Effect of inconsistent distinctiveness of artificial semantic features on retrieval speed

A purported universal of language is the generalization of distinctive features, for example, in phonology and semantics, within a language or an individual. This could be due to a tendency either to use or to ignore a feature depending on whether or not it has previously been distinctive. This mechanism is shown to operate in retrieval of well-learned artificial concept names. Several simple models of performance cannot account for this effect. The apparent inefficiency of possible mechanisms which could account for this result suggests that it may reflect a special predisposition.     

A COMPARATIVE STUDY OF INSTRUMENTAL LEARNING BY PRESCHOOL CHILDREN IN PAPUA NEW GUINEA AND AUSTRALIA1

Instrumental learning of preschool children in Papua New Guinea (PNG) and Australia (AUST) was compared using two tasks (imitative and nonimitative) and two rewards (social and nonsocial). There were no differences between the two groups in the rate of acquisition measure of trials to criterion. PNG children made more late responses during acquisition and, for nil responses, there were group x task and group x reward x task effects. In the extinction phase, there were two main effects for trials to criterion: PNG children were more resistant to extinction than AUST children, and there was greater persistence in responding after social reward regardless of nationality. Reward x group, reward x task, and reward x group x task interactions also were observed in the extinction trials to criterion. In addition, there were three main task effects during extinction for other responses: on the imitative task, more wrong responses were made, and on the nonimitative task, more extra responses and more paired responses were made. A subsidiary analysis compared the two culturally different but educationally similar groups comprising the PNG sample: no major differences were isolated in acquisition or extinction.     

Semi-automated desensitization : a controlled clinical trial

A clinical trial of semi-automated desensitization on phobic patients. Twelve received treatment with a therapist present and 12 received treatment from pre-recorded tapes. Therapy lasted a maximum of 16 weekly sessions. Assessment of progress was by means of self-ratings of phobic behaviour and more global fear ratings, made by the referring psychiatrist. Both treatments produced beneficial results. Both ratings agreed in finding no significant differences between the two methods of administration, thus confirming results from existing non-clinical trials of automated desensitization. Regardless of treatment group, agoraphobics and social phobics tended to improve less markedly, and less rapidly than simple phobics. Some implications of automated therapy for clinical practice are discussed.     

A rate measure of the relative aversiveness of signalled vs unsignalled shock

Five rats were trained on a two-component multiple schedule with each component consisting of a two-link chain schedule. Differential response suppression in the initial links of the chain schedules was used as a measure of the relative aversiveness of events introduced into the subsequent terminal links. When unsignalled shock was scheduled in one terminal link and signalled shock in the other (in addition to equal numbers of food reinforcers), responding was suppressed to a greater degree in the initial link preceding the unsignalled-shock condition. Reversing the terminal-link positions of unsignalled shock and signalled shock led to a reversal of the differential response suppression in the initial links. These results confirm previous findings that signalled shock is less aversive than unsignalled shock and extend the generality of this phenomenon from choice measures to rate measures of aversiveness.     

Perceptual dependence: Evidence for an internal threshold

Ss were asked to make two forced-choice discriminations on each trial: in Experiment I, they had to tell on which side of the display a latter pair appeared and whether or not its members were identical; in Experiment II, to say where the pair appeared and whether it consisted of Xs or Os; in Experiment III, to say where a letter appeared and whether it rhymed with E; and in Experiment IV, to say whether a letter pair was presented and whether it was a word. In Experiment III, and for some Ss in Experiment I, the second discrimination was dependent on the first; that is, when the S was wrong on the first, he performed at chance level on the second. In Experiment IV, when Ss indicated that nothing was presented (with confidence), they performed at chance level on the recognition task; thus, recognition was dependent upon some information about the detection task. It is argued that perceptual dependence implies that a threshold state, a state in which the S has no information, exists for the dependent discrimination. One explanation of dependence assumes mediation of the dependent discrimination by a processing stage which succeeds stages mediating the other task.     

Aggression and heat: the influence of ambient temperature, negative affect, and a cooling drink on physical aggression.

Two experiments were conducted to examine the influence of ambient temperature upon physical aggression. In the first, male subjects received either a positive or negative evaluation from a confederate and were then provided with an opportunity to agress against this person by means of electric shock. On the basis of previous research, it was predicted that high ambient temperatures (92-95 degrees F) would facilitate aggression by those receiving positive evaluations but actually inhibit such behavior by those receiving negative assessments. Results confirmed both of these predictions and also indicated that more moderate but still uncomfortably warm temperatures (82-85 degrees F) produced similar effects. The second experiment employed procedures similar to the first and examined the suggestion that administration of a cooling drink would reduce the impact of high ambient temperatures upon overt aggression. This prediction, too, was confirmed. The possible mediating role of negative affect with respect to the influence of ambient temperature and other environmental factors upon aggression was discussed.     

Effects of scopolamine on repeated acquisition of radial-arm maze performance by rats.

Rats repeatedly acquired the performance of selecting only the four baited arms in an automated eight-arm radial maze, with the arms containing food pellets randomly assigned prior to each session. During each 14-trial (trial: obtain all four pellets) daily session, the number of errors (selecting nonbaited arms or repeating arm selections) showed a within-session decline, and choice accuracy for the first four arm selections showed a positive acceleration across trials for all rats. An index-of-curvature statistic, calculated for total errors, was used to quantify both the within- and between-session improvement of performance. Scopolamine (0.03 to 0.3 mg/kg, ip), but not methylscopolamine (0.3 mg/kg), reduced the accuracy of the first four selections of each trial and increased total within-session errors for all rats. Session times also were increased by scopolamine. An examination of within-session accuracy showed only slight signs of improvement at the higher dosages of scopolamine. The results indicate that behavior in transition states maintained by reinforcement contingencies in the radial maze is similar to that maintained by extended chained schedules, despite the fact that some of the stimuli controlling behavior in the maze are absent at the moment behavior is emitted.     

Inhibition by Reinforcement: Effects of Reinforcer Magnitude and Timeout on Fixed-Ratio Pausing

The Psychological Record - Rats were trained on fixed-ratio schedules with different reinforcer magnitudes (concentrations of sweetened milk), using procedures in which responding was allowed to...