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Complex social factors can influence physiological activity, behavior, and health, but little is known about how essential components of these factors (e.g., human association, observation) affect human physiology. To begin to address this issue, an experiment was conducted to contrast predictions from social facilitation, distraction/conflict, and physiological reactivity formulations regarding the physiological effects of mere observation. Skin conductance and heart rate were measured surreptitiously from 27 women during a period in which they believe that the experimenter was simply calibrating auditory and physiological recording equipment. Approximately half of the subjects were led to believe that they could be observed by the experimenter during this period, and the remainder were led to believe that they could not be observed. Following baseline recordings, a series of 10 orienting tones were presented. Predictions from the physiological reactivity formulation were supported: (a) no differences in basal levels of somatovisceral activity were found as a function of mere observation; (b) mere observation enhanced the skin conductance response to the initial orienting tone; and (c) these physiological differences were punctate, quickly dissipating and quickly habituating. Hence, mere observation has subtler physiological effects than thought previously. Implications are discussed regarding the possible mechanism underlying the stress-enhancing and stress-buffering effects of human association, and regarding the effects social and contextual factors may have in psychophysiological research. Results from an international survey, based on the responses of 57 authors of articles that have appeared in Psychophysiology since 1983, are reported to inform the latter discussion. Results suggest that, even when social factors in psychophysiological research are minimized or held constant within studies, subtle differences in the social context across studies within and across laboratories may contribute to the appearance that psychophysiological relationships are unreliable.

Three experiments were conducted to determine the time course and contents of CS representations through an examination of differential conditioning of the rabbit's nictitating membrane response to two serial compounds. One compound (A-X+) was always paired with the unconditioned stimulus, and the other (B-X-) was always presented alone. All three experiments entailed manipulation of the interstimulus interval between the initial distinctive element of each compound (A and B) and the second, shared element (X). The joint results revealed that (a) conditioned response acquisition to the initial elements depended on the presence of X in the A-X+ compound; (b) differentiation between A and B appeared across interstimulus intervals up to 4,600 ms; and (c) conditional control over responding following A and B appeared at interstimulus intervals of at least 4,600 ms and perhaps up to 12,600 ms. The results are discussed with respect to mechanisms of occasion setting, generalization, and configuration.

In our judgment, the Apple IIIFIRST system (Scandrett & Gormezano, 1980) is an efficient and versatile system for experimental control and data acquisition in classical conditioning experiments. However, these attributes would be of limited value if the system did not extract measures from our analog signals with a high degree of correspondence with our ruler measurement procedures. Accordingly, we determined the system's validity in extracting measures of CR occurrence and CR latency in three conditioning experiments. Pearson productmoment correlation coefficients indicated a very satisfactory degree of agreement on measurements made by the Apple IIIFIRST system and ruler. Moreover, intraclass correlations and analysis of variance procedures applied to percent CRs and CR latency revealed several small, but divergent, differences between ruler and computer measurement of CR latency across the three experiments. However, subsequent analyses of variance revealed that the number and pattern of significant sources of variation for ruler or computer measurements were virtually identical. Accordingly, we have concluded that our system can successfully replace our traditional method of ruler measurement.Recently, Scandrett and Gorrnezano (1980) reported the development of an Apple II/FIRST system to control classical conditioning experiments, collect analog data, and extract dependent variable measures of conditioning. With the selection of the Apple II microprocessor, we have been able to establish independent Apple II/FIRST systems for each of the three facilities composing the Iowa Conditioning Laboratories at a fraction of the cost of our previous DEC PDP-8/e system (Millenson, Kehoe, Tait, & Gormezano, 1973). Specifically, the three classical conditioning laboratories are controlled by individual Apple II/FIRST systems consisting of an Apple II with 48 KB of memory, AM9511 floating-point processor, Apple II disk drive, Sanyo 9-in. video monitor, two 8255 programmable peripheral interface (PPI) chips, each providing a 24-bit digital input/output (I/O) buffer, an 8253 programmable counter/timer configured to provide a real-time clock, and a 16-channel 8-bit A/D converter (ADC0816CCN)The hardware and software development presented in this report was supported, in part, by NSF Grants BNS 76-8561 and 80-05907, NIMH Grant MH 16841, and NIDA Grant DA 01759. B. Marsha11~oodell was supported as a postdoctoral trainee under NIMH Grant MH 15773. Requests for reprints should be addressed to I. Gormezano, Department of Psychology, University of Iowa, Iowa City, Iowa 52242. D. D. Dorfman's constructive comments and critical reading of the manuscript are gratefully acknowledged. calibrated to yield, for each subject, 16 A/D counts for each millimeter of movement. Moreover, Our software system, FIRST, an adaptation of FORTH (Moore, 1974), is an interactive, high-level, dictionary-based language that provides a programming and control system whose very high processing speed, flexibility, and ease of programming far exceeds that e...

The extraction of mean amplitude from integrated electromyographic (IEMG) responses provides a valid but limited measure of muscle action potentials (MAPs). More comprehensive topographical analyses of IEMG responses based on frequency analyses are unsatisfactory since IEMG responses are aperiodic, and autoregressive procedures may be unsatisfactory since autocorrelations constitute an irreversible transformation of the original waveform, represent a substantial loss of information in contrast to the original waveform, and harbor little apparent relationship to MAPs. In a Theoretical Investigation, a mathematical procedure is developed to quantify topographical features of both the amplitude and temporal dimensions of the IEMG response. Procedures for extracting these parameters and the relationship between each and the recruitment of MAPs are illustrated. In a Validation Study, surface electromyograms are recorded from the preferred forearm under various conditions of mild isometric forearm contraction. Results support the viability, reproducibility, and validity of the topographical analysis.

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Elicitation of responses by electrical brain stimulation (EBS) was related to the synaptic distance of the target nucleus from the accessory abducens. Specifically, responses to EBS in the spinal trigeminal nucleus (TRIG) and red nucleus (RN) increased as a positive function of stimulation parameters. Responding to EBS in the interpositus nucleus (IP) was lower, and responding to EBS in the inferior olive (IO) was negligible. EBS in the TRIG, IP, and RN nuclei was then paired with a tone conditioned stimulus (CS). The CS modified responses for EBS in RN and TRIG but not IP. CS-EBS pairings yielded conditioned response (CR) acquisition, in which Groups TRIG, IP, and RN reached asymptotes of 90%, 70%, and 43% CRs, respectively. Thus, contrary to previous findings, EBS in the efferent pathway can support CR acquisition. The results are discussed with respect to the role of projections from the RN to the cerebellar cortex and the TRIG nucleus.

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