Stressed vowel perception in word recognition

The purpose of this study was to measure subjects' ability to detect deliberate stressed, front-vowel misarticulations embedded in two-syllable words. Reaction times to words with various vowel-height misarticulations were examined for 25 women to assess the effect of a specific vowel height change on listeners' ability to recognize a word. Statistical analysis indicated no significant differences between reaction times to initial, stressed vowel changes along the height dimension, suggesting that subjects responded similarly to all vowel errors on the detection task. This finding provides further evidence that stressed-vowel information may serve as a perceptual anchor in guiding a listener during word recognition.     

Instructional and probability manipulations of bias in multiletter matching

Ratcliff (1985) performed fits of his diffusion model to the results of multiletter-matching experiments conducted by Ratcliff and Hacker (1981) and Proctor, Rao, and Hurst (1984), in which bias to respond "same" or "different" was manipulated by instructions and probabilities, respectively. The fits showed that both bias manipulations affected settings of a goodness-of-match criterion, whereas instructions also affected sensitivity. Evaluations of the experimental procedures and of Ratcliff's model-fitting procedures were performed in the present study. Three experiments showed that instructions and probabilities had similar effects, regardless of whether the different pairs were blocked or randomized according to the number of mismatching positions. The most salient feature of the results--that "same" reaction times were traded off more than were "different" reaction times, with no corresponding asymmetry in the error rates--was evident in all situations. The evaluation of Ratcliff's model-fitting procedures indicated that the apparent influence of instructions on sensitivity likely is an artifact of unequal variance for the sets of same and different pairs. Moreover, the effects of bias can be explained in terms of settings of response criteria, rather than of the goodness-of-match criterion, as in Ratcliff's fits.     

Apparent motion: evidence of the influence of shape, slant, and size on the correspondence process

Four stimulus elements configured as a notional diamond were flashed in pairs to elicit apparent motion. When the elements were identical (4 Zs), the direction of apparent motion was ambiguous. When the elements were pairs of different letters (Cs and Os, Es and Zs), letters of different sizes (Zs and zs), or oppositely oblique lines, the direction of apparent motion tended to be between identical elements. This was true, however, only for an initial, brief observation period. Subsequently, the direction of apparent motion tended to be determined by the direction of motion perceived at first, regardless of the character of the elements. This quickly established directional set (within 10 sec) largely swamped any tendency to resolve correspondence in terms of a feature of the stimulus. It appears to be based on spatial rather than retinal or egocentric coordinates.     

Obstacle perception by congenitally blind children

The ability to perceive objects from a distance and navigate without vision depends principally on auditory information. Two experiments were conducted in order to assess this ability in congenitally blind children aged 4 to 12 years who had negligible amounts of visual experience or formal mobility training. In Experiment 1, children walked along a sidewalk toward a target location to get some candy. A box was placed along the path on some trials, and the children were instructed to avoid the box if it was present. The children spent more time in the region just in front of the box than in the region just behind it, indicating that they perceived the box and acted so as to navigate around it. In Experiment 2, children attempted to discriminate whether a nearby disk was on their left or on their right. The children performed at above-chance levels, again indicating distal perception of objects. The results of both experiments suggest that blind children with little or no visual experience or formal training utilize nonvisual information, presumably auditory, to perceive objects. The specific nature of this auditory information requires further investigation, but these findings imply that the underlying perceptual ability does not require experience in spatial vision or deliberate training and intervention.     

Individual gustatory reaction times to various groups of chemicals that provoke basic taste qualities

Reaction times (RTs) to four groups of substances that provoke different taste qualities were measured. Measurements for all substances with the same taste, equalized in perceived intensity and provoking a very strong taste, were made concurrently for each subject. The comparisons were made on the individual level. No significant differences in RTs to substances with the same taste quality were found. When the factor of perceived intensity is kept constant, no effect of the stimulus chemical composition on RTs seems to be present. RTs to stimuli with different tastes differ significantly, the shortest being to salt and the longest to bitter. The difference in RTs for sour and sweet substances is small, and the subjects were not all alike in terms of the order of RTs with respect to these stimuli.     

Comparability of WAIS and WAIS--R scores among mentally retarded adults

This study compared the performance on the WAIS and WAIS--R of 21 mentally retarded adults residing in an Intermediate Care Facility. Tests were administered in one order, the WAIS initially and the WAIS--R second, with approximately two years between testings. Significant differences were found on the WAIS and WAIS--R for Verbal, Performance and Full Scale IQs. This finding contrasts with the differences between the measures as reported in the WAIS--R manual.     

A quasi-nonmetric method for multidimensional scaling VIA an extended euclidean model

An Extended Two-Way Euclidean Multidimensional Scaling (MDS) model which assumes both common and specific dimensions is described and contrasted with the standard (Two-Way) MDS model. In this Extended Two-Way Euclidean model then stimuli (or other objects) are assumed to be characterized by coordinates onR common dimensions. In addition each stimulus is assumed to have a dimension (or dimensions) specific to it alone. The overall distance between objecti and objectj then is defined as the square root of the ordinary squared Euclidean distance plus terms denoting the specificity of each object. The specificity,s _j , can be thought of as the sum of squares of coordinates on those dimensions specific to objecti, all of which have nonzero coordinatesonly for objecti. (In practice, we may think of there being just one such specific dimension for each object, as this situation is mathematically indistinguishable from the case in which there are more than one.)We further assume that _ij =F(d _ij ) +e _ij where _ij is the proximity value (e.g., similarity or dissimilarity) of objectsi andj,d _ij is the extended Euclidean distance defined above, whilee _ij is an error term assumed i.i.d.N(0, ²).F is assumed either a linear function (in the metric case) or a monotone spline of specified form (in the quasi-nonmetric case). A numerical procedure alternating a modified Newton-Raphson algorithm with an algorithm for fitting an optimal monotone spline (or linear function) is used to secure maximum likelihood estimates of the paramstatistics) can be used to test hypotheses about the number of common dimensions, and/or the existence of specific (in addition toR common) dimensions.This approach is illustrated with applications to both artificial data and real data on judged similarity of nations.     

Decision time and movement time in depression: differential effects of practice before and after clinical improvement

Choice reaction time involves, at least two components of response latency, decision time and movement time. Studies of choice reaction time usually provide values of these two components averaged over a given number of trials. The aim of the present study of depressed subjects was to investigate changes across practice on Decision Time (DT) and Movement Time (MT) before and after clinical improvement. 19 depressed subjects were given two sessions of 50 trials each, one before treatment (Di) and one after recovery (Df). Decision time and movement time exhibited quite different patterns. Decision time significantly decreased with clinical improvement. No significant variation across trials was found, in either session. Movement time values varied across trials but the variations observed on Di and Df were significantly different, whereas before treatment latencies recorded at the end of the session were greater than those scored at the start, the contrary was observed after clinical recovery. No significant difference was found between values of movement time scored at the start of the two sessions.     

The individual interview in couples treatment

This paper describes the use of concurrent individual and conjoint sessions in couples psychotherapy. The introduction of these individual interviews is seen as supporting the individual changes which must be made to effect change in the structure of the relationship. The benefits of this interventive scheme in dynamically oriented couples' treatment will be illustrated through the presentation of case examples.