A multidimensional scaling analysis of 16 complex sounds

The INDSCAL multidimensional scaling model was used to investigate the distinctive features involved in the perception of 16 complex nonspeech sounds. The signals differed along four physical dimensions: fundamental frequency, waveform, formant frequency, and number of formants. Scaling results indicated that subjects’ similarity ratings could be accounted for by three psychological or perceptual dimensions. A statistically reliable correspondence was observed between these perceptual dimensions and the physical characteristics of fundamental frequency, waveform, and a combination of the two formant parameters. These results were further explored with Johnson’s (1967) hierarchical clustering analysis. Large differences in featural saliency occurred in the group data with fundamental accounting for more variability than the remaining dimensions. Further analysis of individual subject data revealed large individual differences in featural saliency. These differences were related to past musical experience of the subject and to earlier findings using similar signals. It was concluded that (1) the INDSCAL model provides a useful method for the analysis of auditory perception in the nonspeech mode, and (2) featural saliency in such sounds is likely to be determined by an unspecified attentional mechanism.     

Multidimensional scaling reveals two dimensions of thermal pain

The Individual Differences Scaling (INDSCAL) model of multidimensional scaling was used to explore the dimensions of thermal pain. The observers made 66 similarity judgments to all pairs of 12 different thermal stimulus intensities ranging from zero to noxious. Analysis of the data revealed a two-dimensional group stimulus space. The major dimension ordered the stimuli with respect to their intensity. This quantitative, strength-of-sensation dimension may be interpreted as indicating how weak or strong a stimulus feels, apart from any secondary qualities of warmth or pain. The second dimension was related to the qualitative aspects of the stimuli. This bipolar dimension contained two attributes: a pain attribute ranging from just detectable warmth to painful, and a warm-hot attribute running from just detectable warmth to hot. This study demonstrates the utility of the INDSCAL approach to the understanding of pain and offers a new technique for answering the age-old question concerning the number and qualities of the dimensions underlying the pain experience.     

Dimensions of the perception of art: verbal scales and similarity judgements

Abstract.— An INDSCAL analysis was performed on subjects' similarity judgements of all pairs of 12 landscape paintings. Three principal INDSCAL dimensions were identified by analysing responses to 24 unidimensional rating scales derived from previous experiments. The present findings, together with those of previously published studies, suggest that three of the principal dimensions of perception of art appear to be (1) Hedonic-Representational, (2) Clarity, (3) A Dynamic factor involving activity, balance and symmetry. It is suggested that although Complexity may be an important factor influencing responses to simple stimuli, its rôle in the perception of paintings is small, and has frequently been over-emphasised.     

Individual differences in perceived similarity and preference for visual art: A multidimensional scaling analysis

Previous studies have shown that individuals may attend to different dimensions in making an overall judgment of similarity between complex stimuli. The present study investigated the nature of differences in the perceived similarity of reproductions of paintings by the use of multidimensional scaling techniques. Using the INDSCAL model, a group of art-trained students are shown to differ significantly from a group of nonart students in terms of their differential weighing of a set of common dimensions. The same subjects’ preferences are examined in relation to these differences by use of the PREFMAP hierarchy of models. While the simplest (vector) model was found to be appropriate for almost all subjects, large differences in vector direction and average subject ideal-point location are found. Implications for future studies of responses to art are discussed.     

Internal representation of visual texture as the basis for the judgment of similarity

The relationship between Fourier spectra of visual textures (represented both by the actual frequency components and by the response of four hypothetical channels selectively sensitive to spatial frequency) and the perceptual appearance of the textures was investigated. Thirty textures were synthesized by combining seven spatial frequencies whose amplitudes were randomly chosen and then scaled to give an overall contrast of .9. Similarity judgments were collected using both the method of triadic comparison (two subjects, 4,060 trials each) and the method of paired comparison (six subjects, 435 trials each). The similarity judgments were subjected to MDSCAL and INDSCAL dimensions were found to be optimally oriented in terms of spatial frequency information without rotation. The seven spatial frequency components accounted for 90.6% of the variance in the 3-D INDSCAL space, while the four channels accounted for 91.8% of the variance in the first two dimensions. The data further suggest that the four channels may interact in an opponent process manner. The results support the idea that the visual internal representation of stimuli is based on spatial frequency analysis rather than feature extraction.     

An empirical comparison between some models for multidimensional scaling

Abstract.— The results of three methods for multidimensional scaling—Torgerson's metric analysis, a non-metric method (TORSCA), and a method dealing with individual differences in multidimensional scaling (INDSCAL)—were compared in experiments on rhythm experience and on perception of sound quality. The INDSCAL analysis seemed to be the most adequate method for treating the data in these experiments.     

The effects of spatial phase on reaction time to spatially filtered images

Summary Many studies of visual perception have used periodic stimuli such as sine-wave gratings and checker-board patterns. It is well known that reaction time (RT) to such stimuli increases with increasing spatial frequency and decreasing contrast. While this is the case with periodic stimuli it is not clear that these relationships obtain for aperiodic stimuli such as natural scenes. A digitized image of an object (a vase) was submitted to two-dimensional Fourier analysis. Four pairs of spatial frequency band-limited images were created for each image. Each pair consisted of a normal-phase (NP) and a scrambled-phase (SP) version, with the magnitude spectrum and space-averaged luminance the same within each pair. Filter band-widths were 1 octave wide. Manual RT was measured for onset and offset of each spatially filtered image. Mean RT for SP images increased significantly with increasing spatial frequency, while no other significant differences were found with the NP images. This suggests that the temporal processing of complex, aperiodic images is influenced by the spatial frequency and contrast of local regions within the image, rather than by the space-averaged contrast of the entire image, and cannot be predicted by global estimates of contrast and spatial frequency.     

Implicit Representations of Political Leaders: A Multidimensional Analysis

Implicit cognitive representations of 20 salient political personalities (10 domestic, 10 foreign) were studied in two samples (N₁= 121; N₂= 129) over a 1-year interval. The aim of the study was to elaborate multidimensional models of voting preference by (a) representing the cognitive dimensions used by subjects in perceiving politicians, (b) contrasting perceptions of domestic and foreign leaders, (c) evaluating the effects of time, and (d) assessing individual differences between subjects on political perception. Judgments were analyzed by Carroll and Chang's (1970) Individual Differences Multidimensional Scaling (INDSCAL) procedure. Results showed that three implicit dimensions, evaluation, ideology , and leadership qualities, underlied perceptions of both domestic and foreign politicians. There were greater changes in perceptions of foreign and left-of-center leaders over the year than in judgments of domestic and right-of-center leaders; and individual differences such as attitudes, personality, and cognitive style were also significantly related to cognitive representations of politicians. Results were discussed in terms of their implications for predictive models of voting behavior, and the use of these methods in large-scale political surveys and polls is suggested.     

Visual persistence of spatially filtered images

Periodic stimuli such as sine-wave gratings and checkerboard patterns have been used in many studies of visual perception. It is well known that with such stimuli, visual persistence increases as spatial frequency increases and as contrast decreases. It is not clear, however, that similar relationships obtain for aperiodic stimuli such as natural images. Digitized images of objects (a face and a vase) were submitted to two-dimensional Fourier analysis. Four pairs of spatial frequency band-limited images were created for each image. Each pair consisted of a normal (NP) and a scrambled (SP) phase version, with the magnitude spectrum and space-averaged luminance the same within each pair. Filter bandwidths were one octave wide. Threshold persistence was measured for each spatially filtered image. Visual persistence for SP images increased significantly as spatial frequency increased, whereas no significant differences were found for NP images. This suggests that the temporal processing of complex, aperiodic visual images is influenced by the spatial frequency and contrast of local features within the image and cannot be predicted by space-averaged estimates of contrast and spatial frequency.     

Performance on a face perception task is associated with empathy quotient scores, but not systemizing scores or participant sex

This preliminary study investigated whether individual differences in performance on a difficult social perception task (determining the sex of shape normalized, line drawn dynamic faces) are related to sex of observer, scores on an empathy quotient and scores on a systemizing quotient. Performance in the face perception task (N = 60) was above chance, indicating that participants could judge the sex of the degraded facial stimuli from dynamic information alone. There was a trend for women to be more accurate in their judgments of target sex than men, but regression analyses indicated that EQ scores alone predicted performance on the task. This study suggests that empathy may mediate sex differences in face perception abilities, and potentially other tasks in social perception.     

Perceived onset simultaneity of stimuli with unequal durations.

Temporal-order judgment was investigated for a pair of visual stimuli with different durations in order to check whether offset asynchrony can disturb the perception of the order/simultaneity of onset. In experiment 1 the point of subjective simultaneity was estimated by the method of adjustment. The difference in duration of the two stimuli in the pair was either 0 or 50 ms. It was found that the subject shifts the onset of the shorter stimulus towards the offset of the longer one to obtain a satisfying impression of simultaneity even though the subject was asked to ignore the events concerning the stimulus offset. In experiments 2 and 3 the method of constant stimulus was applied. Both experiments indicate that subjects, in spite of instruction, take into account the offset asynchrony in their judgment.     

Performance on a face perception task is associated with empathy quotient scores,but not systemizing scores or participant sex

This preliminary study investigated whether individual differences in performance on a difficult social perception task (determining the sex of shape normalized, line drawn dynamic faces) are related to sex of observer, scores on an empathy quotient and scores on a systemizing quotient. Performance in the face perception task (N = 60) was above chance, indicating that participants could judge the sex of the degraded facial stimuli from dynamic information alone. There was a trend for women to be more accurate in their judgments of target sex than men, but regression analyses indicated that EQ scores alone predicted performance on the task. This study suggests that empathy may mediate sex differences in face perception abilities, and potentially other tasks in social perception.     

Bilingualism and the perception of professional concepts

A selected set of professional concepts was subjected to analysis through two separate multidimensional scaling techniques, the INDSCAL and TORSCA models, to evaluate the intergroup perceptual differences of four experimental groups, made up of unilingual French, unilingual English and bilingual students. The linguistic relativism thesis provided the research hypotheses on the relationship between language access and usage and concept perception. The multidimensional scaling techniques were applied to the matrix of subjects' similarity judgments on pairs of concepts, thus enabling the identification of three dimensions. The dimensions were labelled as conjunctive, relational and disjunctive, and were assumed to be related to the criteria employed by the subjects in their similarity rankings. An analysis of variance of the individual saliences on each dimension provided evidence of linguistic relativism for both the relational and disjunctive dimensions. These findings support the contention that unilingual speakers of separate languages differ from each other and from bilingual speakers in their perception of professional concepts.     

Qualitative hemispheric differences in semantic category matching.

A unilateral category matching task with words as stimuli was employed to investigate semantic processing in the right and left hemispheres (RH, LH). An overall right visual field (RVF)/LH dominance was observed and performances were better than chance, also in the left visual field (LVF)/RH. A qualitative analysis of reaction times with individual differences multidimensional scaling (INDSCAL) revealed that LVF/RH INDSCAL solutions were significantly more differentiated in structure than RVF/LH solutions in terms of number and size of dimensions. These findings support a depth of activation hypothesis of hemispheric processing, with the LH rapidly and focally and the RH slowly and diffusely activating the semantic network.     

UNCERTAINTY OF COMPARATIVE JUDGEMENTS AND MULTIDIMENSIONAL STRUCTURE

An analysis of preferences with respect to silhouette drawings of nude females is presented. Systematic intransitivities were discovered. The dispersions of differences (comparatal dispersions) were shown to reflect the multidimensional structure of the stimuli, a finding expected on the basis of prior work. Difference ratings of these stimuli were analyzed by the TORSCA and INDSCAL procedures. The three stimulus dimensions all appeared in the multidimensional analyses.     

Mental Reinstatement of Context: Do individual differences in mental time travel and eyewitness occupation influence eyewitness performance over different delay intervals?

The Cognitive Interview is a memory‐enhancing interview protocol designed to optimise the access and retrieval of eyewitness memories. Its Mental Reinstatement of Context (MRC) component requires interviewees to mentally reconstruct the crime event they witnessed. Individual differences in mental time travel (MTT) relate to the extent to which a person mentally re‐experiences personal events from his or her past. Individual differences in MTT have been found to predict correct recall of a simulated crime event under immediate MRC recall conditions. To explore the relationship between MTT and performance under MRC conditions further, the present study presented a simulated crime video to 30 police officers and 26 members of the public. Eyewitness recall was tested under MRC conditions either immediately or 1 week later. Participants' general MTT and also MTT relating specifically to the crime video itself were measured via self‐report. Less correct information and more confabulations were produced after 1 week, but delay had no effect on the amount of incorrect information reported. No difference in recall was found between police officers and members of the public. Better quality MTT relating to the crime video was found to be a positive predictor of the amount of information correctly recalled under immediate conditions but not after 1 week. General MTT scores did not predict correct recall under either delay condition. Interviewers need to be aware that, due to individual differences, some witnesses may perform better under the MRC component than others.     

Speech perception without hearing

In this study of visual phonetic speech perception without accompanying auditory speech stimuli, adults with normal hearing (NH; n = 96) and with severely to profoundly impaired hearing (IH; n = 72) identified consonant-vowel (CV) nonsense syllables and words in isolation and in sentences. The measures of phonetic perception were the proportion of phonemes correct and the proportion of transmitted feature information for CVs, the proportion of phonemes correct for words, and the proportion of phonemes correct and the amount of phoneme substitution entropy for sentences. The results demonstrated greater sensitivity to phonetic information in the IH group. Transmitted feature information was related to isolated word scores for the IH group, but not for the NH group. Phoneme errors in sentences were more systematic in the IH than in the NH group. Individual differences in phonetic perception for CVs were more highly associated with word and sentence performance for the IH than for the NH group. The results suggest that the necessity to perceive speech without hearing can be associated with enhanced visual phonetic perception in some individuals.