Judgments of similarity and spatial models

Ss judged the similarity between all pairs of stimulus objects under 3 conditions: when the objects were (a) Munsell 5R color patches varying in value and chroma; (b) parallelorams varying in size and tilt; and (c) circles-with-radius varying in diameter and angle of radius. For each set of judgments, the pattern of deviations from the Euclidean model was used to diagnose the most appropriate spatial model. The results confirm previous findings that the Euclidean space is appropriate for judgments of color patches, but that the city block space is appropriate for judgments of geometrie forms which vary on perceptually distinct dimensions.     

An approach to geometry of visual space with no a priori mapping functions: Multidimensional mapping according to Riemannian metrics

A method of multidimensional mapping is described which constructs a configuration of points {P_i} in a Euclidean map of Riemannian space of constant curvature (hyperbolic, Euclidean, and elliptic) from the dissimilarity matrix (d_ij). The method was applied to the distance matrix in visual space where stimulus points Q_i were either small light points in the dark or small black points in the illuminated field surrounded by white curtains and d_ij represent scaled values of perceptual distances. Configuration of points {Q_i} were at intersections of parallel or distance alleys and horopters for the subject in the horizontal plane of the eye level. In contrast to the theoretical equations for {Q_i} by Luneburg and Blank, no a priori assumption on mapping functions between {Q_i} and {P_i} is necessary in this procedure to fit theoretical curves to {P_i} in the Euclidean map. The data were accounted for better by equations in the hyperbolic plane than by ones in the Euclidean plane. Discussions are made on robustness of Euclidean representation and on how to approach geometry of visual space as a dynamic entity under more natural conditions than the traditional frameless condition for alley and horopter experiments.     

Learning to utilize information presented over two sensory channels

In three separate experiments, Ss were provided with auditory, visual, or simultaneous auditory and visual information in a classification task. Difficulty of classification was manipulated by varying the stimulus exposure duration. Consistent bisensory facilitation effects were noted for later trials, with interference evident on earlier trials. Exposure duration influenced rate and not amount of learning, with bisensory performance being most affected by duration. A transfer paradigm was used in Experiment III, and little if any transfer was noted between unisensory and bisensory stimulus conditions. It was concluded that Ss were extracting the most salient bisensory stimulus components from the auditory and visual modes of information into a unidimensional information configuration.     

A geometrical analysis of the unfolding model: Nondegenerate solutions

Given the complete setR of rank orders derived from some configuration ofn stimulus points inr dimensions in accordance with the unfolding model, a stimulus configuration which generates just these orders will be described as a solution forR. The space is assumed to be Euclidean. Necessary and sufficient conditions are determined for a nondegenerate configuration to be a solution forR. The geometrical conditions which are necessary and sufficient to determine the subset of pairs of opposite orders are also identified and constitute the constraint system for the ordinal vector model.The present work was completed while the writer was in receipt of an Australian Commonwealth Postgraduate Scholarship under the supervision of Professor J. A. Keats.     

Stimules configuration in selective attention tasks

The possibility that perceptual configuration of stimulus elements impairs the ability to attend selectively to individual elements was tested with two-element stimuli, constructed by placing two curved lines in close proximity. Ss rapidly classified series of these stimuli which could differ on both elements or on only one with the second held constant. It was hypothesized that if the two elements formed a configuration, then Ss should have difficulty attending selectively to the element relevant for classification while filtering information from the other element. This result was obtained in one experiment with both stimulus elements oriented vertically, and it is concluded that these stimuli were perceived as unanalyzed, nominally related shapes. In another experiment, with one stimulus element oriented horizontally, selective attention to the relevant element was possible.     

A geometrical analysis of the unfolding model: General solutions

Given the complete setR of rank orders obtained from any configuration ofn stimulus points inr dimensions in accordance with the unfolding model, a configuration from which just these orders may be derived will be described as a solution forR. The space is assumed to be Euclidean. Necessary and sufficient conditions are derived for a configuration to be a solution forR. The geometrical constraints which are necessary and sufficient to determine the subset of pairs of orders and opposites contained inR are also identified and constitute the constraint system for the ordinal vector model. The relationship between the two models is discussed.     

The Simplest Axiom System for Plane Hyperbolic Geometry

We provide a quantifier-free axiom system for plane hyperbolic geometry in a language containing only absolute geometrically meaningful ternary operations (in the sense that they have the same interpretation in Euclidean geometry as well). Each axiom contains at most 4 variables. It is known that there is no axiom system for plane hyperbolic consisting of only prenex 3-variable axioms. Changing one of the axioms, one obtains an axiom system for plane Euclidean geometry, expressed in the same language, all of whose axioms are also at most 4-variable universal sentences. We also provide an axiom system for plane hyperbolic geometry in Tarski's language L _B which might be the simplest possible one in that language.     

Visual recognition memory for complex configurations

Previous studies of recognition memory for heterogeneous pictorial stimuli suggest an unusually large storage and retrieval capacity. In the first experiment, three series of homogeneous pictures (faces, ink blots, snow crystals) were presented to six independent groups of Ss, and recognition was tested immediately or 48 h later. Accuracy and sex were related to stimulus configuration; at both time intervals, accuracy was best for faces and poorest for snow crystals. Levels of accuracy were below those attained in studies using heterogeneous arrays. The results of two other experiments suggest the relative unimportance of verbal mediation in recognition of homogeneous pictorial stimuli.     

Mediating interpersonal expectancies via vocal cues: Differential speech intensity as a means of social influence

Differential vocal emphasis in the tape-recorded instruction reading for a standard person perception task was manipulated by mechanically raising or lowering the volume of the key words describing the success or failure response alternatives on the rating scale. In a series of three experiments, Ss exposed to success emphasis in the instructions rated the stimulus persons as more successful than did Ss exposed to failure emphasis. This trend was reversed for Ss who listened twice to the instructions. None of the Ss reported awareness of the influence attempt.     

Spatial and temporal contributions to the structure of spatial memory.

Three experiments investigated the effects of spatial and temporal contiguity in item recognition, location judgment, and distance estimation tasks. Ss learned the locations of object names in spatial arrays, which were divided into 2 regions. The names of locations were presented during map learning so that critical pairs appeared close in space and close in time, close in space but far in time, far in space but close in time, and far in space and far in time. Names primed each other in recognition only when they were neighbors in both space and time. In contrast, the effects of spatial and temporal contiguity in priming in location judgments were additive. Finally, temporal contiguity affected estimates of Euclidean distance when locations were close together, but not when they were far apart.     

Oculomotor adjustments and size-distance perception

The relationship between perceived size and distance and oculomotor adjustments were assessed in two experiments. In both experiments, Ss were required to make scalar linear size, angular size, and distance judgments of stimuli subtending a constant retinal image size at different levels of convergence. The results of the first experiment indicate that the perceived linear size, angular size, and distance of the stimulus decreased with increased convergence, the decrease in perceived linear size being greater than that of perceived angular size. While again showing a decrease in perceived linear and angular size, the results of the second experiment also show that there was a smaller decrease in perceived distance with increased convergence when Ss continued to view the stimulus as convergence was changed than when they did not view the stimulus as convergence was changed. The implications these results have for size and distance perception are discussed.     

Parallel processing of the attributes of single stimuli

Three experiments are described, in which Ss had to decide whether or not single stimuli, varying along the dimensions of shape and color, satisfied a given criterion. In different conditions, the number of dimensions relevant to the criterion was varied. The first experiment indicates that simple interpretations of a standard Nickerson procedure are potentially artifactual. In the last two experiments, a design involving different difficulties of discrimination was used so that a serial interpretation of the results could be convincingly rejected, even for unpracticed Ss. These results strongly support the view that perceptually parallel processing normally occurs in the identification of single multidimensional stimuli. By this interpretation, apparently similar tasks may produce different patterns of results because of the use of different decision processes by the Ss.     

Confidence ill stimulus predictions and choice reaction time

In two choice reaction time (RT) experiments, a stimulus prediction and a confidence judgment in the prediction preceded each occurrence of one of two stimulus alternatives. Ss identified each stimulus presentation by pressing a left-hand or right-hand telegraph key. In Experiment I the source of the stimulus predictions and confidence estimates was varied between groups of 20 Ss. For each condition, RT to correctly predicted stimuli was an inverse function of prediction confidence. Following incorrectly predicted stimuli, RT was not reliably influenced by confidence when S gave both predictions and confidence judgments; but RT to incorrectly predicted stimuli was an increasing function of confidence when E verbalized the predictions and confidence estimates or when S predicted and E indicated confidence. In Experiment II Ss made predictions and the validity of Es confidence estimate was manipulated between Ss. When Es confidence was perfectly related to the probability of a correct prediction, choice RT to nonpredicted stimuli was inversely related to confidence. However, choice RT to nonpredicted stimuli was not affected by prediction confidence when Es judgments were random.     

Effect of subliminal stimuli on consumer behavior: negative evidence.

The study corrected methodological weaknesses found in previous experiments designed to test the contentions of motivational research theorists that subliminal stimulation can affect buying behavior. The words "Hershey's Chocolate" were presented to a group of 18 experimental Ss below a forced-choice detection threshold. The 19 control Ss had a blank slide superimposed over the same background media. In a highly controlled buying situation neither experimental nor control Ss purchased Hershey's products, but on comparable chocolate products, the experimental Ss bought 5 and the control Ss, 3. A second study tested 15 experimental and 12 control Ss with the stimulus presented just below a recognition threshold. No experimental Ss bought Hershey's; two control Ss did. No support was found for the claims of motivational research theorists.     

Brightness contrast in the cat

Using both the method of paired comparisons and the method of constant stimuli, degree of brightness contrast was determined for two cats. Brightness contrast varied with relative luminance of various parts of the stimulus configuration in a manner comparable to that found in human Ss; brightness constancy was not obtained. The data indicate a fixed, nonadaptive basic visual process rather than a cognitive or adaptive perceptual constancy.     

Axiomatizing geometric constructions

In this survey paper, we present several results linking quantifier-free axiomatizations of various Euclidean and hyperbolic geometries in languages without relation symbols to geometric constructibility theorems. Several fragments of Euclidean and hyperbolic geometries turn out to be naturally occurring only when we ask for the universal theory of the standard plane (Euclidean or hyperbolic), that can be expressed in a certain language containing only operation symbols standing for certain geometric constructions.     

Discussion of a set of points in terms of their mutual distances

Necessary and sufficient conditions are given for a set of numbers to be the mutual distances of a set of real points in Euclidean space, and matrices are found whose ranks determine the dimension of the smallest Euclidean space containing such points. Methods are indicated for determining the configuration of these points, and for approximating to them by points in a space of lower dimensionality.This paper was written in response to suggestions by Harold Gulliksen and by M. W. Richardson. The latter is working on a psychophysical problem in which the dimensionality of a set of points whose mutual distances are available is a central idea.     

Consistency between motor activity and perceived direction of rotation

Three experiments were conducted to test the proposition that engagement in motor activity in a given direction favors the perception of stimulus movement consistent with that direction. Ss simultaneously turned a crank and viewed a stimulus capable of apparent reversal of direction.Experiments 1A and 1B demonstrated that the perceived initial direction of rotation was more stable when it was consistent with the motor activity of the viewer than when it was inconsistent. Experiment 2 demonstrated that when Ss were instructed to perceive a particular direction of rotation for a period of time they tended to engage in motor activity consistent withthatdirection.The results were interpreted as supporting an efference theory of perception.