Social factors influence solo and rat dyads exploration of an unfamiliar open field

Animal Cognition - Exploring new and unfamiliar environments is critical for survival, providing information on food, shelter, mates, and sources of danger. The open field paradigm is commonly used...     

A suit for protecting chronically implanted devices in monkeys

The plastic barrel suit provides complete protection of chronically implanted fistulas and electrical connectors. The lost time, expense, and the frustrations of having these devices damaged was avoided.     

Experimental design symbolization and model derivation

A method of design symbolization (DS) is given for a class of designs in which all factors are related by complete crossing or by nesting. Characterization of acceptable DS's, and logical relational properties are given. It is shown how the design model can be obtained from the DS.The preparation of this article was supported by NIH Grant GM-11128, and by grants to the Institute of Human Learning by NSF and NIH.     

The 3RT Test: Three reaction time tasks for IBM PC computers

The 3RT Test consists of a simple, a choice, and a conditional reaction time (RT) task. The three tasks involve comparable visual stimuli and require identical manual responses, but they differ in the complexity of cognitive processing required. The nonverbal stimuli convey commonly known meanings. Responses can be made either on the keyboard or on response keys connected to the computer’s serial port. The computer’s internal timer/counter is used for millisecond timing. The test administration program allows flexible setting of the test conditions. The data analysis program provides summary data not only for each RT task as a whole, but also for separate trial types within each task. Summary statistics include measures of variation and central value that are not affected by extreme scores. In addition to laboratory studies with normal adults, the 3RT Test is suitable for life-span developmental studies, cross-cultural comparisons, and other uses in various clinical settings.     

Potentiation of the pressor response to stress by tolbutamide in dogs

Tolbutamide has previously been shown to amplify the pressor effects of “exogenous” catecholamines in conscious dogs, possibly due to sensitization of the α₁-adrenoreceptor-mediated vasoconstriction. The objective of this study was to examine if tolbutamide also amplifies the pressor effects of “endogenous” catecholamines released during psychological stress (classical Pavlovian aversive conditioning). Experiments were conducted in β-adrenoreceptor-blocked (propranolol, 1 mg/kg, i.v.) conscious dogs (n=4) trained in classical aversive conditioning. Conditioning was accomplished by following a tone (CS+) with a 1/2 second shock; another tone (CS-) was not followed by any shock and served as control. With saline pretreatment, aversive conditioning (i.e., CS+) increased mean arterial pressure (MAP) only by approximately 4.7% when compared to CS-, whereas with tolbutamide (45 mg/kg, i.v.) pretreatment, the increase in MAP induced by CS+ beyond what was induced by the CS- (approximately 6.2%) was significantly (p<0.05) larger than that with saline pretreatment. In isolated canine femoral arterial segments (n=4), the vasoconstrictor effect of phenylephrine (an α₁-agonist) at 5×10^?6M (which was the EC₅₀ value) was amplified by 2×10^?2M of tolbutamide from 54.0±2.0% to 66.9±2.1%. In conclusion, tolbutamide amplifies the pressor effects of “endogenous” catecholamines in conscious dogs, possibly by sensitization of the α₁-adrenoreceptor-mediated vasoconstriction. This mechanism of action is novel and has not been reported with other agents.     

Asymmetries in the regulation of visually guided aiming

An experiment was conducted to examine the contribution of sensory information to asymmetries in manual aiming. Movements were performed in four vision conditions. In the full-vision condition (FV), subjects were afforded vision of both the hand and the target throughout the course of the movement. In the ambient-illumination-off condition (AO), the room lights were extinguished at movement initiation, preventing vision of the moving limb. In the target-off (TO) condition, the target was extinguished upon initiation of the movement. In a no-vision (NV) condition, ambient illumination was removed and the target was extinguished upon initiation of the response movement. Results indicated that accuracy was superior in the full-vision and target-off conditions and when movements were made by the right hand. Movements made by the right hand were also of shorter mean duration. The magnitudes of performance asymmetries were uninfluenced by vision condition. Analyses of movement kinematics revealed that movements made in conditions in which there was vision of the limb exhibited a greater number of discrete modifications of the movement trajectory. On an individual-trial basis, no relationship existed between accuracy and the occurrence of discrete modifications. These data suggest that although vision greatly enhances accuracy, discrete modifications subserved by vision reflect the imposition of nonfunctional zero-order control processes upon continuous higher-order control regimes.     

Assessment: what role the assessor?

The advent of automated assessment contains the seeds of both threat and promise for professional assessors. Placing the problem in the historical and sociological contexts, this article examines computer-based test interpretation (CBTI) and the frequently misunderstood role of actuarial data in relation to it. I argue that sound clinicianship is central not only to the development of adequate CBTI systems, but also to the systems' appropriate and skillful use in practice. When properly utilized by otherwise well-qualified clinicians, CBTI can substantially enhance practice.