Extraretinal and retinal amplitude and phase errors during Filehne illusion and path perception

Pursuit eye movements give rise to retinal motion. To judge stimulus motion relative to the head, the visual system must correct for the eye movement by using an extraretinal, eye-velocity signal. Such correction is important in a variety of motion estimation tasks including judgments of object motion relative to the head and judgments of self-motion direction from optic flow. The Filehne illusion (where a stationary object appears to move opposite to the pursuit) results from a mismatch between retinal and extraretinal speed estimates. A mismatch in timing could also exist. Speed and timing errors were investigated using sinusoidal pursuit eye movements. We describe a new illusion--the slalom illusion--in which the perceived direction of self-motion oscillates left and right when the eyes move sinusoidally. A linear model is presented that determines the gain ratio and phase difference of extraretinal and retinal signals accompanying the Filehne and slalom illusions. The speed mismatch and timing differences were measured in the Filehne and self-motion situations using a motion-nulling procedure. Timing errors were very small for the Filehne and slalom illusions. However, the ratios of extraretinal to retinal gain were consistently less than 1, so both illusions are the consequence of a mismatch between estimates of retinal and extraretinal speed. The relevance of the results for recovering the direction of self-motion during pursuit eye movements is discussed.     

The size illusion: visual and kinaesthetic information in size perception

Earlier studies have shown the size of kinaesthetically presented two-dimensional movement patterns to be significantly overestimated. Whether this size overestimation is characteristic of the kinaesthetic system alone has not been established. Two experiments are reported which were designed to investigate size judgment made after kinaesthetic and visual pattern presentation and the effect of environmental cues on the perception of movement patterns. In experiment 1 patterns were presented kinaesthetically (experimenter guided hand movements around the outline of the pattern) or in combination with visual information given by a moving light (pinpoint light attached to the stylus which was moved around the pattern); visual and kinaesthetic cues were either congruent or conflicting with each other; and environmental cues were either present or absent. In experiment 2 static visual display was compared with visually traced pattern presentation, again with or without environmental cues. Overall the results showed that, regardless of experimental manipulation, in all cases where the information was given over time the subject perceived the pattern larger than reality. After static visual display, overestimation of size did not occur.     

An illusion of movement complementary to the horizontal-vertical illusion

Blindfolded subjects moved a stylus held in the hand over a standard distance of 4.5 ins. in a given direction. They then attempted to move the same distance in a direction at right angles to the first. Eight combinations of movements were investigated. The results reveal an illusion such that the extent of movements to left or right across the body is underestimated, while the extent of movements towards or away from the body in the mid-line is overestimated. The illusion applies to speed as well as extent of movement. Movement up or down in a vertical plane is equivalent to movement towards or away from the body in a horizontal plane.

The interaction of this illusion with the well-known horizontal-vertical illusion of visual perception explains a failure to find any net illusory effect where lines visually displayed in different orientations were matched for length by unseen movements in similar orientations.

Whether the visual and movement illusions simply co-exist or whether they are functionally related is not yet clear.     

Effects of gaze angle and extraretinal eye movement information on visual locomotion control

This study tested effects of gaze-movement angle and extraretinal eye movement information on performance in a locomotion control task. Subjects hovered in a virtual scene to maintain position against optically simulated gusts. Gaze angle was manipulated by varying the simulated camera pitch orientation. Availability of extraretinal information was manipulated via simulated-pursuit fixation. In Experiment 1, subjects performed better when the camera faced a location on the ground than when it pointed toward the horizon. Experiment 2 tested whether this gain was influenced by availability of appropriate eye movements. Subjects performed slightly better when the camera pointed at nearby than at distant terrain, both in displays that did and in displays that did not simulate pursuit fixation. This suggested that subjects could perform the task using geometric image transformations, with or without appropriate eye movements. Experiment 3 tested more rigorously the relative importance of gaze angle and extraretinal information over a greater range of camera orientations; although subjects could use image transformations alone to control position adequately with a distant point of regard, they required eye movements for optimal performance when viewing nearby terrain.     

Some recent studies on the extraretinal contribution to distance perception

Some recent studies on the extraretinal contribution to distance perception are reviewed. These experiments demonstrate that vergence can provide reliable information for judgments on the distance of proximal targets in the absence of all other cues. We argue that, although vergence is an unreliable cue at large fixation distances and is subject to a strong contraction bias when studied in isolation, these facts do not imply a minor role for vergence in near-space perception. When additional depth and distance cues are added, the contribution of vergence information becomes more complicated. We present results which indicate that the different cues to depth and distance are combined in a manner that can result in unexpected distortions of visual space. A simple heuristic model which can produce the observed distortions is outlined.     

Time perception and the filled-duration illusion

A reproduction design is used to show that temporal intervals containing brief tones appear longer than empty intervals of the same duration, the effect being independent of duration. These and previous data are discussed within a theoretical framework which allows for the interrelation of data from different time perception tasks; and a reversible encoding model is stated which accounts for much of the data obtained with empty intervals. A “chunking” model, in which tones occurring in an interval serve to segment the interval during encoding, can account for the filled-duration illusion if certain conditions are met. Finally, mechanisms that are consistent with these conditions are stated.     

Manipulating basic taste perception to explore how product information affects experience

We introduce a novel physiologically-based methodology to consumer research—using the glycoprotein miraculin to manipulate the ability to sense and perceive specific taste elements in gustatory experiences. We apply this approach to exploring how information extrinsic (e.g., product reviews) to a product's inherent sensory facets influences reported consumption experiences and experienced utility. Results from two experiments suggest that extrinsic information distorts the basic sensory and perceptual character of consumption experiences, rather than simply biasing self-reports of the experiences or serving as an independent input to overall taste and utility evaluations. Such evaluations are distorted in the direction of extrinsic product information only when the ability to actually perceive the experience as being consistent with the extrinsic signal is not disrupted by miraculin. Conversely, disruption by miraculin of the ability to perceive an experience as being consistent with an extrinsic signal ablates or reverses such effects. Implications, applications to brands and branding, and other possible research directions for the miraculin taste-manipulation methodology are also discussed.     

The Ponzo illusion and the perception of orientation

A new theory, called the tilt constancy theory, claims that the Ponzo illusion is caused by the misperception of orientation induced by local visual cues. The theory relates the Ponzo illusion-along with the Z?llner, Poggendorff, Wündt-Hering, and cafe wall illusions-to the mechanisms that enable us to perceive stable orientations despite changes in retinal orientation or body orientation. In Experiment 1, the magnitude of the misperception of orientation was compared with the magnitude of the Ponzo illusion. In Experiment 2, predictions of the tilt constancy theory were compared with accounts based on (1) low spatial frequencies in the image, (2) memory comparisons (pool-and-store model), and (3) relative sizejudgments. In Experiment 3, predictions of the tilt constancy theory were tested against predictions of the assimilation theory of Pressey and his colleagues. In the final experiment, the orientation account was compared with theories based on linear perspective and inappropriate size constancy. The results support the tilt constancy theory.     

Visual and haptic perception of the horizontal-vertical illusion

The horizontal-vertical illusion consists of two lines of the same length (one horizontal and the other vertical) at a 90 degree angle from one another forming either an inverted-T or an L-shape. The illusion occurs when the length of a vertical line is perceived as longer than the horizontal line even though they are the same physical length. The illusion has been shown both visually and haptically. The present purpose was to assess differences between the visual or haptic perception of the illusions and also whether differences occur between the inverted-T and the L-shape illusions. The current study showed a greater effect in the haptic perception of the horizontal-vertical illusion than in visual perception. There is also greater illusory susceptibility of the inverted-T than the L-shape.     

Wheels: a new illusion in the perception of rolling objects

A new illusory effect is described which consists of a conspicuous perceptual overestimation of the speed at which a wheel rolling across an observer's visual field appears to be rotating. Wheels appear to revolve much faster than is compatible with their linear displacement. Experimental verification of the genuineness and magnitude of the effect is reported, along with a discussion of some of the variables upon which it may depend.     

Dissociating perception and action in Kanizsa's compression illusion

When a horizontally elongated surface is occluded in the middle by a larger surface, it appears narrower than its true width (Kanizsa’s compression illusion). We report that a similar compression effect occurs for closed-loop visuomotor matches of size, but not for otherwise comparable open-loop “mimed” reaching or size-matching visuomotor responses. Our study is the first in which a comparison of size perception in personal space with bilateral actions performed with both hands (instead of precision grips employing the thumb and the index finger) is used to investigate motor responses to Kanizsa’s compression illusion. Implications for the current debate on the existence of dissociations between spatial perception and visually controlled actions in personal space are discussed.     

Visual movement perception: A comparison of sensitivity to vertical and horizontal movement

A psychophysical model that provides separate measures of judgmental standards and sensitivity is utilized to compare an O’s visual sensitivity for vertical and horizontal movement. The analysis indicates no consistent difference in sensitivity; those asymmetries that do exist simply appear to be due to idiosyncratic judgmental standards.     

Roughness perception during the rubber hand illusion

Watching a rubber hand being stroked by a paintbrush while feeling identical stroking of one’s own occluded hand can create a compelling illusion that the seen hand becomes part of one’s own body. It has been suggested that this so-called rubber hand illusion (RHI) does not simply reflect a bottom–up multisensory integration process but that the illusion is also modulated by top–down, cognitive factors. Here we investigated for the first time whether the conceptual interpretation of the sensory quality of the visuotactile stimulation in terms of roughness can influence the occurrence of the illusion and vice versa, whether the presence of the RHI can modulate the perceived sensory quality of a given tactile stimulus (i.e., in terms of roughness). We used a classical RHI paradigm in which participants watched a rubber hand being stroked by either a piece of soft or rough fabric while they received synchronous or asynchronous tactile stimulation that was either congruent or incongruent with respect to the sensory quality of the material touching the rubber hand. (In)congruencies between the visual and tactile stimulation did neither affect the RHI on an implicit level nor on an explicit level, and the experience of the RHI in turn did not cause any modulations of the felt sensory quality of touch on participant’s own hand. These findings first suggest that the RHI seems to be resistant to top–down knowledge in terms of a conceptual interpretation of tactile sensations. Second, they argue against the hypothesis that participants own hand tends to disappear during the illusion and that the rubber hand actively replaces it.     

The illusion of fame: how the nonfamous become famous

This article reports 2 experiments in which nonfamous faces were paired with famous (e.g., Oprah Winfrey) or semifamous (e.g., Annika Sorenstam) faces during an initial orienting task. In Experiment 1, the orienting task directed participants to consider the relationship between the paired faces. In Experiment 2, participants considered distinctive qualities of the paired faces. Participants then judged the fame level of old and new nonfamous faces, semifamous faces, and famous faces. Pairing a nonfamous face with a famous face resulted in a higher fame rating than pairing a nonfamous face with a semifamous face. The fame attached to the famous people was misattributed to their nonfamous partners. We discuss this pattern of results in the context of current theoretical explanations of familiarity misattributions.     

Cues to intention: the role of movement information

Body movement provides a rich source of cues about other people’s goals and intentions. In the present research, we investigate how well people can distinguish between different social intentions on the basis of movement information. Participants observed a model reaching toward and grasping a wooden block with the intent to cooperate with a partner, compete against an opponent, or perform an individual action. In Experiment 1, a temporal occlusion procedure was used as to determine whether advance information gained during the viewing of the initial phase of an action allowed the observers to discriminate across movements performed with different intentions. In Experiment 2, we examined what kind of cues observers relied upon for the discrimination of intentions by masking selected spatial areas of the model (i.e., the arm or the face) maintaining the same temporal occlusion as for Experiment 1. Results revealed that observers could readily judge whether the object was grasped with the intent to cooperate, compete, or perform an individual action. Seeing the arm was better than seeing the face for discriminating individual movements performed at different speeds (natural-speed vs. fast-speed individual movements). By contrast, seeing the face was better than seeing the arm for discriminating social from individual movements performed at a comparable speed (cooperative vs. natural-speed individual movements, competitive vs. fast-speed individual movements). These results demonstrate that observers are attuned to advance movement information from different cues and that they can use such kind of information to anticipate the future course of an action.     

Anisotropic perception of visual angle: Implications for the horizontal-vertical illusion,overconstancy of size,and the moon illusion

Three experiments investigated anisotropic perception of visual angle outdoors. In Experiment 1, scales for vertical and horizontal visual angles ranging from 20° to 80° were constructed with the method of angle production (in which the subject reproduced a visual angle with a protractor) and the method of distance production (in which the subject produced a visual angle by adjusting viewing distance). In Experiment 2, scales for vertical and horizontal visual angles of 5°–30° were constructed with the method of angle production and were compared with scales for orientation in the frontal plane. In Experiment 3, vertical and horizontal visual angles of 3°-80° were judged with the method of verbal estimation. The main results of the experiments were as follows: (1) The obtained angles for visual angle are described by a quadratic equation, θ′=a+bθ+cθ² (where θ is the visual angle; θ′, the obtained angle;a, b, andc, constants). (2) The linear coefficientb is larger than unity and is steeper for vertical direction than for horizontal direction. (3) The quadratic coefficientc is generally smaller than zero and is negatively larger for vertical direction than for horizontal direction. And (4) the obtained angle for visual angle is larger than that for orientation. From these results, it was possible to predict the horizontal-vertical illusion, over-constancy of size, and the moon illusion.     

Affective stimulus properties influence size perception and the Ebbinghaus illusion

In the New Look literature of the 1950s, it has been suggested that size judgments are dependent on the affective content of stimuli. This suggestion, however, has been 'discredited' due to contradictory findings and methodological problems. In the present study, we revisited this forgotten issue in two experiments. The first experiment investigated the influence of affective content on size perception by examining judgments of the size of target circles with and without affectively loaded (i.e., positive, neutral, and negative) pictures. Circles with a picture were estimated to be smaller than circles without a picture, and circles with a negative picture were estimated to be larger than circles with a positive or a neutral picture confirming the suggestion from the 1950s that size perception is influenced by affective content, an effect notably confined to negatively loaded stimuli. In a second experiment, we examined whether affective content influenced the Ebbinghaus illusion. Participants judged the size of a target circle whereby target and flanker circles differed in affective loading. The results replicated the first experiment. Additionally, the Ebbinghaus illusion was shown to be weakest for a negatively loaded target with positively loaded and blank flankers. A plausible explanation for both sets of experimental findings is that negatively loaded stimuli are more attention demanding than positively loaded or neutral stimuli.