The use of optimal object information in fronto-parallel orientation discrimination

AbstractWhen determining an object’s orientation an implicit object axis is formed, based on local contour information. Due to the oblique effect (i.e., the more precise perception of horizontal/vertical orientations than oblique orientations), an object’s orientation will be perceived more precise if the axis is either horizontal or vertical than when the axis is oblique. In this study we investigated which object axis is used to determine orientation for objects containing multiple axes. We tested human subjects in a series of experiments using the method of adjustment. We found that observers always use object axes allowing for the highest object orientation discrimination, namely the axes lying closest to the horizontal/vertical. This implies that the weight the visual system attaches to axial object information is in accordance with the precision with which this information is perceived

Goal-directed visual attention drives health goal priming: an eye-tracking experiment

Objective: Several lab and field experiments have shown that goal priming interventions can be highly effective in promoting healthy food choices. Less is known, however, about the mechanisms by which goal priming affects food choice. This experiment tested the hypothesis that goal priming affects food choices through changes in visual attention. Specifically, it was hypothesized that priming with the dieting goal steers attention toward goal-relevant, low energy food products, which, in turn, increases the likelihood of choosing these products. Methods: In this eye-tracking experiment, 125 participants chose between high and low energy food products in a realistic online supermarket task while their eye movements were recorded with an eye-tracker. One group was primed with a health and dieting goal, a second group was exposed to a control prime, and a third group was exposed to no prime at all. Results: The health goal prime increased low energy food choices and decreased high energy food choices. Furthermore, the health goal prime resulted in proportionally longer total dwell times on low energy food products, and this effect mediated the goal priming effect on choices. Conclusions: The findings suggest that the effect of priming on consumer choice may originate from an increase in attention for prime-congruent items. This study supports the effectiveness of health goal priming interventions in promoting healthy eating and opens up directions for research on other behavioral interventions that steer attention toward healthy foods

Searching with and against each other: Spatiotemporal coordination of visual search behavior in collaborative and competitive settings

Although in real life people frequently perform visual search together, in lab experiments this social dimension is typically left out. Here, we investigate individual, collaborative and competitive visual search with visualization of search partners' gaze. Participants were instructed to search a grid of Gabor patches while being eye tracked. For collaboration and competition, searchers were shown in real time at which element the paired searcher was looking. To promote collaboration or competition, points were rewarded or deducted for correct or incorrect answers. Early in collaboration trials, searchers rarely fixated the same elements. Reaction times of couples were roughly halved compared with individual search, although error rates did not increase. This indicates searchers formed an efficient collaboration strategy. Overlap, the proportion of dwells that landed on hexagons that the other searcher had already looked at, was lower than expected from simulated overlap of two searchers who are blind to the behavior of their partner. The proportion of overlapping dwells correlated positively with ratings of the quality of collaboration. During competition, overlap increased earlier in time, indicating that competitors divided space less efficiently. Analysis of the entropy of the dwell locations and scan paths revealed that in the competition condition, a less fixed looking pattern was exhibited than in the collaborate and individual search conditions. We conclude that participants can efficiently search together when provided only with information about their partner's gaze position by dividing up the search space. Competing search exhibited more random gaze patterns, potentially reflecting increased interaction between searchers in this condition

Brief Report: Eye Movements During Visual Search Tasks Indicate Enhanced Stimulus Discriminability in Subjects with PDD

Subjects with PDD excel on certain visuo-spatial tasks, amongst which visual search tasks, and this has been attributed to enhanced perceptual discrimination. However, an alternative explanation is that subjects with PDD show a different, more effective search strategy. The present study aimed to test both hypotheses, by measuring eye movements during visual search tasks in high functioning adult men with PDD and a control group. Subjects with PDD were significantly faster than controls in these tasks, replicating earlier findings in children. Eye movement data showed that subjects with PDD made fewer eye movements than controls. No evidence was found for a different search strategy between the groups. The data indicate an enhanced ability to discriminate between stimulus elements in PDD

Окказионализмы vs неологизмы: критерии перехода

Статья посвящена проблеме новообразований современного английского языка: уточнению понятий "новообразование", "окказионализм" и "неологизм", проблеме их идентификации и стратификации. В работе предпринята попытка унификации существующего терминологического аппарата, используемого для разграничения разных типов новообразований в разговорной речи и литературных произведениях. Кроме того, в статье предложена система критериев идентификации новообразований, и рассмотрены условия перехода окказионализмов в неологизмы.Стаття присвячена проблемі новоутворень сучасної англійської мови: уточненню понять "новоутворення", "оказіоналізм" та "неологізм", проблемі їх ідентифікації та стратифікації. У роботі здійснюється спроба уніфікувати існуючий термінологічний апарат, що використовується для розмежування різних типів новоутворень у розмовній мові та літературних творах. Крім того, в статті запропонована система критеріїв ідентифікації новоутворень, а також розглянуті умови переходу оказіоналізмів у неологізми.The article is devoted to the problem of new-formations in Modern English, namely to specifying of such notions as "new-formations", "nonce-words" and "neologisms", to the problem of their identification and stratification. There was made an attempt in the research under consideration to unify the system of already existing terminology that is used to differentiate different types of new-formations in speech and in literary works. Besides an original system of criteria was suggested in the article to identify different types of new-formations and the conditions giving the opportunity to nonce-words to get the status of neologisms

Saccadic selection and crowding in visual search:stronger lateral masking leads to shorter search times

We investigated the role of crowding in saccadic selection during visual search. To guide eye movements, often information from the visual periphery is used. Crowding is known to deteriorate the quality of peripheral information. In four search experiments, we studied the role of crowding, by accompanying individual search elements by flankers. Varying the difference between target and flankers allowed us to manipulate crowding strength throughout the stimulus. We found that eye movements are biased toward areas with little crowding for conditions where a target could be discriminated peripherally. Interestingly, for conditions in which the target could not be discriminated peripherally, this bias reversed to areas with strong crowding. This led to shorter search times for a target presented in areas with stronger crowding, compared to a target presented in areas with less crowding. These findings suggest a dual role for crowding in visual search. The presence of flankers similar to the target deteriorates the quality of the peripheral target signal but can also attract eye movements, as more potential targets are present over the area

Perceiving slant about a horizontal axis from stereopsis

Rotating a surface about a horizontal axis alters the retinal horizontal-shear disparities. Opposed torsional eye movements (cyclovergence) also change horizontal shear. If there were no compensation for the horizontal disparities created by cyclovergence, slant estimates would be erroneous. We asked whether compensation for cyclovergence occurs, and, if it does, whether it occurs by use of an extraretinal cyclovergence signal, by use of vertical-shear disparities, or by use of both signals. In four experiments, we found that compensation is nearly veridical when verticalshear disparities are available and easily measured. When they are not available or easily measured, no compensation occurs. Thus, the visual system does not seem to use an extraretinal cyclovergence signal in stereoscopic slant estimation. We also looked for evidence of an extraretinal cyclovergence signal in a visual direction task and found none. We calculated the statistical reliabilities of slant-from-disparity and slant-from-texture estimates and found that the more reliable of the two means of estimation varies significantly with distance and slant. Finally, we examined how slant about a horizontal axis might be estimated when the eyes look eccentrically

Fixation classification: how to merge and select fixation candidates

Eye trackers are applied in many research fields (e.g., cognitive science, medicine, marketing research). To give meaning to the eye-tracking data, researchers have a broad choice of classification methods to extract various behaviors (e.g., saccade, blink, fixation) from the gaze signal. There is extensive literature about the different classification algorithms. Surprisingly, not much is known about the effect of fixation and saccade selection rules that are usually (implicitly) applied. We want to answer the following question: What is the impact of the selection-rule parameters (minimal saccade amplitude and minimal fixation duration) on the distribution of fixation durations? To answer this question, we used eye-tracking data with high and low quality and seven different classification algorithms. We conclude that selection rules play an important role in merging and selecting fixation candidates. For eye-tracking data with good-to-moderate precision (RMSD < 0.5∘), the classification algorithm of choice does not matter too much as long as it is sensitive enough and is followed by a rule that selects saccades with amplitudes larger than 1.0∘ and a rule that selects fixations with duration longer than 60 ms. Because of the importance of selection, researchers should always report whether they performed selection and the values of their parameters