There is a consistent left-gaze bias when observers fixate upright faces, but it is unknown how this bias manifests in rotated faces, where the two eyes appear at different heights on the face. In two eye-tracking experiments, we measured participants’ first and second fixations, while they judged the expressions of upright and rotated faces. We hypothesized that rotated faces might elicit a bias to fixate the upper eye. Our results strongly confirmed this hypothesis, with the upper eye bias completely dominating the left-gaze bias in ±45° faces in Experiment 1, and across a range of face orientations (±11.25°, ±22.5°, ±33.75°, ±45°, and ±90°) in Experiment 2. In addition, rotated faces elicited more overall eye-directed fixations than upright faces. We consider potential mechanisms of the upper eye bias in rotated faces and discuss some implications for research in social cognition.

There is a well-known left-gaze bias when looking at faces: the left side of the face (from the point of view of the observer) receives more first fixations and has a greater influence on perceptual decisions than the right side of the face (Campbell, 1978; Guo et al., 2009). Here we investigated whether the in-plane orientation of a face image influences the left-gaze bias. In Experiment 1, we developed an expression classification task that elicited a strong left-gaze bias in upright faces, regardless of whether face images had been mirror-reversed (ruling out stimulus effects). In Experiment 2, a new group of participants completed the same task on faces that were presented either upright, rotated clockwise by 45°, or counterclockwise by 45°, while their eye movements were being tracked. We predicted that in addition to a left-gaze bias to upright faces, participants might show an upper eye bias to tilted faces, manifesting as more first fixations to the left eye of clockwise-rotated faces, but more first fixations to the right eye of counterclockwise-rotated faces. Our findings confirmed this prediction; in fact, the tendency to fixate the upper eye in rotated faces completely dominated any lateral bias (Figure 1A). In Experiment 2, we tested additional orientations (0°, ±11.25°, ±22.5°, ±33.75°, ±45°, ±90°, and 180°) to determine at what angle this upper-eye bias overrides the left-gaze bias. To our surprise, even a small counterclockwise tilt of 11.25° was sufficient to eliminate the left-gaze bias, with the upper eye bias peaking for ±45° faces (Figure 1B). We consider a potential mechanism for this upper eye bias in light of recent findings (de Haas et al., 2016) showing that cortical responses to facial features are enhanced when features appear in canonical positions relative to fixation. Meeting abstract presented at VSS 2018

The visual image provides important cues for an observer’s sense of location and orientation within the world. Occasionally, though, these cues can be misleading, resulting in illusions. In the Roelofs and induced Roelofs effects, for example, a large illuminated frame, offset from the observer’s midline in otherwise complete darkness, tends to bias the observer’s judgment of straight ahead, causing the position of the frame, and anything contained within it, to be misperceived. Studies of these illusions have provided much insight into the processes that establish an observer’s egocentric reference frame, and the manner in which object locations are encoded relative to this frame for perception and action.

The need to protect our environment is urgent, and psychology can contribute to accomplishing this goal. Combating climate change, resource exhaustion, species extinction, and other problems is an admirable goal, but such efforts will fail in the long run if the population growth that creates or exacerbates the other problems is not addressed. The large and growing human population inevitably demands more and more resources. In this comment on Clayton et al. (2016), the author proposes that psychology can identify reasons why the underlying population issue is not adequately addressed and can suggest ways to improve the situation. (PsycINFO Database Record

SIGNIFICANCE:Increasing evidence indicates that childhood binocular vision disorders that lead to stereodeficiency may be treated in adulthood. Reports of patients who gain stereopsis as adults indicate that this achievement provides for a qualitatively different and dramatically improved sense of space and depth.PURPOSE:Increasing evidence suggests that stereopsis can be achieved in adult patients despite long-standing binocular disorders. We polled individuals who gained stereopsis as adults to ascertain their initial binocular disorders, the length of time they were stereodeficient, effective treatments, and the nature of their recovered stereovision.METHODS:A questionnaire was posted online and announced in a brief article in the journal Vision Development and Rehabilitation.RESULTS:Of the 63 responders, 56 (89%) reported strabismus and/or amblyopia, and 55 (87%) indicated that they had been stereodeficient for as long as they could remember. All but seven participants (89%) achieved stereovision through vision training or a combination of surgery and vision training, and many reported vivid visual changes.CONCLUSIONS:Despite childhood binocular disorders, patients may be able to achieve stereopsis following interventions in adulthood. This achievement provides for a qualitatively different and dramatically improved sense of space and depth.

During saccadic eye movements, the job of the nervous system is not to perceive a change in stimulation from the receptors, but to prevent a change from reaching consciousness. These movements occupy an intermediate range between actions that are almost always conscious, such as finger movements, and those that are never conscious, such as the smooth-muscle actions of the digestive system. Consciousness in this context requires attention to the consequences of an action.

We provide empirical examples to conceptually clarify some items on Firestone & Scholl's (F&S's) checklist, and to explain perceptual effects from an attentional and memory perspective. We also note that action and embodied cognition studies seem to be most susceptible to misattributing attentional and memory effects as perceptual, and identify four characteristics unique to action studies and possibly responsible for misattributions.

Successful motor interaction with a target changes memory of the target’s size, which seems larger if the action was successful than if it was unsuccessful. This has been attributed to the effect of action on subsequent perception or memory. We asked what the action provides: Is feedback from the action necessary, or only the information provided by the action? We found that perceived difficulty alone changes the remembered goal characteristics, without changes in the stimuli, and before the motor task is executed. We gave observers a marble and showed them a hole in a box. They were told that throwing the marble into the hole was either difficult or easy, depending on the condition. The hole was then covered and its size judged. Participants who were told that the task was difficult judged the hole to be significantly smaller than it was, whereas those told that the task was easy made judgements not significantly different from veridical. When observers subsequently threw the marble, their success rates were independent of their own estimates of hole size or of what they had been told about the difficulty of the task, showing that their size estimates affected memory but not action. In a second experiment, we found that the effect disappeared if the hole was visible during the size estimation.

Several studies have shown that slopes of hills are greatly overestimated. We have recently demonstrated that the overestimates increase logarithmically as the end point of the domain to be estimated increases – every doubling of the distance to the end point results in a constant increment in perceived slope. A theoretical analysis showed that a critical parameter is the angle v between the observer’s line of sight and the slope of the hill, when the observer fixates the far point of the required domain. The theory predicts that increasing observers’ eye height above the surface of the hill will reduce the slope overestimates by increasing this angle. Here we test that theory by having observers stand on a 37 cm high box to increase their eye height. Observers estimated an outdoor slope in front of them in degrees, at ranges from 2 to 16 m. Estimates for various ranges defined by traffic cones again followed a logarithmic function (r2 = 0.997), with lower estimates compared to other observers standing directly on the surface of the hill. Apparent slope increased more rapidly with distance than in a group standing on the hill’s surface, however, so that at larger distances slope estimates with and without increased eye height converged. As the length of the domain to be judged increases, enhanced eye height has a smaller and smaller effect on the angle v between the line of regard and the hill’s surface. A demand characteristic might induce observers to give different estimates for the four distances tested; an analysis of just the first estimate of each observer, however, showed that the distance vs apparent slope function remained logarithmic. We conclude that anticipated effort, perceived danger and other factors play only a minor role if any in slope estimates. Meeting abstract presented at VSS 2015

Vision Development & Rehabilitation Volume 1, Issue 1 • April 2015 In recent years it has become clear that those born with deficient stereoscopic vision can acquire this capacity as adults under some circumstances. Sue Barry, who had no measurable stereopsis, acquired better than 100 arcseconds of stereoacuity following one year of optometric vision therapy (Barry, 2009). Bruce Bridgeman experienced stereopsis after viewing the film “Hugo” in 3D (Bridgeman, 2014), an ability that has endured for more than two years. Fortunately, professionally measured stereoscopic thresholds were available for periods both before and after the Hugo experience; static stereoacuity improved from 200 arc seconds on Wirt Circles before the experience to 80 are seconds afterward. Media reports on CNN, BBC and other sources resulted in emails from people all over the world who had similar experiences. This raises the possibility that some patients viewing a 2-hour film in stereoscopic 3D might experience benefits such as those gained through more formalized therapy. For future clinical interventions it is important to know for the recovered patients both what kinds of visual anomalies resulted in poor stereopsis, and what kinds of experiences triggered acquisition of stereopsis. To investigate this further, Bridgeman has created a survey to document the experiences of those who had acquired stereopsis. To extend this survey to the maximum number of patients, we are asking optometrists and other vision professionals to offer the survey to patients who have acquired stereopsis, either through formal training or informal experience such as viewing a 3D film. The survey is available online at http://bit.ly/1vThYaM.

Several studies have shown that slopes of hills are greatly overestimated. We have recently demonstrated that the overestimates increase logarithmically as the end point of the domain to be estimated is increased. A theoretical analysis showed that a critical parameter is the angle between the observer's line of sight and the slope of the hill, when the observer fixates the far point of the required domain. The theory predicts that increasing the observers' eye height will increase this angle, thus reducing the overestimates. Here, we test that theory by having observers stand on a box to increase their eye height. Slope estimates for various ranges again followed a logarithmic function, with lower estimates at nearer distances compared with other observers standing directly on the surface of the hill. At larger distances, slope estimates with and without increased eye height converged.

The ability to read emotional information from a face has clear evolutionary advantages for social animals. Recent research shows that humans have a gaze bias towards the left side of a face image (the right side of the face), and this bias might be controlled by the emotional content of the face. This might be due to more emotional expression on the right side of the face. Since canines have been co-evolving with humans for thousands of years, we might process canine faces in a similar manner. We investigated lateral gaze bias to photographs of objects, human faces, and dog faces. If gaze bias is based on a fixed preference to inspect the right side of the face more then the left, left-right reversal of the face should not have an effect. We found that reversing the image did not change the scanpath for either dogs or human faces, but there was a significant bias to look more on the left side of the image for dog faces than human faces. This suggests that when a face is thought to express more emotion, there is more left bias for the image, not specifically the right side of the original face. We found no support for the alternative hypothesis that the decision about where to concentrate the gaze is determined in real time by immediately available cues. Rather, the right-face bias is hard-wired. Meeting abstract presented at VSS 2014

The slopes of hills tend to be greatly overestimated. Previous studies have found that slope estimates are significantly greater when estimated verbally than with a proprioceptive measure. It has yet to be determined whether these estimates are made for the entire extent of the slope, or whether the estimates in closest proximity are estimated using a different process. Since some parietal cortex neurons respond differently to objects within arm's reach, short-distance slope estimation may utilize these or analogous neurons. Alternatively, greater implied effort might make longer slopes seem steeper. We determined that both verbal and proprioceptive reports of slope are overestimates that increase logarithmically with distance from the observer, contradicting both theories. Consistent with previous work, proprioceptive estimates were more accurate at all ranges. Our results can be interpreted as a function of the angle between the observer's gaze and the plane of the hill, modified by depth cues available at only near distances.

Objective: We propose and test a method to reduce simulator sickness. Background: Prolonged work in driving simulators often leads to nausea and other symptoms summarized as simulator sickness. Visual/vestibular mismatches are a frequently addressed cause; we investigate another possibility, mismatch between actual distance to a screen and depicted distances in the simulator’s graphics. Method: Drivers negotiated a figure-8 course in a photorealistic simulator. They reported discomfort and vection every 10 minutes up to 40 min. A correction group wore optometric test frames with +1.75 diopter lenses and prisms to converge parallel lines of sight on a screen 56 cm from the driver’s eyes, preserving the normal accommodative convergence–to–accommodation (AC/A) ratio. A control group wore neutral lenses in the same test frames. In other experiments head tilt simulated vestibular experience on curves. Results: The optical correction significantly reduced simulator sickness measured on a 10-point discomfort scale, where 1 is no problem and 10 is about to vomit. Vection ratings were similar for correction and control groups. Some drivers failed to complete the course because of high discomfort ratings, crashes, or other causes. Head tilt in the direction opposite each curve while wearing the correction did not affect discomfort, while tilt in the same direction as each curve made simulator sickness worse. Conclusion: Optical corrections can significantly reduce simulator sickness, though they do not eliminate it. Head tilt while driving is not recommended. Application: Simple optical corrections in spectacle frames, easily purchased at any optical facility, should be used in screen-based driving simulators. Strength of the correction depends on distance from the driver to the screen.

In February 2012, the author acquired improved stereoscopic vision after viewing Martin Scorsese's film Hugo in 3D. The author had been deficient in stereo vision all of his life because in the first two decades, one eye deviated outward from the gaze position of the other. At that time, he was an alternator (alternating exotrope) showing strabismus (>20 prism diopters) without amblyopia. After viewing the 2-hour film, the Wirt stereo threshold decreased from 200 to 80 arcsec, and stereoscopic vision became a vivid experience. Exophoria decreased to 7 prism diopters. Numerous personal and research experiences throughout the author's career helped to interpret the phenomenon, which suggests a powerful new method for treating stereo-deficient patients.

We investigated the physiological mechanism of grapheme–color synesthesia using metacontrast masking. A metacontrast target is rendered invisible by a mask that is delayed by about 60 ms; the target and mask do not overlap in space or time. Little masking occurs, however, if the target and mask are simultaneous. This effect must be cortical, because it can be obtained dichoptically. To compare the data for synesthetes and controls, we developed a metacontrast design in which nonsynesthete controls showed weaker dichromatic masking (i.e., the target and mask were in different colors) than monochromatic masking. We accomplished this with an equiluminant target, mask, and background for each observer. If synesthetic color affected metacontrast, synesthetes should show monochromatic masking more similar to the weak dichromatic masking among controls, because synesthetes could add their synesthetic color to the monochromatic condition. The target–mask pairs used for each synesthete were graphemes that elicited strong synesthetic colors. We found stronger monochromatic than dichromatic U-shaped metacontrast for both synesthetes and controls, with optimal masking at an asynchrony of 66 ms. The difference in performance between the monochromatic and dichromatic conditions in the synesthetes indicates that synesthesia occurs at a later processing stage than does metacontrast masking.