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PubMed1979

Stimulus information and sequential dependencies in magnitude estimation and cross-modality matching.

Descriptive models of magnitude estimation and cross-modality matching derived from two different approaches to psychophysical judgment, the response ratio hypothesis and the fuzzy judgment approach, are compared. The two approaches emphasize different bodies of facts but both attempt to account for sequential dependencies in psychophysical judgments. Both models suggest a hierarchical multiple linear regression model for such data. Some of the predictions of the models are explored in the context of two experiments in which the amount of stimulus information available to subjects in magnitude estimation and cross-modality matching tasks is varied. The fuzzy judgment approach generally does better in explaining the form of such data.

Adolescent↗
PubMed1980

Confirmed reservations: mental travel.

When Kosslyn, Ball, and Reiser asked subjects to scan a memorized picture, they found a strong positive linear relationship between distance scanned and reaction time. However, more recent research has suggested that this result may be as much a function of the demand characteristics of the experiment as a reflection of any structural properties of the image. To further test this possibility with complex stimuli, college subjects were either presented with Kosslyn's pictorial stimuli or verbal descriptions of same in a "nonexperiment" and were asked to predict their scanning times. The subjects were able to produce high linear correlations between scanning distance and predicted scanning time. This result is consistent with a demand characteristics explanation of the correlation between distance and reaction time that is obtained in actual image-scanning studies.

Distance Perception↗
PubMed1980

Principles of perceptual organization and spatial distortion: the gestalt illusions.

In five interleaved experiments, conducted with 94 observers, it is shown that organization of the visual field according to gestalt principles results in measurable spatial distortions. Using the principles of proximity, similarity, good continuation, and two types of closure, it was found that interior distances (within a perceptual unit or group) are underestimated relative to exterior distances. The relationship between these spatial distortions and the resultant perceptual organization are discussed.

Distance Perception↗
PubMed1981

Effects of a secondary task on the accuracy of single aiming movements.

Recently, Schmidt, Zelaznik, and Frank and Schmidt, Zelaznik, Hawkins, Frank, and Quinn have demonstrated that in rapid, single aiming movements, variability in the movement's kinetic requirements resulted in variability in the movement's amplitude. This new explanation of the speed-accuracy trade-off in motor control, however, does not predict or explain inaccuracy for slower movements (greater than 200 msec). In the two experiments reported, we demonstrate that the Schmidt et al. model can predict variability in slow aiming movements if attention is occupied with an additional task. Subjects were required to perform single aiming movements in either 500 (Experiment 1) or 200 (Experiment 2) msec. In both experiments, the movement amplitude (30, 45, 60, and 75 cm in Experiment 1, and 10, 20, and 30 cm in Experiment 2) and the probability of an auditory probe-reaction time (RT) task were manipulated. Results indicated that only when the movement time (MT) was 500 msec did the probe-RT task change the relationship between the effective target width and the movement's average velocity. This result extended the scope of the Schmidt et al. model to movements with a duration greater than 200 msec. In addition, it seems as though slow movements are controlled by attention-demanding mental processes.

Attention↗
PubMed1982

Saccadic eye movements to peripherally discriminated visual targets.

Two experiments required subjects to identify a peripheral target embedded among nontarget stimuli and fixate it as quickly as possible with a single saccadic eye movement. Experiment 1 varied both the target distance and its angular position between trials; the mean oculomotor latency, the proportion of erroneous movements, and the proportion of (correct) movements followed by a corrective saccade all increased as a function of target distance. Experiment 2 held target distance constant (12.7 degrees) and used verbal instructions to manipulate the speed and accuracy of the subject's oculomotor performance between conditions. The speed/accuracy trade-off was similar for all subjects. The reduced uncertainty about target distance in Experiment 2 made each subject's oculomotor performance more efficient. Error trials not only included apparent perceptual errors (initial movements to nontarget stimuli) but also motor errors - that is, instances when the initial erroneous movement was followed, with an extremely short latency, by a large saccade to the target. The characteristics of these motor errors suggest that the saccade is not planned in terms of its amplitude and direction in retinal coordinates.

Adult↗
PubMed1983

Is continuous visual monitoring necessary in visually guided locomotion?

Subjects were asked to walk to targets that were up to 21 m away, either with vision excluded during walking or under normal visual control. Over the entire range, subjects were accurate whether or not vision was available as long as no more than approximately 8 sec elapsed between closing the eyes and reaching the target. If more than 8 sec elapsed, (a) this had no influence on distances up to 5 m, but (b) distances between 6-21 m were severely impaired. The results are interpreted to mean that two mechanisms are involved in guidance. Up to 5 m, motor programs of relatively long duration can be formulated and used to control activity. Over greater distances, subjects internalized information about the environment in a more general form, independently of any particular set of motor instructions, and used this to control activity and formulate new motor programs. Experiments in support of this interpretation are presented.

Adult↗
PubMed1982

Density versus feature weights as predictors of visual identifications: comment on Appelman and Mayzner.

Appleman and Mayzner's application of the distance-density model to confusion data is compared with Keren and Baggen's application of the feature-matching model. In both applications, the distinctive features of two stimuli are predictors of the number of confusion errors. However, the models differ in that the feature-matching model assigns weights to the features and assumes that the shared feature weights also affect the probability of confusion. In contrast, the distance-density model assumes that the number of confusions between two stimuli is affected by the number of stimuli in the entire stimulus set that are similar to the two stimuli (density). The two models are compared in the context of a set of digit identification data.

Discrimination Learning↗
PubMed1982

Application of geometric models to letter recognition: distance and density.

This article reviews studies in which a single letter is visually presented under adverse conditions and the subject's task is to identify the letter. The typical results for such studies are (a) certain pairs of letters are more often confused than other pairs of letters; (b) certain letters are more easily recognized than others; and (c) confusion errors for a letter pair are often asymmetric, the number of errors differing depending on which letter of the pair is presented as the stimulus. A geometric model incorporating the properties of distance and spatial density (after Krumhansl) is presented to account for these results. The present application of the distance-density model assumes that each letter is constructed in a typical 5 X 7 dot matrix. Each letter is represented in 35-dimensional space based on its constituent dots. A central idea behind the model, embodied in the property of spatial density, is that an explanation of typical results must take into account the relationship of the entire stimulus set to both the presented letter and the responded letter. Specifically, according to the model, (a) pairs of letters that are close in geometric space are more often confused than pairs of letters that are distant; (b) letters that are in less spatially dense regions are more easily recognized than letters that are in more spatially dense regions; and (c) asymmetric confusion errors result when one member of a letter pair is in a denser region than the other member of the letter pair. The distance-density model is applied to published and unpublished results of the authors as well as published results from two other laboratories. Alternative explanations of the three typical letter recognition results are also considered. The most successful alternative explanations are (a) confusions are an increasing function of the number of dots that two letters share; (b) letters constructed from fewer dots are easier to recognize; and (c) asymmetries arise when one member of a letter pair is more easily recognized, since that letter then has fewer confusion errors to give to the other letter of the pair. The model is discussed in terms of the distinction between template matching and feature analysis. An alternative classification of letter recognition models is proposed based on the global versus local qualities of features and the spatial information associated with each feature. The model is extended to explain reaction time study results. It is suggested that the distance-density model can be used to create optimal letter fonts by minimizing interletter confusions and maximizing letter recognizability.

Discrimination Learning↗
PubMed1982

The moon illusion: I. How high is the sky?

The most common explanations of the moon illusion assume that the moon is seen at a specific distance in the sky, which is perceived as a definite surface. A decrease in the apparent distance to the sky with increasing elevation presumably leads to a corresponding decrease in apparent size. In Experiment 1 observers (N = 24) gave magnitude estimates of the distance to the night sky at different elevations. The results did not support the flattened-dome hypothesis. In Experiment 2 observers (N = 20) gave magnitude estimates of the distance to the sky at points around a 360 degrees circle just above the horizon. The results were consistent with those of Experiment 1, and in addition, estimates were highly correlated with the physical distances of buildings at the horizon. In a third, control experiment, observers (N = 20) gave magnitude estimates of the distances of buildings at the horizon. A power function fit the relation between estimated and physical distance (exponent = 1.17) as well as the relation between estimates of the sky points above the buildings (Experiment 2) and estimates of building distances (exponent = .46). Taken together, the results disconfirm all theories that attribute the moon illusion to a "sky illusion" of the sort exemplified by the flattened-dome hypothesis.

Astronomical Phenomena↗
PubMed1984

Terrestrial passage theory of the moon illusion.

Theories of the celestial, or moon, illusion have neglected geometric characteristics of movement along and above the surface of the earth. The illusion occurs because the characteristics of terrestrial passage are attributed to celestial passage. In terrestrial passage, the visual angle subtended by an object changes discriminably as an essentially invariant function of elevation above the horizon. In celestial passage, by contrast, change in visual angle is indiscriminable at all elevations. If a terrestrial object gains altitude, its angular subtense fails to follow the expansion projected for an orbital course: Angular diminution or constancy is equivalent to distancing. On the basis of terrestrial projections, a similar failure of celestial objects in successive elevations is also equivalent to distancing. The illusion occurs because of retinal image constancy, not--as traditionally stated--despite it.

Astronomical Phenomena↗
PubMed1985

Size illusion, distance illusion, and terrestrial passage: comment on reed.

Two assumptions of Reed's (1984) terrestrial passage theory are questioned. First, Reed assumes that the moon's failure to increase in visual subtense while elevating is accounted for strictly by perceptual distancing. This allows a formal account of the moon distance illusion, but at the expense of a compelling explanation of the moon size illusion. Second, in order to explain the distance illusion, Reed assumes that all objects, regardless of their perceived altitude, are perceived to start from a common point at the horizon. Several alternative application of Reed's terrestrial-passage foundation to the actual illusions are suggested.

Astronomical Phenomena↗
PubMed1992

Wayfinding on foot from information in retinal, not optical, flow.

People find their way through cluttered environments with ease and without injury. How do they do it? Two approaches to wayfinding are considered: Differential motion parallax (DMP) is a retinal motion invariant of near and far objects moving against fixation; the information in optical flow (IOF) is a radial pattern of vectors, relying on decomposition of retinal flow. Evidence is presented that DMP guides wayfinding during natural gait, accounting for errors as well as correct responses. Evidence against IOF is also presented, and a space-time aliasing artifact that can contaminate IOF displays is explored. Finally, DMP and IOF are separated, showing they can yield different results in different environments. Thus, it is concluded that (a) DMP and IOF are different, (b) DMP and not IOF is used for wayfinding, (c) moving observers do not usually decompose retinal flow, and (d) optical flow may be a mathematical fiction with no psychological reality.

Adult↗
PubMed1993

Nonvisual navigation by blind and sighted: assessment of path integration ability.

Blindfolded sighted, adventitiously blind, and congenitally blind subjects performed a set of navigation tasks. The more complex tasks involved spatial inference and included retracing a multisegment route in reverse, returning directly to an origin after being led over linear segments, and pointing to targets after locomotion. As a group, subjects responded systematically to route manipulations in the complex tasks, but performance was poor. Patterns of error and response latency are informative about the internal representation used; in particular, they do not support the hypothesis that only a representation of the origin of locomotion is maintained. The slight performance differences between groups varying in visual experience were neither large nor consistent across tasks. Results provide little indication that spatial competence strongly depends on prior visual experience.

Adolescent↗
PubMed1995

Overshadowing in landmark learning: touch-screen studies with pigeons and humans.

Overshadowing in landmark learning was studied in pigeons and undergraduates using a touch-screen spatial search task. Ss searched for an unmarked goal presented in varied locations on a computer screen. Graphic stimuli served as landmarks. The effect of the presence of other landmarks on the control acquired by a given landmark was assessed using a design in which each S was trained with 2 sets of landmarks. Both pigeons (Experiment 1) and humans (Experiments 2-4) showed evidence of learning more about a landmark that was the closest landmark of its set to the goal than about a landmark that was of equal distance to the goal but was not the closest landmark of its set. That is, control by a landmark was overshadowed when it occurred together with a landmark that was closer to the goal. Landmark effectiveness appears to depend not only on the absolute properties of a landmark but on relative factors. The relevance of basic principles of associative learning to spatial landmark learning is discussed.

Adolescent↗
PubMed1984

The mental representation of knowledge acquired from maps.

Recognition priming and distance estimation were used to investigate the mental representation of knowledge acquired from maps. In Experiment 1, recognition priming showed that cities close in route distance primed each other more than cities far in route distance, even when Euclidean distance was equated. Experiment 2 showed that this finding was robust and not an artifact of the way subjects learned the maps. Distance estimations in Experiment 1 supported the priming results. These results indicated that psychological distance in cognitive maps is primarily dependent on route distance rather than Euclidean distance.

Cognition↗
PubMed1987

Application of a cognitive-distance model to learning in a simulated travel task.

A cognitive-distance model for choice, obtained by specializing a general class of models for categorization, was tested in a situation simulating the task of controlling speed of a vehicle in tasks defined by different relations between speed and probability of delay. Subjects exhibited significant learning whenever delay schedules permitted greater-than-chance performance, but on the average they did not approach optimal performance in the sense of choosing speeds so as to maximize distance attained in allowed time. Evidence was obtained that subjects encoded information about probabilities of delay and distributions of distance attained at different speeds quite accurately in memory and that suboptimal performance was due primarily to imperfect discrimination among representations of choice alternatives on a cognitive scale of expected distance.

Adult↗
PubMed1987

Exploring environments by hand or foot: time-based heuristics for encoding distance in movement space.

In Experiment 1, blindfolded observers judged (a) the distance of pathways felt by hand and (b) the straight-line distance between pathway endpoints inferred from such exploration. In Experiment 2, blindfolded observers made corresponding estimates after traversing similar pathways on foot. Pathways were explored under three different speeds. Under both manipulatory and ambulatory exploration, there was substantial length distortion of inferred distance: The straight-line distance was increasingly overestimated with increases in the length of the explored pathway. With manipulatory exploration, slower movements increased length distortion, but duration effects proved secondary to effects of spatial extent. For ambulatory exploration, no duration effects were obtained. Observers used time-independent heuristics, that is, a footstep metric for estimating the pathway actually travelled and a spatial imaging strategy for estimating the inferred line between pathway endpoints. The studies establish length distortion as a general phenomenon in movement space and identify its major causes as spatial rather than temporal.

Adult↗
PubMed1988

Overflow, first-sight, and vanishing point distances in visual imagery.

The relationship between the size of a familiar object and the distances at which it is imaged is examined in three experiments. The distance at which an imaged object overflows the visual field is linearly related to object size, a result consistent with the size-distance invariance hypothesis (Kosslyn, 1980). The distance at which an object is initially imaged, first-sight distance, is related to the object size by a power function with an exponent less than 1. In addition, time required to scan from the first-sight to the overflow distance increases as a function of the difference between the two distance estimates. The distance at which an imaged object becomes too small to be identified, vanishing point distance, is related to object size by a power function with an exponent less than 1. This result does not support predictions made from the size-distance invariance hypothesis or Kosslyn's model of visual imagery. Implications for a theory of visual imagery and memory are discussed.

Adult↗