TEMPORAL CONTROL ON INTERVAL SCHEDULES: WHAT DETERMINES THE POSTREINFORCEMENT PAUSE?

On fixed-interval or response-initiated delay schedules of reinforcement, the average pause following food presentation is proportional to the interfood interval. Moreover, when a number of intervals of different durations occur in a programmed cyclic series, postreinforcement pauses track the changes in interval value. What controls the duration of postreinforcement pauses under these conditions? Staddon, Wynne, and Higa (1991), in their linear waiting model, propose control by the preceding interfood interval. Another possibility is that delay to reinforcement, signaled by a key peck and/or stimulus change, determines the subsequent pause. The experiments reported here examined the role of these two possible time markers by studying the performance of pigeons under a chained cyclic fixed-interval procedure. The data support the linear waiting model, but suggest that more than the immediately preceding interfood interval plays a role in temporal control.     

When do children overestimate their knowledge of unfamiliar targets?

We report four investigations in which 5 to 7 year olds judged whether or not they knew familiar- and unfamiliar-named targets. Under some conditions judgments were made in relation to performance on a relevant task, e.g., children judged whether they knew the picture they had picked from a set was the target. Under other conditions, children judged their state of knowledge not in relation to performance, e.g., they answered "Do you know who (target) is?" Under both types of condition, children nearly always made correct "know" judgments when targets were familiar. Correct "don't know" judgments about unfamiliar targets were relatively common when judgments were not made in relation to performance on a task (average scores 80-90% correct), but were less frequent when knowledge was judged in relation to performance on a task (average scores 40-70% correct). Knowledge judged in relation to performance was overestimated even when children did not choose the picture they thought might be the target before making their judgment, when the pictures were face-down, and when children predicted performance on a task not yet present. It seems that although children can make relatively accurate judgments of their own knowledge states, they tend to overestimate their competence when assessing their knowledge in relation to performance on a task. We discuss why this might be.     

Sex differences in visual-spatial ability: The role of performance factors

Two studies were designed to explore the role of performance factors as sources of the frequently noted higher male scores on visual-spatial ability tests. In the first study, the mental rotations test (MRT) was administered to male and female college students of equally high quantitative ability (based on SAT math scores). Although males had significantly more correct responses on the test than did females, their advantage was eliminated when the ratio of correct responses to items attempted was used as the dependent measure. In the second study, the same test was administered to new groups of male and female college students. In this sample, the males had significantly higher SAT math scores. The MRT was administered under standard, timed conditions and under untimed conditions. Both raw and ratio scores were calculated. With SAT math score as the covariate, analyses of covariance indicated that males demonstrated higher performance in the timed, raw-score condition but not in the untimed or in the ratio-score conditions. The theoretical and social policy implications of these studies are discussed.     

WOMEN'S PRIME OF LIFE Is It the 50s?

The hypothesis is advanced that the early 50s is women's prime of life, an androgynous time of good health combined with autonomy and relational security. In a sample of 700 college alumnae, aged 26–80, who were studied in 1983, women in their early 50s most often described their lives as "first-rate." In a longitudinal sample from the same institution in 1989, women in their early 50s also rated their quality of life as high. Conditions distinguishing the early 50s from earlier and/or later periods of the middle years included more "empty nests," better health, higher income, and more concern for parents. All but the last of these conditions were related to quality of life within each sample of "prime" women. In both samples, "prime" women showed confidence, involvement, security, and breadth of personality. Prime of life is offered as a useful concept in adult development.     

Client preferences for informed consent information

Thirty-five current therapy clients, 47 former clients, and 42 college students with no therapy experience rated 27 items in terms of importance for inclusion in informed consent discussions. The current and former client samples rated information about inappropriate therapeutic techniques, confidentiality, and the risks of alternative treatments as most important, and information about the personal characteristics of the therapist and the therapist's degree as least important. The results of this study provide evidence for differential informed consent disclosure practices.     

Variation of Isometric Response Force in the Rat

Hungry, unrestrained rats (N = 7) were rewarded for pressing a response beam in excess of 11 different force requirements. Changes in peak force production as a function of peak force requirement were examined by analyses of the first four moments of distributions of peak response forces: constant error, the within-subject standard deviation, skewness, and kurtosis. Results were similar to those previously obtained with human subjects: Constant error was positive at low and negative at high force requirements, the within-subject standard deviation increased as a negatively accelerating function of force requirement, and skewness and kurtosis were positive at low force requirements and decreased to negative values at the highest increments. Additional analyses of response kinetics indicated that rats, like humans, meet increasing force requirements by altering the rate of rise of force. The performance similarities suggest that common processes are engaged by the human and rat motor control systems to solve the problem of generating forces that are appropriate to the prevailing environmental constraints.     

Exposure-based models of human parsing: Evidence for the use of coarse-grained (nonlexical) statistical records

Several current models of human parsing maintain that initial structural decisions are influenced (or tuned) by the listener's or reader's prior contact with language. The precise workings of these models depend upon the grain, or level of detail, at which previous exposures to language are analyzed and used to influence parsing decisions. Some models are premised upon the use of fine-grained records (such as lexical cooccurrence statistics). Others use coarser measures. The present paper considers the viability of models based exclusively on the use of fine-grained lexical records. The results of several studies are reviewed and the evidence suggests that, if they are to account for the data, experience-based parsers must draw upon records or representations that capture statistical regularities beyond the lexical level. This poses problems for several parsing models in the literature.Aspects of this work were supported by ESRC grant No. R0023 4062 to Don Mitchell, by a Spanish Government grant DGICVT No. PB-92-0656-C04-02 to Fernando Cuetos, and by the Belgian National Fonds voor Wetenschappelijk Onderzoek, of which Marc Brysbaert is a Research Associate. We are grateful to Chuck Clifton, Barbara Hemforth, Martin Pickering, Matt Traxler, and an anonymous reviewer-all of whom made helpful comments on an earlier draft of the paper.     

Aggressivity,inattention, hyperactivity,and impulsivity in boys at high and low risk for substance abuse

Aggressivity, inattention, hyperactivity, and impulsivity are cardinal dimensions of externalizing behavior problems of childhood. They are diagnostic and clinical features of childhood disorders, and are thought to be linked to the subsequent development of adult disorders such as substance abuse (SA). Little is known, however, about the convergent and discriminant validity of these four constructs. We used multiple measures to develop indices of aggressivity, inattention, hyperactivity, and impulsivity in a sample of 10- to 12-year-old boys (N=183) with and without a family history of SA. Data were taken from mother reports, child reports, teacher reports, and laboratory tasks. The study aims were (1) to test the convergent and discriminant validity of aggressivity, inattention, hyperactivity, and impulsivity; (2) to examine whether the data were consistent with a model specifying the four constructs as indicators of one superordinate factor; and (3) to differentiate boys with and without a family history of SA in construct scores. The results supported the convergent and discriminant validity of the four constructs. Although discriminable, the constructs covaried strongly and were consistent with a model specifying them as indicators of a single superordinate factor. Boys with a family history of substance abuse scored higher than control boys on aggressivity, inattention, and impulsivity scores, but the groups did not differ on hyperactivity scores. The results are discussed in terms of the role of childhood behavior problems in vulnerability to SA.This work was supported by the National Institute on Drug Abuse grant No. DA 05605.     

SPEECH PERCEPTION AS A TALKER-CONTINGENT PROCESS

Abstract— To determine how familiarity with a talker's voice affects perception of spoken words, we trained two groups of subjects to recognize a set of voices over a 9-day period One group then identified novel words produced by the same set of talkers at four signal-to-noise ratios Control subjects identified the same words produced by a different set of talkers The results showed that the ability to identify a talker's voice improved intelligibility of novel words produced by that talker The results suggest that speech perception may involve talker-contingent processes whereby perceptual learning of aspects of the vocal source facilitates the subsequent phonetic analysis of the acoustic signal