Biomedical subjects

J T Wixted

Publications and source records attributed to J T Wixted.

8 recordsLinked to original sources

PubMed1992

Subjective memorability and the mirror effect.

The mirror effect refers to the common finding that hit and false alarm rates on a recognition test are inversely related. The present research investigated the generality of the mirror effect (to rare words) and tested whether the effect might be grounded in accurate estimates of word memorability. The first 2 experiments showed that although high- and low-frequency words exhibit a mirror effect, rare words do not. Furthermore, contrary to expectations, Ss consistently (and mistakenly) predicted that memorability was directly correlated with frequency of usage. These findings weight against the idea that the mirror effect arises because of a S's ability to reject low-frequency lures on the grounds that such words would have been remembered had they appeared previously. Instead, the rejection of lures from different frequency categories may be determined by their semantic or phonemic overlap with list targets, and an analysis along these lines may help to explain why rare words constitute an exception to the otherwise ubiquitous mirror effect.

Adult↗

PubMed1991

Conditions and consequences of maintenance rehearsal.

The present experiments investigated the idea that the anticipated delay to initial recall governs whether a subject will rely on elaborative or maintenance rehearsal. In agreement with earlier research, the results suggested that maintenance rehearsal is used only when words can be rehearsed up to the moment of recall. A novel finding concerned the accessibility of the items processed in that way. When subjects were explicitly asked to recall those items first in final free recall, they were as likely to be recalled as items that had been processed elaboratively. This finding suggests that even rote rehearsal creates an accessible memory trace, albeit one that is most efficiently accessed by contextual rather than semantic cues.

Humans↗

PubMed1990

Social competence in schizophrenia: premorbid adjustment, social skill, and domains of functioning.

The relations between premorbid adjustment, social skill, and domains of functioning (symptoms, social adjustment) were examined in a group of 107 schizophrenic, schizoaffective, and affective disorder patients. Premorbid sexual adjustment was moderately correlated with social skill in the schizophrenic and schizoaffective patients. Schizophrenic patients had the lowest premorbid adjustment and social skill, followed by schizoaffectives, and then affective patients. Within the schizophrenic group, social skill was significantly related to both current social adjustment and negative symptoms, but not positive symptoms. Similar but weaker effects were found for premorbid adjustment. The results suggest that deficits in social skill are correlated with poor premorbid and morbid social adjustment of schizophrenics.

Adolescent↗

PubMed1990

Positive and negative symptoms in schizophrenia. A cluster-analytic approach.

The relationships between positive and negative symptoms of schizophrenia and between negative symptoms and social dysfunction were investigated using cluster analysis. Clustering across schizophrenic subjects produced three distinct groups, each characterized by some mix of positive and negative symptoms. Clustering across symptoms and behavioral variables produced a cluster comprising negative symptoms and measures of social adjustment and an additional cluster comprising only measures of social skill. A series of correlations revealed a positive relationship between positive and negative symptom measures. chi 2 analysis revealed a significant relationship between the cluster solution across subjects and classification of patients according to negative symptoms based on previously published criteria. Results are discussed in terms of the implications for the further development and refinement of subclassification schemes for schizophrenia.

Adult↗

PubMed1990

An analysis of social competence in schizophrenia.

Twenty-one schizophrenics with prominent negative symptoms were compared with 37 schizophrenics without them, 33 patients with major affective disorder and 20 non-patient controls on a battery of measures including a role-play test of social skills, the Social Adjustment Scale, and the Quality of Life Scale. The negative schizophrenics were most impaired on every subscale of each measure, followed in order by the non-negative schizophrenics, affective disorder patients, and non-patient controls. The social skill measures were not correlated with positive symptom levels, but were highly correlated with measures of community functioning. The results are consistent with the hypothesis that social dysfunction results from focal deficits in social skills.

Adolescent↗

PubMed1988

The linear system theory's account of behavior maintained by variable-ratio schedules.

The mathematical theory of linear systems, which has been used successfully to describe behavior maintained by variable-interval schedules, is extended to describe behavior maintained by variable-ratio schedules. The result of the analysis is a pair of equations, one of which expresses response rate on a variable-ratio schedule as a function of the mean ratio requirement (n) that the schedule arranges. The other equation expresses response rate on a variable-ratio schedule as a function of reinforcement rate. Both equations accurately describe existing data from variable-ratio schedules. The theory accounts for two additional characteristics of behavior maintained by variable-ratio schedules; namely, the appearance of strained, two-valued (i.e., zero or very rapid) responding at large ns, and the abrupt cessation of responding at a boundary n. The theory also accounts for differences between behavior on variable-interval and variable-ratio schedules, including (a) the occurrence of strained responding on variable-ratio but not on variable-interval schedules, (b) the abrupt cessation of responding on occurrence of higher response rates on variable-ratio than on variable-interval schedules. Furthermore, given data from a series of variable-interval schedules and from a series of concurrent variable-ratio variable-interval schedules, the theory permits quantitative prediction of many properties of behavior on single-alternative variable-ratio schedules. The linear system theory's combined account of behavior on variable-interval and variable-ratio schedules is superior to existing versions of six other mathematical theories of variable-interval and variable-ratio responding.

Animals↗

PubMed1986

An equation for behavioral contrast.

Pigeons were trained on a three-component multiple schedule in which the rates of reinforcement in the various components were systematically varied. Response rates were described by an equation that posits that the response-strengthening effects of reinforcement are inversely related to the context of reinforcement in which it occurs, and that the context is calculated as the weighted average of the various sources of reinforcement in the situation. The quality of fits was comparable to that found with previous quantitative analyses of concurrent schedules, especially for relative response rates, with over 90% of the variance accounted for in every case. As with previous research, reinforcements in the component that was to follow received greater weights in determining the context than did reinforcements in the preceding component.

Animals↗

PubMed1986

Variable-ratio schedules as variable-interval schedules with linear feedback loops.

The mathematical theory of linear systems has been used successfully to describe responding on variable-interval (VI) schedules. In the simplest extension of the theory to the variable-ratio (VR) case, VR schedules are treated as if they were VI schedules with linear feedback loops. The assumption entailed by this approach, namely, that VR and VI-plus-linear-feedback schedules are equivalent, was tested by comparing responding on the two types of schedule. Four human subjects' lever pressing produced monetary reinforcers on five VR schedules, and on five VI schedules with linear feedback loops that reproduced the feedback properties of the VR schedules. Pressing was initiated by instructions in 2 subjects, and was shaped by successive approximation in the other 2. The different methods of response initiation did not have differential effects on behavior. For each of the 4 subjects, the VR and the comparable VI-plus-linear-feedback schedules generated similar average response rates and similar response patterns. The subjects' behavior on both types of schedule was similar to that of avian and rodent species on VR schedules. These results indicate that the assumption entailed by the VI-plus-linear-feedback approach to the VR case is valid and, consequently, that the approach is worth pursuing. The results also confute interresponse-time theories of schedule performance, which require interval and ratio contingencies to produce different response rates.

Adult↗