Strict and random alternation in concurrent variable-interval schedules

Six pigeons responded on pairs of concurrent variable-interval schedules with, in different parts, four different arrangements of alternation between schedules. Following a single switching-key response, alternation was either strict or random, and the alternative presented after a switch (the postswitch alternative) was either signaled by the location of the switching key or unsignaled. Generalized-matching analyses showed little difference in behavior among the different alternation arrangements, except the usual finding of lower sensitivity of response allocation than time allocation was eliminated by arranging random alternation. Patterns of interchangeover times were similar for all arrangements except signaled random alternation. Differences in behavior preceding the different postswitch alternatives were found in the signaled random alternation procedure. Preference was biased towards the color of the signaled postswitch alternative and showed increased sensitivity when the postswitch alternative was to be the one with the higher reinforcer rate. Interchangeover times were substantially shorter when the postswitch alternative was signaled to be different from the current alternative than when it was signaled to be the same. However, when separate reinforcer ratios were calculated for the different postswitch alternatives, those effects were eliminated or greatly reduced. We suggest that, although behavior is indeed influenced by the postswitch alternative, the mechanism is indirect. That is, the distributions of reinforcers between alternatives obtained before each postswitch alternative differ when those alternatives are signaled, and those distributions are discriminated, but the same relations between choice and relative reinforcement hold irrespective of which postswitch alternative is signaled.     

Private self-consciousness factors: relationships with need for cognition, locus of control, and obsessive thinking in Iran and the United States

The authors measured Internal State Awareness (ISA) and Self-Reflectiveness (SR) factors from the Private Self-Consciousness Scale in Iranian (N = 325) and U.S. (N = 401) university students. In both societies, positive correlations with Need for Cognition and Internal Control and negative correlations with external control and obsessive thinking confirmed ISA as an adaptive form of self-consciousness. In partial correlations in which the authors controlled for ISA, SR was associated cross-culturally with greater Obsessive Thinking. This outcome conformed with the authors' expectations that SR would have negative mental health implications, but other data revealed complexities in the SR association with adjustment. Differences between samples failed to yield any simple support for F. Fukuyama's (1992) suggestion that Iranians might be more "alienated" (pp. 236-237) in their psychological functioning. The present study most importantly offered cross-cultural evidence in favor of the claim that better measures of an introspective self-awareness need to be developed.     

Choice in a variable environment: visit patterns in the dynamics of choice

Molar and molecular views of behavior imply different approaches to data analysis. The molecular view privileges moment-to-moment analyses, whereas the molar view supports analysis of more and less extended activities. In concurrent performance, the molar view supports study of both extended patterns of choice and more local patterns of visiting the choice alternatives. Analysis of the present data illustrated the usefulness of investigating order at various levels of extendedness. Seven different reinforcer ratios were presented within each session, without cues to identify them, and pigeons pecked at two response keys that delivered food on variable-interval schedules. Choice changed rapidly within components as reinforcers were delivered and, following each reinforcer, shifted toward the alternative that produced it. If several reinforcers were delivered consecutively by one alternative, choice favored that alternative, but shifted more slowly with each new reinforcer. A discontinuation of such a series of reinforcers by the delivery of a reinforcer by the other alternative resulted in a large shift of choice toward that alternative. These effects were illuminated by analysis of visits to the two alternatives. Changes in visit length occurred primarily in the first postreinforcer visit to the repeatedly reinforced alternative. All other visits tended to be brief and equal. Performance showed multiple signs of moving in the direction of a fix-and-sample pattern that characterized steady-state performance in earlier experiments with many sessions of maintaining each schedule pair. The analyses of extended and local patterns illustrate the flexibility of a molar view of behavior.     

Effects of drawing on children's item recall

In four experiments, we used item recall tasks to investigate recent claims that young children's event recall can be facilitated by drawing. In Experiments 1 to 3, children of ages 5 to 8 years were tested 4 h after presentation for recall of a set of 25 items that had been presented in groups on a colored, segmented board. In Experiment 1, recall was enhanced by replacement of the objects on the board as they were recalled, but not by drawing them. In Experiments 2 and 3, drawing the board and objects concurrently with or just prior to verbal recall not only failed to facilitate recall, but significantly reduced the number of items reported by 5- to 6-year-olds. In Experiment 4, drawing again impaired recall of items that had been presented as paired associates. Overall, results indicate that under some conditions drawing can impair children's recall rather than facilitate it, as reported in several recent studies.     

Reinforcer-ratio variation and its effects on rate of adaptation

Six pigeons were trained in sessions that consisted of six or seven concurrent-schedule components, each of which could have a different reinforcer ratio arranged in it. The components were unsignaled and occurred in a random order separated by 10-s blackouts. The overall reinforcer rate arranged in each component was 2.22 reinforcers per minute. In Experiment 1, the range of reinforcer ratios in the seven components was varied from a condition in which the ratios were always 1:1, to a condition in which the ratios varied between concurrent variable-interval 27 s extinction (EXT) and concurrent extinction variable-interval 27 s (ratios of 1:EXT, 9:1, 3:1, 1:1, 1:3, 1:9, EXT:1). In Experiment 2, the range of reinforcer ratios was always 27:1 to 1:27, and the presence and absence of the intermediate reinforcer ratios used in Experiment 1 (9:1, 3:1, 1:1, 1:3, 1:9) were investigated. Log response-allocation ratios in components changed rapidly with increasing numbers of reinforcers in components, and Experiment 1 showed that sensitivity to reinforcement was usually higher when the range of reinforcer ratios was greater. When the range of reinforcer ratios was kept constant in Experiment 2, the presence or absence of less extreme reinforcer ratios had no clear effect on sensitivity. At a local level, individual reinforcers had predictable quantitative effects on response ratios: Successive same-alternative reinforcers in a component had rapidly diminishing effects in both experiments. Reinforcers obtained on the opposite alternative to one or more prior reinforcers always had large effects on preference, and these changes were greater when the range of reinforcer ratios was greater. The effects of such reinforcers in changing preference were enhanced, and produced clear preference reversals, when intermediate reinforcer ratios were absent in Experiment 2. Two processes, one local to reinforcers and one with a longer time course, may be necessary to account for these results.     

Examination of the screening properties of the personality diagnostic questionnaire 4+ (PDQ-4+) in a prison population

There is a high prevalence of personality disorder in most prison populations. Many pass through the system undiagnosed. A screening instrument would improve identification. This study examined the screening properties of the Personality Diagnostic Questionnaire-4+ (PDQ-4+) in prisoners convicted of violent and sexual offenses. A sample of British prisoners completed the self-report PDQ-4+ and were interviewed using the Structured Clinical Interview for DSM-IV Axis II disorders. When used to generate a total score, the PDQ-4+ had an acceptable overall accuracy as measured by the area under the Receiver Operating Characteristics (ROC) curve. The PDQ-4+ appears to have the properties suitable for use as a screening instrument, particularly when screening for the presence or absence of personality disorder rather than for individual personality disorder categories. A graph is presented from which choices of cut-off score for different combinations of sensitivity and specificity can be made. A cut off total score of 25 or above yielded near optimal sensitivity and specificity. The suggested cut off score for this population is lower than that previously suggested.     

Concurrent schedules: How responses per reinforcer affects estimates of sensitivity to reinforcement

Conventionally, when choice is measured under concurrent schedules, all responses are included. However, the class of all responses consists of 2 sub-classes which are discriminable by their properties: Reinforced responses always equal obtained reinforcers, while unreinforced responses are free to vary. As a result, the inclusion of reinforced responses in choice measures results in sensitivity values in generalized matching that are biased toward larger values, and this bias becomes extreme in some combinations of overall response and reinforcer rates. Different ways of varying concurrent-schedule values also affect estimated sensitivity and the linearity between choice based on all responses and reinforcer ratios. To avoid spurious results and comparisons, and as a matter of good practice, generalized-matching fits and measures should be done using only unreinforced responses.     

Does overall reinforcer rate affect discrimination of time‐based contingencies?

Overall reinforcer rate appears to affect choice. The mechanism for such an effect is uncertain, but may relate to reinforcer rate changing the discrimination of the relation between stimuli and reinforcers. We assessed whether a quantitative model based on a stimulus‐control approach could be used to account for the effects of overall reinforcer rate on choice under changing time‐based contingencies. On a two‐key concurrent schedule, the likely availability of a reinforcer reversed when a fixed time had elapsed since the last reinforcer, and the overall reinforcer rate was varied across conditions. Changes in the overall reinforcer rate produced a change in response bias, and some indication of a change in discrimination. These changes in bias and discrimination always occurred quickly, usually within the first session of a condition. The stimulus‐control approach provided an excellent account of the data, suggesting that changes in overall reinforcer rate affect choice because they alter the frequency of reinforcers obtained at different times, or in different stimulus contexts, and thus change the discriminated relation between stimuli and reinforcers. These findings support the notion that temporal and spatial discriminations can be understood in terms of discrimination of reinforcers across time and space.