A multidimensional scaling analysis of schizophrenics' and normals' perceptions of verbal similarity.

Compared the judgments of similarity of words by 14 paranoid and 14 nonparanoid schizophrenics (mean ages, 29.43 and 30.64 yrs, respectively) with those by 14 normals (mean age, 32.79 yrs). The judgments were analyzed using an individual-differences multidimensional scaling procedure. A greater judgmental consistency was obtained among the normals than among the paranoid schizophrenics and larger differences among stimulus dimensions, in their contributions to predictable judgmental variance, were obtained for the normals as compared with the schizophrenics, especially the paranoid schizophrenics. Stimulus dimensions resembling the potency, activity, and evaluative dimensions of the semantic differential were less influential in the judgments of the schizophrenics, especially those classified as paranoid, than in the judgments of the normals. Results are discussed in terms of overinclusiveness among schizophrenics in multidimensional similarity judgments, as well as in terms of the potential importance to schizophrenics' deficiencies in semantic interpretations of the reduced influence of relevant dimensions of meaning. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Size estimation, perceptual recognition, and cardiac rate response in acute paranoid and nonparanoid schizophrenics.

Studied perceptual response styles of 8 paranoid and 8 nonparanoid schizophrenics in a VA hospital using size estimation and perceptual recognition tasks. Eight alcoholic patients were used as controls. Only acute, actively psychotic, unmedicated schizophrenics were included. Heart rate responses were monitored during the performance of the tasks. Psychological task performance and concomitant physiological responses were analyzed and integrated. The size estimation results replicate earlier findings. During the perceptual recognition task, the paranoid Ss showed a unique "jump to conclusions" response strategy. Early responding and response rigidity was not found to be specific to paranoid schizophrenics. All schizophrenic Ss showed more large-magnitude heart rate response during both tasks. The relationship between perceptual responses and physiological responses differed among the groups. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Schizophrenic memory-search performance involving nonverbal stimulus properties.

Investigated schizophrenic memory-search performance by conducting a memory-search choice-reaction-time (CRT) task involving nonverbal stimulus properties (real-life sizes of items). Procedures were designed to diminish ambiguities concerning previous evidence of possible schizophrenic impairment in scanning and comparison operations involving memory-held items. Ss (aged 18–60 yrs) were 20 paranoid and 20 nonparanoid schizophrenics, 20 psychiatric controls, and 20 normal Ss. Results indicate that scanning and comparison operations proceeded at comparable rates among the schizophrenics and controls. On the other hand, rates of encoding the presented stimulation for a given trial (the trial's probe item) into a task-facilitative format proceeded at a slower rate among the paranoid Ss in particular. Discussion focuses on specific memory-search CRT paradigmatic conditions in which intact speed of memorial item comparisons tended to be most evident among these patients. Results resemble earlier observations of the present 2nd author (see record 1978-31872-001) on memory-search CRT performance among paranoid and nonparanoid schizophrenics when probe stimulation has remained in view throughout each trial. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Schizophrenia and the scanning cognitive control: A reevaluation.

In recent studies it has been inferred from performance on perceptual tasks, that paranoid schizophrenics showed extensive scanning and nonparanoid schizophrenics showed minimal scanning. Eye movements during free-search and size-judgment tasks were recorded for 14 paranoid and 14 nonparanoid schizophrenics, 14 psychotic depressives, and 14 control Ss. Medicated Ss showed lower eyemovement rate and fixation rate than nonmedicated Ss and controls, but there were no significant differences due to schizophrenia. There was a significant interaction between patient type and medication for size-judgment means, but all such differences were reduced to nonsignificance by training. Even after training, Ss showed greater variability in size judgments than controls. Results failed to support the notion of extensive or minimal scanning behavior of schizophrenics. Errors by the psychotic patients in making size judgments were not correlated with scanning behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feature sampling in detection: Implications for the measurement of perceptual independence.

The article presents the feature sampling signal detection (FS-SDT) model, an extension of the multivariate signal detection (SDT) model. The FS-SDT model assumes that, because of attentional shifts, different subsets of features are sampled for different presentations of the same multidimensional stimulus. Contrary to the SDT model, the FS-SDT model enables the estimation of pure perceptual effects that are uncontaminated by strategic attention shifts. The consideration of feature sampling in detection and identification opens a new perspective on the problem of measuring, respectively, the separability and integrality of stimulus dimensions. Disregarding feature sampling as a component process in detection and identification usually results in biased estimations of perceptual independence concepts relevant for judgments of whether stimulus dimensions are processed independently. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual independence: Definitions, models, and experimental paradigms.

Necessary distinctions in an analysis of the study of perceptual independence are: (1) between the definition of independence as zero correlation and its definition as performance parity, (2) between normative models of perceptual process and models of perceptual state, and (3) between experimental designs which use orthogonal stimulus inputs and those which use correlated inputs. Implications of this analysis are: (1) perceptual independence is not a unitary concept; (2) it can be studied most effectively with experiments using orthogonal inputs; (3) when correlated stimulus inputs are used, so many underlying assumptions have to be made that it is almost impossible not to find a model which satisfies both the concept of independence and any given experimental result; (4) state independence is intimately related to process independence; and (5) search for the locus of interaction is probably a more useful approach than trying to determine whether independence exists. (29 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual grouping in schizophrenia: Replication of Place and Gilmore.

E. Place and G. Gilmore (see record 1980-25819-001) found that schizophrenics, unlike control Ss failed to utilize gestalt grouping principles in a task involving line counting. The present investigation was a replication of that study but with several methodological refinements, including the subtyping of schizophrenics, a fixed exposure duration of 15 msec, and analyses of both raw and arcsin transformed data. Ss were 10 paranoid schizophrenic, 10 nonparanoid schizophrenic, and 10 nonschizophrenic patients (mean age 31 yrs) and 10 normal undergraduates. The basic findings of Place and Gilmore held, and the refinements utilized made no difference. Results are discussed in terms of a 2-stage model of perceptual processing that describes normal perception in terms of an intitial global structuring of the stimulus field and a secondary local analysis. Schizophrenics appear to use the 2nd processing stage regardless of the stimulus condition. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Quantitative modeling of visual attention processes in patients with Parkinson's disease: Effects of stimulus integrality on selective attention and dimensional integration.

Parkinson's disease (PD) patients and normal controls (NCs) were administered a series of visual attention tasks. The dimensional integration task required integration of information from 2 stimulus dimensions. The selective attention task required selective attention to 1 stimulus dimension while ignoring the other stimulus dimension. Both integral- and separable-dimension stimuli were examined. A series of quantitative models of attentional processing was applied to each participant's data. The results suggest that (a) PD patients were not impaired in integrating information from 2 stimulus dimensions, (b) PD patients were impaired in selective attention, (c) selective attention deficits in PD patients were not due to perceptual interference, and (d) PD patients were affected by manipulations of stimulus integrality and separability in much the same way as were NCs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Confluent paranoia in African American psychiatric patients: An empirical study of Ridley's typology.

This study examined C. R. Ridley's (1984) typology of paranoia in African Americans, which assumes orthogonal dimensions of culture and pathology in symptom expression. Median split of scores on the Cultural Mistrust Inventory and the scale of False Beliefs and Perceptions represented high and low levels of cultural paranoia and pathological paranoia, respectively. The 4 groups of Black patients were nonparanoia, cultural paranoia, pathological paranoia, and confluent paranoia. A Fenigstein Paranoia Scale manipulation check indicated that differences in paranoid symptom expression among the groups were partially supportive of Ridley's model, as were measures of perceptions of hostility and self-esteem. Omnibus tests of between-groups differences were significant for global assessment of functioning and number of symptoms recorded in patients' charts. Predicted pattern testing revealed a significant severity dimension in mean scores across paranoia groups for some measures of clinician-rated functioning but not others. SCID interviewers' ratings of cultural mistrust and number of times restrained (or secluded) were more consistent with a pattern representing a cultural dimension than a severity dimension across paranoia groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adaptation to aversive maternal control and perception of simultaneously presented evaluative cues: A further test of a developmental model of paranoid behavior.

The adaptive style theory proposes that given a sustained aversive maternal control experience children will come to adopt 1 of 2 perceptual orientations toward evaluative cues. The open-style adapter maintains vigilance to negative evaluative cues, whereas the closed-style adapter defends against negative cues. This postulate, also critical to a narrower model for paranoid development, was tested by exposing 78 male undergraduates to an array of evaluative words, which they were told came from a maternal source. The words were composed of favorable, neutral, and unfavorable adjectives. After a period during which the S could freely scan a display of these words, retention was tested by recognition procedures. As predicted, open-style Ss, considered to be predisposed to paranoid behavior, extracted the most negative meaning, and closed-style Ss were the most defended against negative meaning. This effect held only for cues having a maternal source. (20 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multidimensional analysis of male and female voices

This paper is a sequel to a study which showed that the dominant dimension for perceptual discrimination among normal voices was the male-female categorization and which also suggested that discrimination within the male-female categories utilized distinct dimenisons. The present study eliminates the male-female axis by treating the gender groups separately and making the within-category dimensions available for more sensitive analysis. The purpose was to determine the number and nature of perceptual parameters needed to explain judgments of voice similarity depending on talker sex and whether the stimulus sample was a sustained vowel or a short phrase. The similarity judgments were submitted to multidimensional analysis via INDSCAL and the resulting dimenisons were interpreted in terms of available acoustic measures and unidimensional voice-quality ratings of pitch, breathiness, hoarseness, nasality, and effort. The decisions of the listerners appeared to be influenced by both the sex of the speaker and the stimulus sample, although fundamental frequency (fo), was important for all judgments. Aside from the fo dimensions, judgments concerning male voices were related to vocal tract parameters, while similarity judgments of female voices were related to perceived glottal/vocal tranct differences. Formant structure was apparently important in judging the similarity of vowels for both sexes while perceptual glottal/temporal attributes may have been used as cues in the judgments of phrases.     

Orthographic processing in visual word recognition: A multiple read-out model.

A model of orthographic processing is described that postulates read-out from different information dimensions, determined by variable response criteria set on these dimensions. Performance in a perceptual identification task is simulated as the percentage of trials on which a noisy criterion set on the dimension of single word detector activity is reached. Two additional criteria set on the dimensions of total lexical activity and time from stimulus onset are hypothesized to be operational in the lexical decision task. These additional criteria flexibly adjust to changes in stimulus material and task demands. thus accounting for strategic influences on performance in this task. The model unifies results obtained in response-limited and data-limited paradigms and helps resolve a number of inconsistencies in the experimental literature that cannot be accommodated by other current models of visual word recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Homonymy in the lexicons of young children acquiring American Sign Language

The effect of stimulus factors such as interobject similarity and stimulus density on the recognition of objects across changes in view was investigated in five experiments. The recognition of objects across views was found to depend on the degree of interobject similarity and on stimulus density: recognition was view dependent when both interobject similarity and stimulus density were high, irrespective of the familiarity of the target object. However, when stimulus density or interobject similarity was low recognition was invariant to viewpoint. It was found that recognition was accomplished through view-dependent procedures when discriminability between objects was low. The findings are discussed in terms of an exemplar-based model in which the dimensions used for discriminating between objects are optimised to maximise the differences between the objects. This optimisation process is characterised as a perceptual 'ruler' which measures interobject similarity by stretching across objects in representational space. It is proposed that the 'ruler' optimises the feature differences between objects in such a way that recognition is view invariant but that such a process incurs a cost in discriminating between small feature differences, which results in view-dependent recognition performance.     

Cognitive processing of multidimensional stimuli in schizophrenia: Formal modeling of judgment speed and content.

This article presents a formal, mathematical account of relations between response times on simple cognitive tasks and content of complex judgments involving multiple stimulus dimensions for people with schizophrenia. Changes in multidimensional judgments were viewed as the result of interference from increased stages of encoding with respect to the individual dimensions. Information on dimensional properties encoded earlier in a judgment trial was considered to be more susceptible to loss over the rest of the trial, because of a larger number of encoding stages applied to the remaining dimensional properties. Model predictions were tested with samples of paranoid and nonparanoid schizophrenic participants and controls. Unidimensional encoding speed was assessed by reaction times in an explicit similarity ratings task, and multidimensional judgment content was assessed by the relative importance of different stimulus dimensions to participants' ratings in an implicit similarity ratings task. Results support validity of the model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On cross-modal similarity: The perceptual structure of pitch, loudness, and brightness.

Examined how pitch and loudness correspond to brightness. In Experiment 1, 16 Ss identified which of 2 lights more resembled each of 16 tones; in Experiment 2, 8 of the same 16 Ss rated the similarity of lights to lights, tones to tones, and lights to tones. (1) Pitch and loudness both contributed to cross-modal similarity, but for most Ss pitch contributed more. (2) Individuals differed as to whether pitch or loudness contributed more; these differences were consistent across matching and similarity scaling. (3) Cross-modal similarity depended largely on relative stimulus values. (4) Multidimensional scaling revealed 2 perceptual dimensions, loudness and pitch, with brightness common to both. A simple quantitative model can describe the cross-modal comparisons, compatible with the view that perceptual similarity may be characterized through a malleable spatial representation that is multimodal as well as multidimensional. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Polarity correspondence: A general principle for performance of speeded binary classification tasks.

Differences in performance with various stimulus-response mappings are among the most prevalent findings for binary choice reaction tasks. The authors show that perceptual or conceptual similarity is not necessary to obtain mapping effects; a type of structural similarity is sufficient. Specifically, stimulus and response alternatives are coded as positive and negative polarity along several dimensions, and polarity correspondence is sufficient to produce mapping effects. The authors make the case for this polarity correspondence principle using the literature on word-picture verification and then provide evidence that polarity correspondence is a determinant of mapping effects in orthogonal stimulus-response compatibility, numerical judgment, and implicit association tasks. The authors conclude by discussing implications of this principle for interpretation of results from binary choice tasks and future model development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of preliminary perceptual output on neuronal activity of the primary motor cortex.

Observations of single neurons in the primary motor cortex of 1 monkey provided evidence that preliminary perceptual information reaches the motor system before perceptual analysis is complete. Neurons were recorded during a task in which 1 stimulus was assigned to a wrist flexion response and another was assigned to wrist extension. Two stimuli were assigned to a no-go response; each was visually similar to either the flexion or the extension stimulus. When a no-go stimulus was presented, neurons responded with weaker versions of the discharge patterns exhibited to the visually similar stimulus requiring a movement, suggesting that neurons receive partial perceptual information favoring that movement. Functionally separate neuronal populations were identified, and differences in the activations of these provide evidence about the functional effects of preliminary perceptual output on movement control processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is paranoid status prognostic of good outcomes? It depends.

Better outcomes for psychiatric inpatients classified as paranoid rather than nonparanoid could be due to group differences in disability levels created by traditional classification approaches. Paranoid functioning, per se, may not predict good institutional outcomes. The authors retrieved community outcome data for 469 inpatients form 19 wards, a subsample of participants that had been previously examined during their inpatient stay. Paranoid groups showed better community outcomes as an artifact of differences in disability levels when classifications were based on the traditional approach that requires a predominance of paranoid over nonparanoid behavior. No differential outcomes appeared when classifications were based on dimensionally measured paranoid functioning alone. In fact, dispositions of patients suggest that staff view paranoid behavior as a negative rather than positive prognostic indicator. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relation between current diagnostic criteria for schizophrenia and the dimensions of premorbid adjustment, paranoid symptomatology, and chronicity.

46 broadly defined schizophrenics were diagnosed according to 7 current diagnostic criteria for schizophrenia, and the subtyping dimensions of premorbid adjustment, paranoid symptomatology, and chronicity were assessed. Despite the minimal overlap between many of these criteria, samples selected by each of these systems were comparable in terms of the 3 subtyping dimensions. Results indicate that patients diagnosed as schizophrenic by each of these criteria were similar to schizophrenics who failed to meet those particular criteria with respect to premorbid adjustment, paranoid symptomatology, and chronicity. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Invariance of perceptual spaces and perceptual separability of stimulus dimensions

This article reports an extension of a paradigm for studying processing of perceptual dimensions. The paradigm is the complete identification task with a feature-complete factorial design (FCFD) of stimuli providing data for multidimensional signal detection analyses. The extension uses blocks of trials with subsets of the FCFD stimulus set, allowing estimation of various d's for inferring perceptual separability (PS) of dimensions and for disambiguating stimulus configurations when PS fails. Results of 4 experiments found the following: PS of arc curvature and line orientation in a discrimination task (Experiment 1), increasing PS failure in detection of horizontal and vertical lines (Experiment 2a), 45 degrees and 135 degrees (Experiment 2b), and 50 degrees and 60 degrees oblique lines (Experiment 2c). In each experiment, corresponding d's remained equivalent across blocks with different stimulus subsets.