Thus, our technique bypasses some of the issues involved in measuring binocular alignment with subjective techniques and previous objective techniques that use conventional eye trackers. These results show that PRLs shift slightly but systematically as the demand for convergence increases. The shifts cause under-convergence (also called exo fixation disparity) for near targets. They are not large enough to cause a break in binocular fusion. The fixation disparity we observed with increasing vergence demand is similar to fixation disparity observed in previous reports.