A single unstable visual cue impairs spatial learning in a water maze

The role of a prominent visual cue (a light) in spatial learning was examined. Rats were trained to locate a hidden platform in a 4-arm radial water maze. For some rats the light predicted platform location. For other rats the light moved from trial to trial and did not predict platform location. While the predictive light did not facilitate performance above that seen in rats trained without a light, the moving light significantly impaired performance. In a second experiment, the temporal parameters of the moving light were manipulated. For one group the light was visible for the entire trial. In a second group the light was visible only before the rats reached the platform and in a third group the light was visible only after the rats reached the platform. The moving light impaired performance only when it was presented for the entire trial. When rats were subsequently retrained with a new platform location and a moving light in the familiar room, the light did not impair performance in any of the groups. We suggest that the prominent visual cue served as a directional cue, that competed with other directional cues, in the unfamiliar environment and interfered with performance.     

A room with a view and a polarizing cue: individual differences in the stimulus control of place navigation and passive latent learning in the water maze

We investigated individual differences in the stimulus control of navigational behavior in the water maze by comparing measures of place learning in one environment to measures of latent learning (via passive placement on the goal platform) in a novel environment. In the first experiment, 12 rats were trained to find a slightly submerged hidden platform at a fixed location in room A for 10 days (4 trials/day). Fast and slow place learners were identified by their mean escape latency and cumulative distance to the goal during acquisition. The same animals were then given a 2-min passive placement on the submerged platform in room B. Latent learning was assessed by the animal's escape latency on a single swim trial immediately following the placement in room B. The results showed that the good latent learners in room B were not necessarily the fast place learners in room A. This weak correlation may be related to the fact that some rats swam near the area in room B that corresponded to the former goal location in room A relative to a common polarizing cue (i.e., the door/entrance to both rooms). When the view of the door was blocked in a second experiment a significant positive correlation between place acquisition and the latent learning test was obtained, although escape performance following passive placement was not improved. These findings suggest that while place navigation and latent learning via passive placement may involve some common cognitive-spatial function, other associative (S-S and/or S-R) processes that occur during place navigation/active movement may be required for animals to exhibit truly accurate navigational behavior characteristic of asymptotic escape performance in the water maze. Additional implications for neurobiological studies using a procedural pretraining design are discussed.     

Some antiepileptic compounds impair learning by rats in a Morris water maze

In the present experiments, we investigated the effects of several commonly employed antiepileptic drugs on the performance of adult rats in a Morris water maze task. We found that phenytoin treatment produced the most deleterious performance impairments across all days of training, and that these performance deficits are not likely due to any general sensorimotor impairments. Carbamazepine had milder, but detectable negative effects, as carbamazepine-treated animals exhibited initial acquisition deficits, but rapidly achieved escape levels comparable to controls. In marked contrast, valproate and ethosuximide had no detectable effects on learning in the water maze. These results parallel previous findings in rats treated with these compounds and tested in an instrumental learning task, and are in general agreement with the human clinical literature. To the extent that one might wish to minimize learning deficits associated with maintenance on antiepileptic drugs, phenytoin is definitely not the treatment of choice, while valproate or ethosuximide are apparently much less disruptive.     

Incidental cue learning in rats

Continuity theories of discrimination learning appear to say that animals learn equally about all cues impinging upon their receptors; noncontinuity theories that they learn about only one cue at a time. Experiment I showed that neither of these positions is correct: rats trained to attend to one cue learned less about a subsequently introduced incidental cue than rats given no such pretraining; but attention to one cue did not totally prevent learning about the other. A second experiment established that if rats are trained with one cue, and a second cue is then also made relevant, the amount learned about this second cue varies directly with (a) the abruptness with which it is introduced, and (b) the difficulty of the original discrimination.     

Memory persistence of rats in a radial maze varies with training procedure

Different estimations of the time-course of spatial working memory have been reported. Some authors found working memory in the radial maze to be relatively long lasting, while others found more rapid exponential decay. In the present experiments it was attempted to account for the conflicting results by investigating the effects of different training procedures. Two types of training were examined under the same circumstances. A group of seven rats was given a series of delayed trials (5, 20, 60, and 120 min). Every delay was repeated at least four times and the delays were presented in an ascending order. The number of errors decreased at every delay except the last one (120 min), where error levels were constant (.50 errors/trial). The good performance was not based on use of intramaze cues or response chaining. In another group of seven rats the same delays were introduced in a quasi-random order and alternated with uninterrupted trials. The number of errors increased exponentially with the length of the delay. However, when this procedure was repeated, the number of errors decreased. These results suggest that training with delayed trials is a major factor to account for the differences in reports of memory persistence in the radial maze.     

Political skill and emotional cue learning via voices: a training study

The ability to discern emotional expressive cues represents an important interpersonal emotional skill at the workplace. In a training study with 123 employee–peer dyads, we examined whether political skill enhances the learning of emotional expressive cues via voices. Controlling for the effects of extraversion and self‐monitoring, it was found that political skill was significantly related to the accurate recognition of emotions via voices after a training session. As predicted, other‐reported political skill was found to be a stronger predictor of such learning than self‐reported political skill. In addition, social astuteness and networking ability were the most predictive of emotional cue learning among the different dimensions of political skill. Implications and limitations are discussed.     

Changes in cue associability across training in human causal learning

A series of experiments studied the amount learned about two food cues (A and B) whose presentation in a meal was followed by an allergy (+) in a fictitious patient. Participants were trained with A+ and C+ in Phase 1 and then with AB+ or AB++ in Phase 2. Subsequent testing revealed that BC was more allergenic than AD, showing that more had been learned about B than A in Phase 2. Participants were also trained with A+, then with AB+, and finally with AB++. The results of interpolating AB+ between A+ and AB++ training were consistent with the hypothesis that pretraining with Cue A selectively suppressed attention to its associate across the AB+ trials and, thereby, reduced the amount subsequently learned about B on AB++ trials.     

Water can induce better spatial memory performance than food in radial maze learning by rats1

Abstract: Two experiments were carried out to test the differential effects of hunger and thirst on memory performance. In Experiment 1, two groups of rats were exposed to an original radial‐maze task and then to a 30‐min retention‐memory task. The food‐deprived group completed the original task more quickly than the water‐deprived group, but the thirsty group mastered the memory task more quickly than the hungry group (p < 0.01). In Experiment 2, deprivation conditions were changed from the original to the memory task. The food‐water group completed the memory task more rapidly than the water‐food group (p < 0.05). Thirst proved to constitute a more favorable condition for retention‐memory learning. The applicability of several theories is discussed.     

Diazepam impairs place learning in the Morris water maze

The effect of diazepam (0.3, 1.0, and 3.0 mg/kg) on the acquisition and retention of place learning was evaluated. The analysis of escape latencies indicates that 1.0 and 3.0 mg/kg diazepam significantly impaired the retention of spatial information. When a free swim trial was carried out only control animals showed spatial bias to the target quadrant. The absence of spatial bias in the group that received 0.3 mg/kg suggests that the amnesic effect of diazepam can be seen at doses similar to or even lower than the anxiolytic ones, and that the GABA/benzodiazepine receptor complex is highly sensitive to the cognitive impairment induced by diazepam in spatial tasks.     

Effects of glucose on scopolamine-induced learning deficits in rats performing the Morris water maze task

In order to assess the effects of glucose on drug-induced spatial learning deficits, three experiments were conducted using the Morris water maze. Scopolamine and glucose were injected ip at various stages of training. Rats of Wistar strain served as subjects. In Experiment 1, scopolamine (0.4 mg/kg) and 10, 100, or 500 mg/kg of glucose were administered every day from the start of training, and the effect on acquisition was evaluated. In Experiment 2, scopolamine and 100 or 500 mg/kg of glucose were administered after 6 days of training, and the effect on performance was assessed. In Experiment 3, scopolamine and 500 mg/kg of glucose were injected after 2 days of training, and the effect on the following trial was tested. In all experiments, scopolamine impaired acquisition/performance of the task. Glucose at 500 mg/kg showed a significant enhancing effect on acquisition regardless of scopolamine injection only when injected daily from the start of training (Experiment 1). Glucose injected after the performance has reached asymptote (Experiment 2) did not affect performance, and glucose in the middle of training showed a slight but insignificant enhancing effect (Experiment 3). These results may suggest that the effect of glucose changes as a function of the degree of learning of the spatial learning task. The possibility of task specificity of the glucose effect was also discussed in relation to the cholinergic systems and local cerebral glucose utilization.     

Exploration, fear and maze learning in spontaneously hypertensive and normotensive rats

In this study the performance of normotensive (WKY) rats was compared with that of hypertensive (SHR) rats on a Novel Object Test, a standardized Fear Test, and the Hebb-William's maze. We found no strain differences for exploration; however, WKY rear and ambulate more than SHR near the walls of the apparatus. There were no strain differences apparent in the Fear Test. WKY showed markedly different behavior compared with SHR on the Hebb-William's maze; WKY showed a high level of stereotyped displacement behaviors and failed to improve their performance over successive trials. Overall, WKY appear to be more reactive to environmental conditions than SHR. The behavior of both strains is highly context dependent.     

Place and response learning of rats in a Morris water maze: differential effects of fimbria fornix and medial prefrontal cortex lesions

The question examined in this study is concerned with a possible functional dissociation between the hippocampal formation and the prefrontal cortex in spatial navigation. Wistar rats with hippocampal damage (inflicted by a bilateral lesion of the fimbria fornix), rats with damage to the medial prefrontal cortex, and control-operated rats were examined for their performance in either one of two different spatial tasks in a Morris water maze, a place learning task (requiring a locale system), or a response learning task (requiring a taxon system). Performance of the classical place learning (allocentric) task was found to be impaired in rats with lesions of the fimbria fornix, but not in rats with damage of the medial prefrontal cortex, while the opposite effect was found in the response learning (egocentric) task. These findings are indicative of a double functional dissociation of these two brain regions with respect to the two different forms of spatial navigation. When the place learning task was modified by relocating the platform, the impairment in animals with fimbria fornix lesions was even more pronounced than before, while the performance of animals with medial prefrontal cortex lesions was similar to that of their controls. When the task was again modified by changing the hidden platform for a clearly visible one (visual cue task), the animals with fimbria fornix lesions had, at least initially, shorter latencies than their controls. By contrast, in the animals with medial prefrontal cortex damage this change led to a slight increase in escape latency.     

Positive and negative cue redundancy in multiple cue probability learning

In two separate experiments, 80 introductory psychology students completed a two-cue probability learning task in which cue intercorrelation was positive or negative and cue validities were positive or negative. Results indicated that Ss did not learn the negative validity tasks. In addition, there were no significant differences between groups in achievement due to cue intercorrelation within any one experiment. However, the positive redundancy groups were significantly more consistent in the employment of their decision strategy than the negative redundancy groups when cue validities were positive. The negative redundancy groups were superior to positive redundancy groups in matching; again, when cue validities were positive.     

A room with a cue: personality judgments based on offices and bedrooms

The authors articulate a model specifying links between (a) individuals and the physical environments they occupy and (b) the environments and observers' impressions of the occupants. Two studies examined the basic phenomena underlying this model: Interobserver consensus, observer accuracy, cue utilization, and cue validity. Observer ratings based purely on offices or bedrooms were compared with self- and peer ratings of occupants and with physical features of the environments. Findings, which varied slightly across contexts and traits, suggest that (a) personal environments elicit similar impressions from independent observers, (b) observer impressions show some accuracy, (c) observers rely on valid cues in the rooms to form impressions of occupants, and (d) sex and race stereotypes partially mediate observer consensus and accuracy. Consensus and accuracy correlations were generally stronger than those found in zero-acquaintance research.