The relation between infants' activity with objects and attention to object appearance

The authors examined the relation between infants' motor skills and attention to objects features in events in which a hand acted on an object (e.g., squeezed it) that then produced a sound (e.g., squeaking). In this study, 6- to 7-month-old infants (N = 41) were habituated to a single event and then tested with changes in appearance and action. Infants robustly responded to changes in action, but as a group did not respond to changes in appearance. Moreover, more skilled activity with objects during naturalistic play was associated with longer looking in response to a change in appearance, but not to a change in action. Implications for the relation between perception and action in infancy are discussed. (     

Alan Baron: A pioneer in translational science

Primates take longer to choose between alternatives with smaller differences in value. This effect—a particular instance of the distance effect in symbolic comparisons—has not been replicated in birds. Instead, birds appear to respond independently to each alternative, such that the latency to choose depends primarily on the alternative of highest value. Three experiments tested for the distance effect in pigeons under conditions not previously considered. Experiment 1 presented pigeons with forced‐ and binary free‐choice trials, where each alternative was one of three possible delays to reinforcement (4, 8, and 16 s). Pigeons were exposed to the choice stimuli for different amounts of time and with different sample response requirements prior to the choice response. Experiment 2 added a fourth (0‐s delay) alternative. Experiment 3 substituted the 16‐s delay with a second 4‐s delay. In all experiments, pigeons systematically chose the shortest delay to reinforcement. Latency to choose the 4‐s delay did not vary when choosing against the 8‐s or 16‐s delay, regardless of whether choice stimuli were exposed for the duration of nine pecks (Experiment 1), or whether a 0‐s delay alternative was sometimes present (Experiment 2). Latency to choose the preferred of two identical alternatives (4‐s vs. 4‐s) was shorter than the latency to choose between different alternatives (4‐s vs. 8‐s; Experiment 3); this is the opposite of a distance effect. These results show no evidence of a distance effect in pigeon choice, consistent with the hypothesis that pigeons respond independently to each choice alternative.     

Learning words in space and time: probing the mechanisms behind the suspicious-coincidence effect

A major debate in the study of word learning centers on the extension of categories to new items. The rational approach assumes that learners make structured inferences about category membership, whereas the mechanistic approach emphasizes the attentional and memory processes that form the basis of generalization behaviors. Recent support for the rational view comes from observations of the suspicious-coincidence effect: People generalize category membership narrowly when presented with three subordinate-level exemplars that share the same label and generalize category membership broadly when presented with one exemplar. Across three experiments, we examined the mechanistic basis of this effect. Results showed that the presentation of multiple subordinate-level exemplars led to narrow generalization only when the exemplars were presented simultaneously, even when the number of exemplars was increased from three to six. These data demonstrate that the suspicious-coincidence effect is firmly grounded in the general cognitive processes of attention, memory, and visual comparison.     

Learning how actions function: the role of outcomes in infants' representation of events

Action is a fundamental component of object representations. However, little is known about how infants represent actions performed on objects. Across four experiments, we tested the hypothesis that at 10 months of age (N = 80) infants represent the general ability of actions to produce outcomes (sounds). Experiments 1A and 1B showed that infants encode actions and associate actions and object appearances in events in which actions produced no sound outcomes. Experiment 2 showed that infants associate the presence or absence of outcomes with actions. Experiment 3 showed, in contrast, that infants did not associate the presence or absence of outcomes with object appearances. Together, these studies suggest that infants encode the outcome potential of specific actions. We discuss the implications of these findings for our understanding of the development of action representations.     

Verbal self-reports of delayed matching to sample by humans

Undergraduates participated in two experiments to develop methods for the experimental analysis of self-reports about behavior. The target behavior was the choice response in a delayed-matching-to-sample task in which monetary reinforcement was contingent upon both speed and accuracy of the choice. In Experiment 1, the temporal portion of the contingency was manipulated within each session, and the presence and absence of feedback about reinforcement was manipulated across sessions. As the time limits became stricter, target response speeds increased, but accuracy and reinforcement rates decreased. When feedback was withheld, further reductions in speed and reinforcement occurred, but only at the strictest time limit. Thus, the procedures were successful in producing systematic variation in the speed, accuracy, and reinforcement of the target behavior. Experiment 2 was designed to assess the influence of these characteristics on self-reports. In self-report conditions, each target response was followed by a computer-generated query: “Did you earn points?” The subject reported by pressing “Yes” or “No” buttons, with the sole consequence of advancing the session. In some cases, feedback about reinforcement of the target response followed the reports; in other cases it was withheld. Self-reports were less accurate when the target responses occurred under greater time pressure. When feedback was withheld, the speed of the target response influenced reports, in that the probability of a “Yes” report increased directly with the speed of accurate target responses. In addition, imposing the self-report procedure disrupted target performance by reducing response speeds at the strictest time limit. These results allow investigation of issues in both behavioral and cognitive psychology. More important, the overall order in the data suggests promise for the experimental analysis of self-reports by human subjects.     

Variable-interval schedules of timeout from avoidance: effects of chlordiazepoxide, CGS 8216, morphine, and naltrexone.

Rats were trained on concurrent schedules in which pressing one lever postponed shock and pressing the other occasionally (variable-interval schedule) produced a 2-min timeout during which the shock-postponement schedule was suspended and its correlated stimuli were removed. These procedures provided a baseline for studying the effects of drugs on behavior maintained by different sources of negative reinforcement (shock avoidance and timeout from avoidance). Experiment 1 studied a benzodiazepine agonist, chlordiazepoxide, and antagonist, CGS 8216. Chlordiazepoxide (2.5-30 mg/kg) had little effect on avoidance responding except at higher doses, when it reduced responding. By comparison, responding on the timeout lever was increased in 5 of 6 rats. These effects were reversed by CGS 8216 (2.5-5 mg/kg) in the 2 rats tested, but CGS 8216 had no effect by itself. Experiment 2 studied an opiate agonist, morphine, and antagonist, naltrexone, with 3 rats. Morphine's (2.5-20 mg/kg) effects were opposite those of chlordiazepoxide: At doses that either increased or had no effect on avoidance responding, morphine depressed timeout responding. Naltrexone (5 mg/kg) reversed these actions but had no effect by itself.     

The place of the human subject in the operant laboratory

Although laboratory study of human behavior seems an obvious vehicle for strengthening the scientific base of behavior analysis, the place of the human subject within the operant laboratory remains problematic. The prevailing research strategy has been to link principles developed with animals to human affairs, either through interpretation of naturally occurring human behaviors or through application of the principles to the solution of human problems. The paucity of laboratory research on human operant behavior derives from several misconceptions: the possibility that experimental demand characteristics and pre-experimental behavioral dispositions of human subjects contaminate the results; that ethical considerations place undue constraint on research topics and experimental designs; and that uncontrollable variation in subjects' histories and other relevant personal characteristics prevents observation of reliable functional relations. We argue that these problems do not pose insurmountable obstacles to the experimental analysis of human behavior; that adequate methods of control and analysis are available; and that operant techniques, by emphasizing experimentally imposed contingencies, are well suited for the laboratory study of human behavior.     

Computer-based methodology laboratories: 1. An undergraduate course in experimental psychology

At West Virginia University, microcomputers are used in the laboratory sections of a conventional undergraduate course on research methods in psychology. IBM-compatible computers and QuickBasic programs are used to duplicate the functions of equipment that is less reliable and, taken collectively, more expensive—equipment such as stimulus projectors, pursuit rotors, timers, and mirror tracing stands. The computer systems increase the speed and efficiency of data collection, reduce errors of procedure and measurement, and implement numerous steps to standardize procedures and limit extraneous influences. As a consequence, uncontrolled variability is minimized, and the opportunity for meaningful research outcomes is maximized. The laboratory can be expanded with software alone, without the expense of additional hardware.