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PubMed1990

Differential use of distance and location information for spatial localization.

Five experiments are reported in which subjects judged the movement or spatial location of a visible object that underwent a combination of real and induced (illusory) motion. When subjects attempted to reproduce the distance that the object moved by moving their unseen hands, they were more affected by the illusion than when they pointed to the object's perceived final location. Furthermore, pointing to the final location was more affected by the illusion when the hand movement began from the same position as that at which the object initially appeared, as compared with responses that began from other positions. The results suggest that people may separately encode two distinct types of spatial information: (1) information about the distance moved by an object and (2) information about the absolute spatial location of the object. Information about distance is more susceptible to the influence of an induced motion illusion, and people appear to rely differentially on the different types of spatial information, depending on features of the pointing response. The results have important implications for the mechanisms that underlie spatially oriented behavior in general.

Adult↗
PubMed1991

Determinants of spatial priming in environmental memory.

Spatial priming in recognizing objects in experimentally learned environments has been proposed as strong evidence for spatial organization of environmental memory. However, in all studies showing recognition priming effects, encoding and rehearsal contiguity may have coincided with spatial proximity, and thus priming may have been due to temporal associations formed during rehearsal, not encoded spatial relations per se. We investigated this question in four experiments, using a trip trial learning method in which temporal contiguity and spatial relations were independent. In Experiment 1, no spatial priming in recognition was found, even though indirect evidence suggested that subjects had encoded spatial relations. In Experiment 2, the trip trial method was compared with the free study procedure commonly used in previous priming studies. Spatial priming occurred only for free study subjects, even though the two groups were equivalent on direct measures of encoding accuracy. In Experiment 3, spatial priming in recognition was obtained with a modification of the trip trial method in which temporal and spatial contiguity were deliberately confounded. In Experiment 4, the unmodified trip trial method produced spatial priming in a location-decision task. Taken together, our results suggest that environmental memory may be spatially organized, but retrieval of object identities does not necessarily activate encoded spatial relations.

Adult↗
PubMed1999

Spatial knowledge acquisition from maps and from navigation in real and virtual environments.

In this study, the nature of the spatial representations of an environment acquired from maps, navigation, and virtual environments (VEs) was assessed. Participants first learned the layout of a simple desktop VE and then were tested in that environment. Then, participants learned two floors of a complex building in one of three learning conditions: from a map, from direct experience, or by traversing through a virtual rendition of the building. VE learners showed the poorest learning of the complex environment overall, and the results suggest that VE learners are particularly susceptible to disorientation after rotation. However, all the conditions showed similar levels of performance in learning the layout of landmarks on a single floor. Consistent with previous research, an alignment effect was present for map learners, suggesting that they had formed an orientation-specific representation of the environment. VE learners also showed a preferred orientation, as defined by their initial orientation when learning the environment. Learning the initial simple VE was highly predictive of learning a real environment, suggesting that similar cognitive mechanisms are involved in the two learning situations.

Adolescent↗
PubMed1990

Pervasiveness and magnitude of context effects: evidence for the relativity of absolute magnitude estimation.

To test the assertion that absolute magnitude estimation serves to minimize context effects, two experiments were conducted in which area stimuli were judged under differing conditions. In Experiment 1, four groups of subjects made magnitude estimations of triangles ranging in area from 1.5 to 3,072 cm2. No standard or modulus was used, and instructions were similar to those used in absolute magnitude estimation experiments. Each group first judged a different subrange of the stimuli (1.5-24; 48-768; 6-96; or 192-3,072 cm2) before making judgments of the remaining stimuli. In Experiment 2, two groups of subjects made magnitude estimations of triangles ranging in area from 1.5 to 12,288 cm2, with each group first judging a different subrange of stimuli (1.5-24 cm2 or 768-12,288 cm2). The design and instructions were virtually identical to those used in absolute magnitude estimation experiments. Our results indicate that the wording of the instructions is not crucial and that judgments are influenced in two ways that are not predicted by proponents of absolute magnitude estimation. First, the power functions fit to the initially presented subranges (e.g., 1.5-24 cm2), which were judged without contextual effects produced by previously presented stimuli, were inconsistent with one another. Second, judgments of the remaining stimuli were influenced by the subrange of stimuli judged initially. The prevalence of context effects in both experiments, in spite of instructional differences, suggests that although one should avoid using a standard and modulus, there is little else to be gained by adopting the absolute magnitude estimation procedure.

Adult↗
PubMed1990

Detection and discrimination of coherent motion.

When viewing a pair of bars defined by the difference of spatial Gaussian functions (DOGs), human observers can discriminate accurately the relative movements of the bars, even when they differ in spatial frequency. On each trial, observers viewed two brief presentation intervals in which a pair of vertically oriented DOGs moved randomly back and forth within a restricted range. During one interval, both bars moved in the same horizontal direction and by the same magnitude (correlated movements); in the other interval, their movements were uncorrelated. When discrimination accuracy is related to the simultaneous detection of two independent movements, it was found that, if observers can detect the movements of spatially separated bars, they can tell whether their relative movements are correlated. Performance remained remarkably accurate even when the two bars differed in spatial frequency by more than two octaves or were presented separately to the two eyes. Apparently, the accurate discrimination of coherent motion involves an efficient spatial integration of optical motion information over multiple spatial locations and multiple spatial scales.

Adult↗
PubMed1991

Calibration of retinal image size with distance in the Mongolian gerbil: rapid adjustment of calibrations in different contexts.

Mongolian gerbils were trained to jump from one platform to another across a gap whose size varied randomly from trial to trial. In test sessions, probe landing platforms differing in width from those used in training were used, and the distance that the animals jumped was measured. The first experiment demonstrated that the gerbils learned to calibrate the retinal image size of the landing platform with its distance and that they could learn more than one calibration at a time. The second experiment provided evidence that such calibrations are rapidly adjusted to environmental contingencies. These findings suggest that retinal image size might be a useful distance cue for gerbils in a variety of ecological contexts.

Animals↗
PubMed1992

The word-superiority effect does not require a T-scope.

Six experiments examined the possibility of obtaining a word-superiority effect (WSE) without the use of brief stimulus exposures or a poststimulus mask. In each experiment, subjects were presented a stimulus string and two alternative strings that differed by a single letter (Reicher, 1969). The alternatives and stimulus remained in view until subjects responded, and subjects were under no pressure to respond quickly. In Experiments 1-3, the stimuli were presented in very small type so that they were difficult to see. Subjects were significantly more accurate with words than with nonwords, letters embedded among digits, or letters embedded among number signs (#s). In Experiments 4 and 5, the stimuli were embedded in a simultaneously present pattern mask. Subjects were significantly more accurate with words than with single letters by themselves. In the final experiment, the stimuli were presented in a mask with specific spatial frequency characteristics, and performance was significantly better with words than with nonwords. The WSE is a more general phenomenon than previously supposed; it is not limited to a tachistoscopic exposure.

Adult↗
PubMed1992

Haptic probing: perceiving the length of a probe and the distance of a surface probed.

Knowing about the properties of objects by wielding them and knowing about the distances of surfaces by striking them with objects as probes are examples of dynamic or effortful touch. Six experiments focused on the invariant mechanical parameters that couple the time-varying states (displacements, velocities) of hand-held rods to the time-varying torques and forces imposed upon them by wielding and probing. There were three major conclusions. First, when a probe is wielded without contact, perceived probe length is a function of the probe's rotational inertia; however, with contact, perceived probe length is affected by the rotational inertia and the distance of the point of contact from the probe's center of percussion. Second, when a surface is struck with a probe, perceived surface distance is affected by the probe's rotational inertia and the angle of inclination of the probe at contact. Third, under seemingly identical conditions of probing, either probe length or surface distance can be perceived selectively without confusion. Results were discussed in terms of haptic information, haptic attention, and the dynamics of probing.

Adult↗
PubMed1992

The interaction of perceived distance with the perceived direction of visual motion during movements of the eyes and the head.

A horizontally moving target was followed by rotation of the eyes alone or by a lateral movement of the head. These movements resulted in the retinal displacement of a vertically moving target from its perceived path, the amplitude of which was determined by the phase and amplitude of the object motion and of the eye or head movements. In two experiments, we tested the prediction from our model of spatial motion (Swanston, Wade, & Day, 1987) that perceived distance interacts with compensation for head movements, but not with compensation for eye movements with respect to a stationary head. In both experiments, when the vertically moving target was seen at a distance different from its physical distance, its perceived path was displaced relative to that seen when there was no error in perceived distance, or when it was pursued by eye movements alone. In a third experiment, simultaneous measurements of eye and head position during lateral head movements showed that errors in fixation were not sufficient to require modification of the retinal paths determined by the geometry of the observation conditions in Experiments 1 and 2.

Adult↗
PubMed1993

Effects of good form and spatial frequency on global precedence.

Does the global precedence effect depend on the goodness of the global form and low spatial frequencies? In Experiments 1 and 2, under a variety of attentional and task conditions, a global advantage in response time (RT) occurred in "good," many-element compound patterns but not in "poor," few-element patterns (unless the local elements were too small to be easily recognized). Symmetric interference effects were found in all patterns, however, suggesting that global and local information were encoded in parallel and that the global advantage in RT involved some postperceptual processes. Experiments 3A and 3B showed that the global advantage in RT and perceived pattern goodness depend on low spatial frequencies: Lowpass-filtered patterns rated as "good" showed the usual global advantage in RT, but highpass-filtered, many-element forms rated as "poor" did not. These findings suggest that a global advantage in RT requires an unambiguous global form conveyed by low spatial frequencies.

Adult↗
PubMed1993

The logic of misperceived distance (or location) theories of the Poggendorff illusion.

For the Poggendorff display (transversal interrupted by parallel lines), the typical distance-misperception theory postulates that a particular linear distance extending across the empty space between parallels is underestimated; examples are the intertransversal slant distance defined by the closest ends of the transversal segments (a "wings-in Müller-Lyer like" underestimation) or the perpendicular distance between parallels (parallels "attract"). Distance misperception by itself, however, can neither establish that perceived transversal misalignment exists for a Poggendorff display nor specify the perceived-location condition(s) that will produce perceptual collinearity. The perceptual displacement vector is introduced as a means of specifying fully the perceptual mislocation (displacement) of one transversal segment with respect to the other. Given this vector information (direction as well as distance), the logical soundness of theories postulating distance or location misperception were evaluated, and they were compared on the basis of extant data. Such vector information can be used to evaluate other classes of theories as well.

Distance Perception↗
PubMed1993

Visual angle as a determinant of perceived interobject distance.

Two new experiments and a reanalysis of Toye's (1986) data are used to examine the relationship between true distance and perceived distance in natural scenes. In the first experiment, 8 subjects estimated 78 interobject distances, formed by all pairs of 13 objects, while viewing the objects from a fixed position. The results showed that estimated distance is a linear function of the visual angle between objects as well as of the true distance. This relationship results in distances perpendicular to the line of sight being overestimated in relation to true distances and to distances parallel to the line of sight. These findings were confirmed by reanalysis of a comparable data set from Toye. Since changes in the visual angle can come about through changes in alignment with the line of sight, viewing distance, or interobject distance, Experiment 2 was designed to determine whether the visual angle effect was due to one of these, or whether it was an independent effect. In Experiment 2, 8 subjects estimated six interobject distances from 12 viewing positions. The results showed that visual angle predicted estimated distance independently of how the change in visual angle came about, suggesting that the greater the visual angle between objects, the more their separation is overestimated.

Adult↗
PubMed1993

Perceiving the size of trees: biological form and the horizon ratio.

Physical constraints produce variations in the shapes of biological objects that correspond to their sizes. Bingham (in press-b) showed that two properties of tree form could be used to evaluate the height of trees. Observers judged simulated tree silhouettes of constant image size appearing on a ground texture gradient with a horizon. According to the horizon ratio hypothesis, the horizon can be used to judge object size because it intersects the image of an object at eye height. The present study was an investigation of whether the locus of the horizon might account for Bingham's previous results. Tree images were projected to a simulated eye height that was twice that used previously. Judgments were not halved, as predicted by the horizon ratio hypothesis. Next, the original results were replicated in viewing conditions that encouraged the use of the horizon ratio by including correct eye height, gaze level, and visual angles. The heights of cylinders were inaccurately judged when they appeared with horizon but without trees. Judgments were much more accurate when the cylinders also appeared in the context of trees.

Adult↗
PubMed1995

Magnitude of luminance modulation specifies amplitude of perceived movement.

A compelling impression of movement, which is perceptually indistinguishable from a real displacement, can be elicited by patterns containing no spatially displaced elements. An apparent oscillation, w-movement, was generated by a stationary pattern containing a large number of horizontal pairs of spatially adjacent dots modulated in brightness. The observer's task was to adjust the perceived amplitude of the w-motion to match the amplitude of a real oscillation. All of the data can be accounted for by a simple rule: If the relative change in the luminance, W = delta L/L, between two adjacent stationary dots is kept constant, the distance over which these dots appeared to travel in space comprises a fixed fraction of the total distance by which they are separated. The apparent amplitude of the w-motion increases strictly in proportion with luminance contrast, provided that the contrast is represented in the motion-encoding system by a rapidly saturating compressive Weibull transformation. These findings can be explained in terms of bilocal motion encoders comparing two luminance modulations occurring at two different locations.

Attention↗
PubMed1997

Time-distance relations in shifting attention between locations on one's body.

Does the time to discriminate the presence or absence of a tactile stimulus depend on its distance from the bodily location to which one has been attending? Subjects were tested by the presentation of air puffs at four of eight possible locations on the body. In each trial of Experiment 1, (1) subjects attended auditorily to an announcement of one of the eight locations; (2) 2 sec later, a second location was announced and, simultaneously, air puffs were presented at a randomly selected four of the eight locations; (3) the subjects reported as quickly as possible on whether or not air puffs had been presented at the second-announced location. Overall, reaction times increased with the distance between the just-attended and the tested locations. Experiment 2 was undertaken to determine whether the operative distance was distance through the subject's body or directly through three-dimensional space. The subjects were tested as in Experiment 1, but with their arms and legs either side-by-side in front or spread out to each side. Reaction times then depended more on straight-line distance in space than on distance through the body.

Adult↗
PubMed1997

Visually perceived location is an invariant in the control of action.

We provide experimental evidence that perceived location is an invariant in the control of action, by showing that different actions are directed toward a single visually specified location in space (corresponding to the putative perceived location) and that this single location, although specified by a fixed physical target, varies with the availability of information about the distance of that target. Observers in two conditions varying in the availability of egocentric distance cues viewed targets at 1.5, 3.1, or 6.0 m and then attempted to walk to the target with eyes closed using one of three paths; the path was not specified until after vision was occluded. The observers stopped at about the same location regardless of the path taken, providing evidence that action was being controlled by some invariant, ostensibly visually perceived location. That it was indeed perceived location was indicated by the manipulation of information about target distance--the trajectories in the full-cues condition converged near the physical target locations, whereas those in the reduced-cues condition converged at locations consistent with the usual perceptual errors found when distance cues are impoverished.

Adult↗
PubMed1995

Resource scarcity and outcome conflict in time-sharing performance.

The efficacy of the resource-scarcity and outcome-conflict views in explaining dual-task interference was examined. A discrete-continuous task pair was purposely chosen to allow fine-grained analysis of time-shared performance. The relative priority of the dual task was manipulated by a secondary task technique to test for performance tradeoff that would be indicative of resource allocation. The temporal predictability of the discrete stimuli was manipulated to examine possible strategic avoidance of interference. The moment-by-moment data did not reveal any evidence for a switching strategy. It was concluded that the intricate interference patterns could be more easily interpreted within the resource framework than within the outcome-conflict framework.

Adolescent↗