Limbic networks and associative learning: II. Entorhinal contributions to spontaneous alternation, passive avoidance, and taste aversion learning

The hippocampus plays an important role in learning and memory, but the precise nature of that involvement remains uncertain. Transection of the perforant path, a primary input pathway to the hippocampus, has been shown to produce changes in reaction to novelty and acquisition of active avoidance; the nature and magnitude of these changes vary with lateral or medial perforant path damage. In a series of experiments on adult rats, the role of these pathways in spontaneous alternation, exploration, acquisition and extinction of conditioned responses, passive avoidance, and conditioned taste aversion was investigated. Lateral transection reduced exploration while medial transection facilitated acquisition of an active avoidance response; no effects were observed on any other measure. Results are discussed in terms of what perforant path damage might reveal regarding the interactions of the hippocampus with other brain regions.     

Effects of transient coronary artery occlusion on canine intrinsic cardiac neuronal activity

In order to further elucidate the regulatory function of canine epicardial neurons, the effects of transient coronary artery occlusion on their spontaneous activity was studied. Fifty-eight individual, spontaneously active units were identified by means of their action potential configurations in specific loci of atrial and ventricular epicardial fat of 10 anesthetized dogs. The activity of 49 of the units was modified by one minute of coronary artery occlusion. Twenty-four of the 49 responding units exhibited increased activity and 37 decreased activity during coronary artery occlusions. Activity changes were sometimes, but not always, associated with decreased left ventricular intramyocardial systolic pressure. During reperfusion, the activity of 6 units was increased compared to control levels, even though ventricular pressures remained the same. Following acute decentralization, 48% of previously active units generated spontaneous activity; the activity of 89% of these was altered during coronary artery occlusion despite the fact that overall cardiodynamics were unchanged. Following hexamethonium administration, the activity generated by 9 of 10 spontaneously active units was modified by coronary artery occlusion. It is concluded that transient coronary artery occlusion can modify the activity generated by intrinsic cardiac neurons, such modification involving central and peripheral neuronal interactions.     

The phenomenology of spatial integration: data and models

A briefly presented visual stimulus followed by darkness seems to persist beyond its physical offset. We are concerned here with the relation between two characteristics of this visible persistence: first, its phenomenological resemblance to the stimulus that spawned it and second, its usefulness as a basis for integrating visual stimuli that are separated in time. We describe two experiments using a task in which two halves of a visual stimulus were presented successively and observers reported how complete the stimulus appeared to be. Stimuli appeared less complete with increases in both the duration of the interval intervening between presentation of the two halves and the duration of the initially presented stimulus half. This data pattern is similar to that obtained in tasks in which spatial integration of two temporally disparate stimuli is necessary for correct responding. On the basis of this similarity, we argue that phenomenological appearance and ability to integrate stimuli over time are two facets of the same perceptual events. We describe a formal model to account for these and other data.     

Novice Strategies for Understanding Paintings

Visual analysis is taught in art history classes as a skill which aids a student in understanding a work of art in its appropriate conceptual or historical context. To provide a foundation for the design of computer-based lessons to train students in the skill, this study attempted to discover the strategies that novices employ when viewing a set of paintings. Verbal protocols obtained from novices in this study indicated that they described semantic features, or content, of paintings more than the formal elements, e. g. line, colour, shape, when viewing realist paintings. However, when presented with abstract, i. e. less semantically accessible paintings, novices shaply altered their approach and discussed formal elements over content. These findings suggest that an analysis of formal elements is not performed by a novice when a painting depicts a clear subject, but is attempted when the subject-matter becomes obscure. This implies that, at some level, novices realize that the meaning of a painting can be extracted from attention to the formal elements. Interestingly, novice protocols contained the same categories of strategies deemed important by experts. The lack of training in visual analysis was not notably manifest with respect to style. Of all formal dimensions, this one yielded the greatest discrepancy between novices and the expectations of instructors.     

Phonological transformations in Spanish-speaking aphasics

Thirty-seven aphasic patients whose native language is Spanish were divided into four groups: (1) Broca's, (2) Wernicke's, (3) Conduction, and (4) Anomia. Phonological errors produced on repetition and object-naming tasks were analyzed in terms of type of transformation and degree of similarity between target and errors in terms of shared distinctive features. Segmental transformations were of the following types: (1) pure substitution, (2) pure addition, (3) deletion, (4) reduplicative addition (doublet creation)—anticipatory (right to left) or perseverative (left to right), (5) reduplicative substitution (doublet creation)—anticipatory or perseverative, and (6) mutual exchanges. Pure substitutions were the most prevalent, exchanges, the least. Some error types were found to differentiate significantly between aphasic populations. We suggest that different mechanisms may underlie the same error type for different aphasic populations.     

Enhanced recency effects with changing-state and primary-linguistic stimuli

A number of explanations for the modality effect in immediate serial recall have been proposed. The auditory advantage for recall of recency items has been explained in terms of (1) the contributions of precategorical acoustic storage (PAS), (2) an advantage of changing-state over static stimuli, and (3) an advantage of primary-linguistic coding. Four experiments were conducted to evaluate these hypotheses. In the first, subjects viewed seven consecutive rectangles of different colors on a computer monitor. A small recency effect was obtained when the task was to recall the colors of the rectangles in order, with the size of the effect being independent of whether the rectangles remained stationary on the screen or moved in one of four directions. However, when the task was to recall the direction of movement of the rectangles, a larger recency effect was found. This pattern of results was interpreted as suggesting that recency effects are enhanced by changing-state stimulus information, but only when the changing-state information serves to identify the stimulus. Experiments 2 and 3 provided converging evidence by demonstrating an analogous recency advantage for changing-state visual stimuli that were somewhat different from those of Experiment 1. Experiment 4 demonstrated recency effects with synthesized speech stimuli that were substantially greater than were those found with the changing-state visual stimuli of the first three experiments. Implications of the results for the PAS, changing-state, and primary-linguistic hypotheses, as well as temporal-distinctiveness theories of recency, are discussed.     

Pragmatic reasoning schemas

We propose that people typically reason about realistic situations using neither content-free syntactic inference rules nor representations of specific experiences. Rather, people reason using knowledge structures that we term pragmatic reasoning schemas, which are generalized sets of rules defined in relation to classes of goals. Three experiments examined the impact of a “permission schema” on deductive reasoning. Experiment 1 demonstrated that by evoking the permission schema it is possible to facilitate performance in Wason's selection paradigm for subjects who have had no experience with the specific content of the problems. Experiment 2 showed that a selection problem worded in terms of an abstract permission elicited better performance than one worded in terms of a concrete but arbitrary situation, providing evidence for an abstract permission schema that is free of domain-specific content. Experiment 3 provided evidence that evocation of a permission schema affects not only tasks requiring procedural knowledge, but also a linguistic rephrasing task requiring declarative knowledge. In particular, statements in the form if p then q were rephrased into the form p only if q with greater frequency for permission than for arbitrary statements, and rephrasings of permission statements produced a pattern of introduction of modals (must, can) totally unlike that observed for arbitrary conditional statements. Other pragmatic schemas, such as “causal” and “evidence” schemas can account for both linguistic and reasoning phenomena that alternative hypotheses fail to explain.     

Perceptions of school psychology services from a staff perspective

This investigation examined how staff in an elementary school district perceived their school psychologists and how these perceptions differed across components of service and staff groups. We developed a School Psychological Service Questionnaire and then analyzed responses from regular education teachers, special education teachers, principals, and school psychologists in an urban school district. Although the findings are numerous, most noteworthy are, first, that consumer groups in the district had different perceptions than school psychologists about how school psychologists allocate their time and how this time should be allocated in the future. Second, consumer perceptions of school psychologists' knowledge generally were favorable. Third, in terms of domains appropriate for involvement by school psychologists, a factor analysis of consumer ratings revealed three relatively clear dimensions of recommended service provision — special education activities, interpersonal or school-climate activities, and administrative responsibilities. Fourth, the helpfulness of school psychologists, as perceived by consumers, related positively to frequency of contact. Fifth, differences in perception of school psychological services were evident across staff groups. Finally, comparisons between master's level and doctoral level school psychologists suggested numerous differences in how the staff perceived these service providers.