A Bayesian prediction of four-look recognition performance from one-look data: II

In a recent paper, four-look recognition performance was predicted from one-look (lL) data by Bayes’s theorem, with the entire pattern of two Ss’ four-look data being predicted reasonably well. In the present study, three Ss were run, with the addition that feedback was given and confidence judgments were required. Their task was to identify tachistoscopically presented graphemes A, T, or U. Predictions of four-look performance were made using three orders of lL data matrices, differing in the breakdown of confidence categories. The three matrices led to reasonably accurate predictions. Predictions varied somewhat in accuracy, depending on the order of the lL matrix. The possibility that the variation in predictive accuracy reflected the capacity of an S to combine information received from each observation was discussed. The capacity question is presently under investigation by the authors.     

Anticipatory coarticulation in aphasia: acoustic and perceptual data

Two experiments investigated speech motor planning in aphasia by contrasting the degree of labial and lingual anticipatory coarticulation evident in normal subjects' speech with that found in the speech of aphasic subjects. In the first experiment, Linear Predictive Coding (LPC) analyses were conducted for the initial consonants of CV [si su ti tu ki ku] and CCV [sti stu ski sku] productions by 6 normal and 10 aphasic (5 anterior, 5 posterior) subjects. For normal subjects' productions, reliable coarticulatory shift was found for almost all measurements, indicating that acoustic correlates for anticipatory coarticulation obtain for [s], [t], and [k] in a prevocalic environment, as well as when [s] is the initial consonant of a CCV syllable. The data for the aphasic subjects were statistically indistinguishable from those of the normal subject group, and there were no differences noted as a function of aphasia type. In the second experiment, a subset of the consonantal stimuli produced by the normal and aphasic subjects was presented to a group of 10 naive listeners for a vowel identification task. Listeners were able to identify the productions of all subjects at a level well above chance. In addition, small but statistically significant Group differences were observed, with the [sV], [skV], and [tV] productions by anterior aphasics showing significantly lower perceptual scores than those of normal subjects.     

Accurate reading by nonlexical means: A case study

Accurate reading of irregular words is generally assumed to require intact lexical reading mechanisms. A nonlexical mechanism is usually deemed insufficient for this type of stimulus processing. The maximum level of accuracy attainable by nonlexical means, however, has not been adequately evaluated. We now describe a patient with acquired dyslexia due to impaired lexical reading mechanisms who retained the ability to read irregular words. The patient's poor performance on tasks requiring lexical decision and access to word meaning provided evidence that his lexical mechanisms were impaired. Nevertheless, errors on irregular words became apparent only with special tests that circumvented the patient's ability to use his intact speaking vocabulary to ensure that reading responses were words. The results demonstrate that relatively accurate reading of irregular words is possible despite damage to lexical mechanisms and that this can be achieved by filtering potential responses through the speaking vocabulary.     

Plucks and bows are not categorically perceived

Letter-like targets (a circle and a square) were presented in one of two fixed and cued visual field locations and were shown alone, flanked by a noise stimulus on the peripheral side (side of target farthest from fixation), on the central side, or on both sides simultaneously. The adjacent target and noise stimulus borders had similar featural properties (both curved or both straight lines) or dissimilar properties (one being a curved line and one a straight line). Each of 10 subjects made a go, no-go response only when his or her designated target appeared in a display. The results showed: (1) single targets were discriminated more accurately and more rapidly than were targets shown simultaneously with noise stimuli, (2) targets having dissimilar border relationships with noise items were discriminated more accurately than were targets having similar border relationships, (3) targets in central-noise displays were discriminated more accurately and rapidly than were targets in peripheral-noise displays, and (4) there was no interaction between border relationships and noise position. The principal result relating to target-noise border featural relationship was consistent with predictions derived from models which place the locus of noise effects at the stage of stimulus feature extraction. Aspects of the results were, however, seen to be consistent with both feature extraction and response competition conceptualizations.     

Couple interaction: A study of the punctuation process

This study examined couples' punctuation of their own interactions. The association between causal explanations for the interactions on issues involving differences and the nature of relatedness (i.e., degree of distress) was the major purpose of the study. Punctuation was defined as a way of grouping sequences of interactions. Punctuational differneces were operationalized by measuring couples' causal explanations and attributions of responsibility concerning their own interactions. Twenty distressed and non-distressed couples, matched on age, income, education, and length of relationship, participated in an intensive 3-hour interview conducted at their homes. Two relationship measures to determine the degree of distress were administered. The interview involved: generating issues of important differences, improvisational role plays of interactions, responses to open-ended questions about self and other perspectives, and rankings of causal explanations and attributions of responsibility about the interactions. The results suggested that the nature of relatedness, as defined by degree of distress, was associated with the punctuation of interactions by the communicators, tentatively supporting the Watzlawicket al. (1967) metacommunicational axiom. The main finding was that distressed couples attributed responsibility to the mate rather than self, whereas in nondistressed douples responsibility was shared.This article is based on a doctoral dissertation submitted to the University of Massachusetts, Amherst. The senior author is affiliated with the Department of Psychiatry, University of California, San Francisco