Stimulus Classes Formation in Concurrent Discriminations in Rats as a Function of Overtraining

The Psychological Record - The present two experiments conducted a limited parametric study of the overtraining variable using a whole-partial reversal procedure in rats. Rats received two...     

Long-Term Retention of Olfactory Discrimination Learning Set in Rats

The Psychological Record - Six male Sprague-Dawley rats were used to examine the long-term retention of an olfactory discrimination learning set. Rats were trained on 30 odor-unique, 5-trial...     

Concurrent Performance of Gunner's and Robotics Operator's Tasks in a Multitasking Environment

In this study, we simulated a generic mounted crew station environment and conducted an experiment to examine the workload and performance of the combined position of gunner and robotics operator. Results showed that participants' gunnery task performances degraded significantly when he had to concurrently monitor, manage, or teleoperate an unmanned ground vehicle compared to the gunnery single task condition. For the robotics tasks, participants had the lowest performance when using the semi-autonomous robot, indicating overreliance on the aided target recognition capabilities available when task load was heavy (i.e., concurrent performance of the gunnery task). Participants' perceived workload increased consistently as the concurrent task conditions became more challenging. Individual difference factors such as spatial ability and perceived attentional control were found to correlate significantly with some of the performance measures. Implications for military personnel selection were discussed.     

Pupillary Reactions to Sexual,Aggressive, and Other Stimuli as a Function of Personality

This study investigated how well three personality measures, The Dream Incident Technique, the Edwards Personal Preference Schedule, and the Repression-Sensitization Scale, could predict pupillary dilation to a set of experimental stimuli. The stimuli were brief video sequences portraying themes of sex, aggression, achievement, affiliation, nurturance, dominance, and order. The Dream Incident Technique was most predictive of pupillary dilation to these scenes. The Edwards Personal Preference Schedule correlated only with self reports of stimulation. The R-S Scale was unrelated to either pupillary dilation or self report of stimulation.     

Transfer of Learning Between Concurrent and Matching (or Non-matching)-to-Sample Discriminations in Rats

Three experiments examined transfer of learning between a concurrent discrimination and a matching (or non-matching)-to-sample discrimination in rats. In Experiment 1, rats were trained to criterion (group NOT) or were overtrained (group OT) on two concurrent discriminations. Subsequently, group OT learned a matching (or non-matching) task more rapidly than did group NOT. In Experiment 2, rats were initially given matching (or nonmatching) tasks and then given whole or half reversal with these tasks. Group whole reversed faster than group half. In Experiment 3, two groups of rats were trained on matching (or non-matching) tasks, and then given concurrent discrimination training, followed by either whole or half reversal training (groups matching and non-matching). Another group (group control) received a pseudo-discrimination followed by the same training in Phases 2 and 3 as groups matching and non-matching. In groups matching and non-matching, rats learned the whole reversal more rapidly than the half reversal. But the opposite result was observed in group control. These findings suggest that transfer effects reported in Experiments 1 and 2 are governed by the same mechanism for the formation of associations between stimuli.     

Discrimination of Visual Patterns as a Function of Motivation and Frequency of Reinforcement

The influence of the content of statements regarding delay and the level of role involvement (free choice of verbalization condition, assignment to verbalization condition, or passive listening to statement) on self-control in 98 preschool boys and girls was investigated in a task in which the child's possession of accumulating candy rewards was made contingent upon the child's stopping further accumulation. Children who chose to verbalize the task-centered utterance waited longer before taking the rewards than did the children in the three conditions involving reward-centered statements. Children who were told to use the task-centered statement or who passively heard it waited longer than did children who were told to use the reward-centered statement or who passively heard it. Children who chose the reward-centered statement waited less than children in the other two reward-centered conditions. Children given no direction regarding what to do during the waiting period delayed less than children in the task-centered conditions and they delayed about the same as children in the reward-centered groups, suggesting that preschoolers spontaneously employed delay plans which did not maximally facilitate self-control.     

Probability of Stimulus Equivalence as a Function of Class Size vs. Number of Classes

The Psychological Record - Two experiments were conducted to study stimulus equivalence as a function of class size and number of classes. In the first experiment, equivalence was tested in 50...     

Gender Discrimination as a Function of Stereotypic and Counterstereotypic Behavior: A Cross-Cultural Study

This study investigated gender discriminatory behavior of early adolescents from a cross-cultural perspective. One hundred sixty 7th-graders (80 Israeli Arabs and 80 Israeli Jews) were presented with two male candidates for class representative, one outstanding candidate with traditional feminine interests and characteristics, and the other an average candidate with masculine interests and characteristics. Participants were asked to rate the candidates on various measures such as their own election choice, others' election choice, their prediction of the candidate's likelihood of being elected, and their affinity and willingness to engage in activities with the candidate. The results showed that while both Arab and Jewish participants discriminated against the feminine candidate, the Arab participants discriminated to a much greater degree. The results emphasize the important role that culture plays in gender discriminatory behavior.     

Paradoxical Sleep Deprivation and Sleep Recording Following Training in a Brightness Discrimination Avoidance Task in Sprague–Dawley Rats: Paradoxical Effects

Previously, we reported that posttraining paradoxical sleep deprivation (PSD) resulted in an enhancement of the subsequent avoidance performance for rats trained for 15 trials in a Y-maze brightness avoidance discrimination task. A series of experiments were conducted to try to further understand the reasons for results which were contrary to those of the bulk of the sleep-learning literature. Experiment 1 investigated the effectiveness of the PSD technique. Rats (N= 4) were sleep recorded while residing on a “swimming pool” apparatus for 24 h. Compared to their baseline values, all animals showed a very large reduction in paradoxical sleep and spent significantly more time awake. Slow-wave sleep was unchanged. In Experiment 2, proactive motor effects were tested. Rats were deprived of PS for 24 h and then tested in a hole board motor activity task. There was a slight effect of PS deprivation on the day following the PSD and no effect when the rats were retested 1 week later. Experiment 3 investigated possible proactive effects of PSD on avoidance performance. Rats exposed to PSD in the 24 h before training in the Y-maze task did not demonstrate any facilitative effect on the subsequent avoidance performance. Experiment 4 investigated the possibility that the PSD facilitative effect could be due to partial training. Rats were given 75 acquisition trials in the brightness discrimination Y-maze avoidance before being subjected to 24 h of PSD. PS-deprived animals showed superior avoidance scores compared to non-PSD controls when retested 24 h later. In Experiment 5, the same strain of rats (N= 11) were sleep recorded after exposure to a partial acquisition in a Y-maze brightness avoidance discrimination task. They were then continuously monitored for 4 consecutive days. The percent PS for the Trained rats was significantly lower than that for the Control animals. This drop in percent PS was not confined to any particular time period in the 24-h day. None of the other sleep parameters reached significance. Analyses of the present results suggest that PSD exerts its facilitative effects on posttraining consolidation processes. We present arguments suggesting that PSD can have effects opposite to those generally reported, in animals demonstrating poor avoidance abilities, in an avoidance task.     

The Importance of On-going Concurrent Activities as a Function of Age in Time- and Event-based Prospective Memory

Time-based prospective memory is assumed to involve more self-initiated activities than event-based prospective memory. As age negatively affects self-initiated activities, older participants will show more prospectivememory deterioration than younger participants in time-based tasks. Einstein, McDaniel, Richardson, Guynn, and Cunfer (1995) indeed observed such a decrement in time-based prospective memory while d'Ydewalle, Utsi, and Brunfaut (1996) obtained a better time-based than event-based prospective memory among elderly. The on-going concurrent activity in Einstein et al. (1995) involved answering general questions, whereas d'Ydewalle et al. (1996) used a face-identification task. In an attempt to explain the discrepant results, the present experiment compares time- and event-based memory with young and older participants using the two types of on-going task. However, the better performance of the older participants in the timebased prospective memory task is obtained in the two on-going tasks. A difference in timing constraints in the procedure may explain why the older participants in Einstein et al. (1995) did perform more poorly in the timebased task, whereas our ageing participants did not show such a deterioration, suggesting that the slowing down of mental activities may provide a better explanation than the increasing lack of self-initiated activities by the elderly. All age effects in prospective-memory performance disappear when performance on the target items (i.e. items where a prospective-memory response is required) in the on-going task is taken into account. We emphasise the need to study trade-offs in prospective-memory research as a prospective-memory task is always embedded in another (on-going) activity.     

Delayed Matching to Sample: Probability of Responding in Accord with Equivalence as a Function of Different Delays

The Psychological Record - The present series of 4 experiments investigated the probability of responding in accord with equivalence in adult human participants as a function of increasing or...     

Retardation in Human Discrimination Learning as a Consequence of Pre-exposure: Latent Inhibition or Negative Priming?

A series of experiments with human subjects, using black-and-white chequerboard patterns, demonstrated that non-reinforced pre-exposure could impair performance in a subsequent learning task. Subjects were invited to take part in a scenario similar to that of a computer simulated card game. Their task was to turn over a series of cards by mouse-clicking on a pack of cards lying face-down, and then to classify these cards intoone of twocategories. In a subsequent task, subjects were asked todiscriminate betweenpairs ofchequerboards, some of which had previously appeared in the initialcategorizationphase: either directly ('fronts') or incidentally ('backs') involved in categorization. In Experiment 1, for those stimuli used as the backs ofthe cards (thatis,those visible ontopof the packof cards), there was asignificant impairment in performance relative to non-pre-exposed control stimuli. Although the impairment appeared to be specific to the stimuli pre-exposed, when the pre-exposed 'backs' were minimally distorted in the discrimination task of Experiment 2, performance was still significantly impaired relative to non-pre-exposed control stimuli. The results of Experiment 2 donot support the interpretation that retardation in learning following masked pre-exposure in human experiments is comparable to latent inhibition following simple preexposure in other animals. Whilst the impairment in performance appears to be similar to that of latent inhibition, the results may, instead, be better understood in terms of the inhibitory processes involved in negative priming. If this is so, then serious doubt is cast on whether latent inhibition has ever been reliably demonstrated in adult humans.     

Efficiency of Learning as a Function of Practice Schedule and Initial Ability

2 groups of 50 Ss practiced a pursuit rotor skill under different schedules of practice. A massed practice (MP) group (40 sec. work, 20 sec. rest) performed just as well as a distributed practice (DP) group (20 sec. work, 20 sec. rest) on the first day of practice. However, after 24 hr. of interpolated rest MP Ss demonstrated significantly greater amounts of learning. A further analysis of the 15 high initial ability and 15 low initial ability Ss from each of the two main groups resulted in no statistical differences among these subgroups in Day 1 performance that could be attributed to the practice schedules; however, a significant Ability Level × Practice Schedule interaction was obtained for Day 2 performance. It was caused by the low ability Ss under MP learning relatively more than the high ability Ss under MP when compared to the two DP groups. Thus learning was seen as being a function not only of schedule of practice but also of initial ability level.     

Perceived Occurrence of the Second of Two Closely Spaced Stimuli in a Long Movement

A 75-deg. movement of the arm in the vertical plane was used to examine the conscious perception of the apparent time of occurrence of a reversal signal S₂. A marked perceptual delay was found whether S₂ occurred during or after the reaction time to the first stimulus. This finding was consistent with Henry’s memory drum theory of neuromotor response, as well as with the efference theory of conscious perception proposed by Festinger and associates.     

Motor Learning as a Function of KR Schedule and Characteristics of Task-Intrinsic Feedback

Forty participants (age range = 18–35 years) practiced 1 of 2 versions of an aiming task (with or without spring resistance). Knowledge of results (KR) was provided to them either immediately or after a delay of 2 trials. Immediate KR led to significantly more accurate performance during the 80 trials in acquisition but significantly less accurate performance on a 40-trial retention test given 24 hr after practice. In addition, the spring version of the task was performed significantly less accurately than the no-spring version on the 24-hr retention test. Most important, a significant interaction on the 24-hr retention test revealed that performance of the no-spring version of the task, when KR had been given after a 2-trial delay, was significantly more accurate than performance of the other 3 combinations of task version and KR schedule. The results suggest that KR dependency in motor skill learning is related to familiarity with task-intrinsic feedback in addition to the schedule on which KR is presented.     

Kinematic and Electromyographic Changes That Occur as a Function of Learning a Time-constrained Aiming Task

The present study attempted to examine the changes associated with learning two time-constrained aiming movements at the neuromuscular and behavioral levels of analysis. Electromyographic data and movement kinematics were used to assess changes due to practice. Eight right-handed females were required to perform a 45° horizontal forearm extension in either 200 ms or 500 ms for 100 trials on each of four consecutive days. Both groups demonstrated an improvement in performance and a decrease in within-subject variability in the endpoint response measures, movement trajectory, and myoelectric pattern. With practice, there was a decrease in the amount of cocontraction between the agonist and antagonist muscles during movement execution, which indicated an elimination of unwanted neural activity. For the 200 ms task, the acceleration profile became symmetrical and a triphasic myoelectric pattern became evident. The deceleratory phase of the 500 ms task was longer than the acceleratory phase, and a biphasic pattern became apparent. The results suggest that two different control strategies were developed in the execution of the two movements examined. In addition, the relative invariance of the spatial-temporal dependent measures, as compared to the variability of the EMG, led us to the conclusion that the movement planning hierarchy was concerned with the spatial-temporal domain, whereas the amplitude and timing of muscular activity were planned at a lower level and thus played a subordinate role in movement production.     

Observational Learning and the Role of Confinement in Pigeons: Suppression of Learning as a Function of Observing the Performance of a Conspecific

Observational learning of a successive discrimination problem by pigeons was studied using conspecifics as models responding for either contingent or noncontingent reinforcement. We found that observation of these models was associated with poorer performance on subsequent testing than was shown by a control group that learned without first observing conspecifics' performance. No significant difference was found between subjects without observational experience and another control group that was confined in the observation apparatus and observed an empty chamber only.