The joint analysis of direct ratings,pairwise preferences,and dissimilarities

In studies involving judgments of similarity or dissimilarity, a variety of other variables may also be measured. Examples might be direct ratings of the stimuli, pairwise preference judgments, and physical measurements of the stimuli with respect to various properties. In such cases, there are important advantages to joint analyses of the dissimilarity and collateral variables. A variety of models are described for relating these and algorithms described for fitting these to data. A number of hypothesis tests are developed and an example offered.The research reported here was supported by grant number APA 320 to the author by the National Research Council of Canada.     

A technique for the nonmetric analysis of paired comparisons of psychological intervals

A nonmetric coordinate adjustment technique is developed which determines scale values for objects whose interobject intervals (differences in subjective value) have been directly compared. In Monte Carlo simulations, the degree of metric determinancy of the scale values is shown to be quite high even when the amount of error is relatively high. This robustness under high-error conditions permitted the analysis of individual subject data in experiments on the direct comparison of loudness differences and loudness ratios where only one judgment per interval comparison was obtained per subject.This research was supported by a grant from the National Research Council of Canada.     

A stochastic multidimensional scaling procedure for the empirical determination of convex indifference curves for preference/choice analysis

The vast majority of existing multidimensional scaling (MDS) procedures devised for the analysis of paired comparison preference/choice judgments are typically based on either scalar product (i.e., vector) or unfolding (i.e., ideal-point) models. Such methods tend to ignore many of the essential components of microeconomic theory including convex indifference curves, constrained utility maximization, demand functions, et cetera. This paper presents a new stochastic MDS procedure called MICROSCALE that attempts to operationalize many of these traditional microeconomic concepts. First, we briefly review several existing MDS models that operate on paired comparisons data, noting the particular nature of the utility functions implied by each class of models. These utility assumptions are then directly contrasted to those of microeconomic theory. The new maximum likelihood based procedure, MICROSCALE, is presented, as well as the technical details of the estimation procedure. The results of a Monte Carlo analysis investigating the performance of the algorithm as a number of model, data, and error factors are experimentally manipulated are provided. Finally, an illustration in consumer psychology concerning a convenience sample of thirty consumers providing paired comparisons judgments for some fourteen brands of over-the-counter analgesics is discussed.     

Psychophysics without physics: extension of Fechnerian scaling from continuous to discrete and discrete-continuous stimulus spaces

The computation of subjective (Fechnerian) distances from discrimination probabilities involves cumulation of appropriately transformed psychometric increments along smooth arcs (in continuous stimulus spaces) or chains of stimuli (in discrete spaces). In a space where any two stimuli that are each other's points of subjective equality are given identical physical labels, psychometric increments are positive differences ψ(x,y)-ψ(x,x) and ψ(y,x)-ψ(x,x), where x≠y and ψ is the probability of judging two stimuli different. In continuous stimulus spaces the appropriate monotone transformation of these increments (called overall psychometric transformation) is determined uniquely in the vicinity of zero, and its extension to larger values of its argument is immaterial. In discrete stimulus spaces, however, Fechnerian distances critically depend on this extension. We show that if overall psychometric transformation is assumed (A) to be the same for a sufficiently rich class of discrete stimulus spaces, (B) to ensure the validity of the Second Main Theorem of Fechnerian Scaling in this class of spaces, and (C) to agree in the vicinity of zero with one of the possible transformations in continuous spaces, then this transformation can only be identity. This result is generalized to the broad class of “discrete-continuous” stimulus spaces, of which continuous and discrete spaces are proper subclasses.     

The complement of a point subset in a projective space and a Grassmann space

In a projective space we fix some set of points, a horizon, and investigate the complement of that horizon. We prove, under some assumptions on the size of lines, that the ambient projective space, together with its horizon, both can be recovered in that complement. Then we apply this result to show something similar for Grassmann spaces.     

The organization of conspecific face space in nonhuman primates

Humans and chimpanzees demonstrate numerous cognitive specializations for processing faces, but comparative studies with monkeys suggest that these may be the result of recent evolutionary adaptations. The present study utilized the novel approach of face space, a powerful theoretical framework used to understand the representation of face identity in humans, to further explore species differences in face processing. According to the theory, faces are represented by vectors in a multidimensional space, the centre of which is defined by an average face. Each dimension codes features important for describing a face's identity, and vector length codes the feature's distinctiveness. Chimpanzees and rhesus monkeys discriminated male and female conspecifics’ faces, rated by humans for their distinctiveness, using a computerized task. Multidimensional scaling analyses showed that the organization of face space was similar between humans and chimpanzees. Distinctive faces had the longest vectors and were the easiest for chimpanzees to discriminate. In contrast, distinctiveness did not correlate with the performance of rhesus monkeys. The feature dimensions for each species’ face space were visualized and described using morphing techniques. These results confirm species differences in the perceptual representation of conspecific faces, which are discussed within an evolutionary framework.     

Relation of number of different responses to group size and stimulus words in a discrete free-association situation

FlekkØy, K., Holme, I. & Mohn, E. Relation of number of different responses to group size and stimulus words in a discrete free-association situation. Scand. J. Psychol., 1973, 14, 4–8.-An exploration of the total number (D) of different responses given to a stimulus word in a single-word, free-association situation showed that (1) the first 50 Kent-Rosanoff words (in Norwegian) were highly heterogeneous with regard to D; (2) was an asymptotic function of the number of subjects; and (3) the larger D for schizophrenics may be attributed to their higher frequency of individual responses. It was also indicated that D may not be a valid measure of the magnitude of the associative potential of the individual.     

The effects of environmental change on chicks' responses to a familiar stimulus

The purpose of the present experiments was to explore chicks' proximity seeking behaviour in relation to imprinting objects in unfamiliar settings. Experiment I showed that chicks, which were individually imprinted on a stationary imprinting object, displayed reduced proximity seeking behaviour when tested in a pen smaller than the rearing pen. This finding confirmed earlier work on the effects of changed pen size. Experiment II used continuous and intermittent noise rearing and testing conditions, in all possible combinations, and a stationary imprinting object. Increased proximity seeking was found in conditions where the auditory environment was changed from rearing to testing, a result apparently opposite to that obtained in earlier work. It is suggested that the effect of environmental change on proximity seeking may vary with the modality in which change occurs and the salience of the imprinting object.     

Groundhog day: The individual,the couple,the group and the space between

Abstract

The film Groundhog Day first came out in 1993. Five years later, it is still cited in a variety of contexts. The author proposes that this is because the film is a cultural artefact which both elucidates and frustrates the ideal of romantic love in the couple as the agent of internal change.

The author also proposes a re-viewing of the meaning of the concept of couple. The convergence of object relations theories with group analysis suggests that the mind works by repeating and externalizing internal group structures in social relationships. The couple, then, becomes an intermediary structure between the individual and the group where intimacy facilitates a re-working of group internal structures. It is the collapsing and the opening of the ‘space between’ which is the agent of change. This process creates strength, power and a feeling of wholeness. But it also implies the expression of anger, pain and disappointment. The author illustrates these points with an interpretation of the Groundhog Day film and with a clinical case study of a couple in therapy.     

The effect of change in sequential visual stimuli on GSR adaptation: II,the novel stimulus as a disinhibiting stimulus

GSR records were obtained for 20 Ss presented with a series of 80 stimuli (four lights alternating in apparent random sequence). Records were obtained, also, for 20 Ss in each of two groups, using the same procedure: in Group 1, a tone was substituted for one of the lights, early in the sequence, and in Group 2, it was substituted later in the sequence. The tone, the novel stimulus, produced significant changes in the GSR adaptation patterns of the two groups.     

Control of responding by the elements of a compound discriminative stimulus and by the elements as individual discriminative stimuli

In the first of two studies, the responding of four albino rats was differentially reinforced in the presence of noise and light together and then tested in the presence of the noise and the light separately during extinction. The light exercised substantially more control of responding than did the noise. In the second study the responding of a similar group of four rats was differentially reinforced in the presence of the noise and the light separately. Control of responding by the light developed more rapidly than control by the noise. Results suggest that levels of control by stimuli after differential reinforcement with respect to the stimuli together can be predicted by the rates of development of control during differential reinforcement with respect to the stimuli separately.     

The effect of a masked stimulus on the response to the masking stimulus

Four experiments are reported in which the subjects had to respond to a target that masked a preceding prime via metacontrast masking. In one part of Experiment l, the subjects discriminated the target's shape (square or diamond) by a motor-choice reaction, and in another part they had to respond with a simple reaction. The prime was neutral (circular) with respect to the target's shape. The data showed a facilitation effect. In both tasks the reaction time was reduced by the masked prime. However, the reduction was more pronounced with simple reaction than with choice reaction. In the other experiments, additional primes were used with the same angular shapes as the targets. In Experiments 2 and 3, after discriminating the target's shape by a choice reaction, the subjects had to judge the prime's shape in a signal-detection task. While neither the d' value for discriminating the angular primes from the circular ones (Exp. 2) nor the d' value for distinguishing between the angular primes (Exp. 3) was different from zero, the choice-reaction data showed a congruency effect. With a congruent prime (i.e., a prime that had the same shape as the target), the reaction times were reduced. With an incongruent prime, the reaction times grew. In Experiment 4 the errors were investigated. The facilitation effect was present in the RT, but not in the number of errors, whereas the congruency effect was present in the number, but not in the RT of errors.While the facilitation effect can be attributed either to an unspecific activation by the masked prime or to an influence of the prime on attentional processes, the congruency effect can be explained by the assumption that the masked prime directly activates the specific response, which corresponds to the prime's shape.     

The relationship between space and time in the perception of stimuli moving behind a slit

When a shape defined by a set of dots plotted along its contour is presented in a sequence of frames within the boundaries of a slit, and in each frame only one dot (featureless frame) or two dots (feature frame) are displayed, a whole moving dotted shape is perceived. Masking techniques and psychophysical measures have been used to show that a dynamic random-dot mask interferes with shape identification, provided the interframe interval is greater than about 15 ms, and there are no stimulus features for recognition in individual frames. A similar pattern of results was obtained when the observer had only to detect the movement of a single dot or a pair of dots against a dynamic-noise background. It is concluded that the visual system can resolve the correspondence problem in both apparent movement (one moving dot) and aperture viewing (featureless-frame condition) by extracting motion before the extraction of features in each frame. However, the results also show that where feature identification in each frame is possible, it can also be used to identify the moving targets.     

Transfer of signed responses in American Sign Language from vocal English stimuli to physical object stimuli by a chimpanzee (Pan)

A chimpanzee was taught 10 signs of Ameslan (American Sign Language) using only vocal English words as stimuli. The corresponding physical objects were items found in the subject's home environment, and which he frequently encountered during daily activities. Reference was not made to these items during teaching sessions. Each teaching session was followed by a test session in which the objects were silently presented to the subject and the question What that? was signed to him. The subject acquired all 10 signs in response to the English word stimuli and then successfully transferred these signs to their physical object referents during testing.     

Habituation of exploratory activity to new stimuli, to the absence of a previously presented stimulus and to new contexts, in rats

Rats trained to run a shuttle-alleyway for food exhibited exploratory behaviour to a novel visual/tactual stimulus presented in a specific place of the alley. Intermittent presentation of the same stimulus in the same place resulted in reduction of the exploratory activity (habituation), both within and between sessions. The animals also directed exploratory activity to the absence of the previously presented stimulus at the place where the stimulus had been presented before; this latter response also habituated. The presentation (1) of the same stimulus to which the animals had already habituated in another place in the alleyway or when the animals were running in an opposite direction to the previous trials of stimulus presentation, or (2) of another stimulus, resulted, again, in the appearance of exploratory activity. These results lead to the conclusion that the animals code external events, store this information, and use it to detect spatial- and directional-contextual changes and to generate predictions about that specific environment.