The anchoring of lightness perception was tested in simple visual fields composed of only two regions by placing observes inside opaque acrylic hemispheres. Both side-by-side and center/surround configurations were tested. The results, which undermine Gilchrist and Bonato's (1995) recent claim that surrounds tend to appear white, indicate that anchoring involves ...

The present study investigates the dynamics of changes in interpretation of ambiguous sentences. The sentences used had alternative interpretations with different surface structures (bracketing). Continua were created by systematic manipulation of prosodic cues (relative foot duration), resulting in stimulus sentences that spanned the range between the two interpretations. Continua were ...

We describe sound stimuli that produce the perception of complete rotation around the head. Such stimuli are analogous to wide-field motion stimuli used in visual research, though auditory stimuli, unlike visual stimuli, can be perceived at any point around the head; they are the only cues for spatial perception behind ...

We have applied a multiple scale, 2-D model of brightness perception to a broad range of brightness phenomena. The filters encapsulate only processing that is well established to occur in retinal ganglion cells. Their outputs are then combined in the simplest way compatible with the earliest levels of cortical processing. ...

Perception should change if an error in perception is detected. Yet how can information that comes through the senses ever indicate that those very senses aren't accurate? Knowledge of objects that arises independently of sensory experience can be used to check the sensory information for errors. For instance, an a ...

Three compelling luminance-gradient effects are described. The first effect concerns a brightness enhancement and a luminous mist spreading out from a central area having the same luminance as the white background and surrounded by four rectangular inducers shaded with a linear luminance gradient. The second effect is perceived with a ...

In the 1920s Max Wertheimer enunciated a credo of Gestalt theory: the properties of any of the parts are governed by the structural laws of the whole. Intense efforts at the time to discover these laws had only very limited success. Psychology was in the grips of the Fechnerian tradition ...

A large variety of neurosensory testing modalities have been used to evaluate skin sensitivity of the lower lip and chin after sagittal split osteotomy of the mandible. In this study we compared purely clinical impressions of the sensitivity of the lower lip and chin with objective assessments of it. The ...

It has been argued that neglect of contralateral stimuli following brain damage might be associated with either a compressed or an anisometric neural representation of space along the earth-horizontal axis. Two different models have been put forward. One model proposes a uniform compression of subjective space, while the other envisages ...

Four experiments demonstrate that lines indicating path of movement can generate rotational percepts in a multistable motion display that usually produces only horizontal or vertical motion percepts. The properties of the path-of-movement lines are predicted by a neural-network theory of visual perception. Experimental results validate the theory's predictions by demonstrating ...

Vibrotactile prostheses for deaf or blind persons have been applied to any number of different locations on the body, including the finger, wrist, forearm, abdomen, back, and nape of the neck. The discriminability of patterns presented by such devices can be affected by the acuity of the site of application ...

Five experiments addressed the perception of curvilinear heading under various conditions of optical flow. Perception of heading was unaffected by optical noise (Experiment 1) and was successful and equally accurate for flows generated by circular and elliptical paths of locomotion (Experiment 2). In Experiment 3, random perturbations of vector magnitudes ...

Two different models have argued that neglect of contralateral stimuli following brain damage might be associated with either a compressed or an anisometric neural representation of space along the earth-horizontal axis. We tested these models by determining neglect patients' perception of spatial distances in the horizontal plane. We found no ...

We examined the effect of body posture upon visually induced perception of self-motion (vection) with various angles of observer's tilt. The experiment indicated that the tilted body of observer could enhance perceived strength of vertical vection, while there was no effect of body tilt on horizontal vection. This result suggests ...

The effects of the size and eccentricity of the visual stimulus upon visually induced perception of self-motion (vection) were examined with various sizes of central and peripheral visual stimulation. Analysis indicated the strength of vection increased linearly with the size of the area in which the moving pattern was presented, ...

While sitting alone in complete darkness, 3 participants who had ingested psychotropic concentrations of lysergic acid diethylamide reported diffuse blobs of white, purplish, or greenish-yellow lights as two horseshoe magnets rotated at 0.5 Hz. The experiences were not reported when the magnets were stationary or removed from the apparatus. The ...

In this investigation of monocular perception of egocentric distance, the authors advocate the necessity of a perception-action approach because calibration is intrinsic to definite distance perception. A helmet-mounted camera and display were used to isolate optic flow generated by participants' head movements toward a target, and participants' reaches to place ...

1. We have recently shown that perception of intestinal stimuli increases by spatial summation phenomena. Our aim was to determine in humans whether intestinal perception depends on (a) the length of gut stimulated, and (b) the distance between stimuli. 2. In a first series of studies, we compared perception of ...

Sequential changes in small separated texture elements can produce perception of a moving form with continuous boundaries. This process of spatiotemporal boundary formation may exist to provide a robust means of detecting moving objects that occlude more distant textured surfaces. Whereas most research on spatiotemporal boundary formation has been focused ...

Identical visual targets moving across each other with equal and constant speed can be perceived either to bounce off or to stream through each other. This bistable motion perception has been studied mostly in the context of motion integration. Since the perception of most ambiguous motion is affected by attention, ...

The 'direct-perception' model of heading perception posits that heading is computed directly from optic flow without an intervening structural representation of environmental layout. Here, I give an example in which such a representation is seen to play a role in the interpretation of optic flow. Manipulating the outline of concave ...

When observers are presented directionally ambiguous motion, they exhibit a bias for experiencing movement in the direction in which shapes appear to face. We examined the influence of rigidity of a shape on the forward-facing bias with stimuli whose directionality is biologically specified. In general, the lack of shape correspondence ...

Tactile pattern recognition depends on form and texture perception. A principal dimension of texture perception is roughness, the neural coding of which was the focus of this study. Previous studies have shown that perceived roughness is not based on neural activity in the Pacinian or cutaneous slowly adapting type II ...

Kimchi (Kimchi, R., 1992. Primacy of wholistic processing and global/local paradigm: A critical review. Psychological Bulletin 112, 24-38) proposed that the perception of hierarchical stimuli is dependent on the number of local elements. The local level of stimuli with smaller numbers of elements is perceived as discrete forms, and irrelevant ...

PURPOSE: To investigate the characteristics of interaction between color and motion perception in primary open angle glaucoma (POAG) and measure motion perception of B, G and R cones, thus find a more sensitive method to diagnose the visual nerve damage in POAG. METHODS: Motion perceptions of B, G and R ...

This paper presents several approaches to the machine perception of motion and discusses the role and levels of knowledge in each. In particular, different techniques of motion understanding as focusing on one of movement, activity or action are described. Movements are the most atomic primitives, requiring no contextual or sequence ...

This work provides theoretical and empirical arguments in favor of an approach to phonetics that is called double-weak. It is so called because it assumes relatively weak constraints both on the articulatory gestures and on the auditory patterns that map phonological elements. This approach views speech production and perception as ...

A pilot's perception of variables presented on the Electronic Flight Instrument System, EFIS, was investigated. A stimulus response technique was used to determine the accuracy and speed of the perception process. By varying the exposure time of the stimuli, it is shown that the perception of a variable's magnitude is ...

I investigated the discrimination of rigid from nonrigid structure and the perception of affine stretches along the line of sight [Norman & Todd (1993). Perception and Psychophysics, 53, pp. 279-291]. Investigations of performance at discriminating rigid from nonrigid structure showed that performance improved when number of views and amount of ...

Laparoscopy is a telepresence task since the surgeon has no direct contract with the patient. Performance of the surgeon will increase if his sense of telepresence is improved. This can be achieved by restoring the hampered action perception coupling. With respect to visual perception this means that the surgeon should ...

BACKGROUND: In this study, we tested the hypothesis that low smooth pursuit gain in schizophrenia is related to an abnormality in motion perception. METHODS: The subjects were 19 schizophrenics treated with clozapine and 19 controls. In addition to smooth pursuit and motion perception paradigms, sustained attention was also assessed using ...

The phenomenon of stroboscopic alternative motion exhibits five different percepts that are seen with an increase in the frequency of presentation: (a) succession, (b) fluttering motion, (c) reversible clockwise and counter-clockwise turning motion, (d) oppositional motion and (e) simultaneity. From a synergetic point of view the increase in frequency is ...

Twenty subjects with burning mouth syndrome (BMS) and 20 control subjects were tested for oral size perception. Blindfolded subjects assessed the size of holes (2.38-12.70 mm diameter) presented to the tongue, using their fingers to select a matching hole from a comparator series of 31 holes (0.76-15.87 mm diameter) using ...

Experiments in which a single target pattern is discriminated from multiple background distractors show that certain shaded, two-dimensional (2-D) stimuli consistent with a top-lit, polyhedral interpretation can be processed fast (< 80 msec) and in parallel. Unshaded line drawings of the same shapes, however, are processed serially. Strong pop-out asymmetries ...

To explore the extent to which functional systems within the human posterior parietal cortex and the superior temporal sulcus are involved in the perception of action, we measured cerebral metabolic activity in human subjects by positron emission tomography during the perception of simulations of biological motion with point-light displays. The ...

Moving and acting in a 3D environment requires the perception of its 3D structure. Vision is known to play a crucial role in the control of self-motion, particularly through the changes in the retinal image subsequent to movements of the observer. Reciprocally, signals related to self-motion can also influence our ...

Duplex perception occurs when part of the acoustic signal is used for both a speech and a nonspeech percept. This phenomenon has been interpreted as evidence of a distinct system for speech perception that precedes other specialized systems of general auditory processing (such as auditory grouping, and perception of pitch, ...

Thresholds for the perception of linear vection were measured. These thresholds allowed us to define the spatiotemporal contrast surface sensitivity and the spatiotemporal domain of the perception of rectilinear vection (a visually induced self-motion in a straight line). Moreover, a Weber's law was found, such that a mean relative differential ...

Two experiments investigated observers' perception of 3-D structure when optical sources of information were contradictory. When motion and stereoscopic disparities specified different surfaces, the perceptual outcome dependent strongly on the direction of curvature present within each modality. Previous research has shown that the perception of surface slant and curvature is ...

The perception of ego-velocity (PEV) during sinusoidal linear acceleration (otolith stimulation) is investigated with a psychophysical method proposed by Wertheim (1990;1). This method is based on the threshold for object motion perception measured during ego-motion. In a first experiment, PEV was measured both with and without illumination of the experimental ...

The defective parts of the visual field of two brain-injured patients were stimulated with different spots of light. There is evidence for at least five independent visual functions which can be restored due to constant stimulation of the blind part of the visual field: (1) The constant stimulation of the ...

Direct-phi perception elicited by a reverse-phi (i.e. reversed-polarity) stimulus may well be accounted for, if the front-end filters of a classical Reichardt unit are full-wave rectifiers. It is shown that reverse-phi perception is progressively replaced by direct-phi perception when either the spatial or the temporal modulation of the reversed-polarity stimuli ...

Two experiments were directed at the comparison between two perspectives on the perception of size achieved by probing the gap between two occluded distal surfaces by means of a hand-held rod. One perspective was the classical size-distance invariance hypothesis developed for the problem of visual size perception with a central ...

The vestibular sensors are the necessary source of information for estimating self-displacement during passive linear transport. Displacement has to be computed from the otolith signal by means of an integration process (path integration), which provides a measure of linear acceleration. However, the onset of self-motion perception is delayed due to ...

Two experiments were conducted to examine the effect of changes in the sign of element contrast on perceptions of the Ternus apparent motion display. In the first experiment, the contrast polarity of all three elements in the display were alternated from the first frame of view to the second. At ...

To better understand the damage to the motion pathway that occurs in senile dementia of the Alzheimer type (SDAT), we developed a system to assess separately the conscious perception and unconscious detection of motion in patients with SDAT. Motion perception thresholds were significantly elevated in SDAT (n = 9) compared ...

Although major firms do not publish their pricing and packaging strategies, an analysis of 83 pairs of boxes of breakfast cereals using Stevens' Law showed that firms price their products on the perception of size rather than by actual size. By contrast, laundry detergents are priced by actual weight and ...

Gibson's 1954 article is paradoxical: This forward-looking review of visual motion perception anticipates developments in the field, yet those developments were achieved without closely following Gibson's footsteps. This commentary offers several possible reasons for the dormancy of Gibson's ideas about motion perception and evaluates contemporary work on motion perception in ...

In a recent paper, Lappin and Love (1992) showed that depth judgments, based on planar motion of a stimulus, are remarkably precise. This led them to the conclusion that perception of planar motion allows acquiring metric information about visual space. We show, however, that Lappin and Love's stimuli contained 2-D ...

Although interest in the phenomenon of visual occlusion is of very long standing, only a small number of experimental studies have been reported, and available theories fail to give satisfactory explanations of the data. In this paper the efficacy of local factors in organising the perception of globally regular occlusion ...