Ejaculate disruption in two species of voles (Microtus): on the PEI matching law.

We permitted male prairie and montane voles (Microtus ochrogaster and M. montanus) five thrusts, without ejaculation, with a female at variable times after a 1st male ejaculated. In both prairie and montane voles, there were fewer sperm, in relation to control conditions, in the female's tract 1 hr after ejaculation if the female received thrusts immediately or 15 min after the ejaculate. There was no such effect after a 50-min delay. There was no significant decrease in litter production in prairie voles caused by thrusts delivered either immediately or after a 15-min delay. Sperm transport in these species is susceptible to disruption for a longer period than in deer mice or rats. The proposal that the postejaculatory interval protects a male from disrupting its own sperm transport (the PEI matching law) appears not to hold for these species.     

A method for examining short-term retention of haptic cues in monkeys

Tasks used to examine short-term memory (STM) in animals have almost exclusively required retention of visual cues. To determine if haptic information can be retained, three rhesus monkeys were trained to perform, using only haptic cues, a simultaneous (SMS) and a delayed matching-to-sample (DMS) task. On each trial, the monkeys felt and responded to a sample stimulus on a centrally located manipulandum. They were then presented two comparison stimuli located on both sides of the central manipulandum. A response matching the comparison stimulus with the sample stimulus was reinforced. In SMS a mean of 2,725 trials was required to reach a criterion of 90% correct. As in DMS performance for visual cues, in haptic DMS the monkeys were capable of above-chance responding at retention intervals of greater than 1 min. This haptic DMS task should be useful for testing STM models, for examining the physiological basis of STM, and for examining drug effects.     

Self-image disparity, repression-sensitization, and extraversion-introversion: a unitary dimension?

To determination (1) whether self-image disparity, repression-sensitization, and extraversion-introversion intercorrelated to a degree indicative of a unitary personality dimension and, (2) whether the interrelationships among these variables was accounted for by cognitive developmental variance, Byrne's Revised Repression-Sensitization Scale, Giedt and Downing's Extraversion-Introversion Scale, and two measures of self-image disparity were administered to 20 male college freshmen and 20 male seniors. All the correlations among the four measures were significant, but none correlated significantly with cognitive development, as measured by SATs. Factor analysis yielded a clearcut personality factor and a clearcut cognitive factor, indicating that the personality measures reflect a unitary dimension, even after cognitive developmental variance is extracted.     

Computer signal detection by monitoring auditory evoked potentials

A digital computer, using a simple decision algorithm, attempted to determine when an acoustical signal had been presented to a cat by monitoring the amplitude of the evoked potentials (EP) at brainstem auditory nuclei. The signal-to-noise level at threshold and the shape and range of the decision model “psychometric functions” were similar to those obtained from humans in the same task. In addition, the detection performance obeys Weber’s law, the mean amplitude of the EP increases monotmonically with signal level, the variance of the amplitude is independent of both signal and noise level, and both the mean latency and the variance of the latency of the peaks decrease with increasing signal level. These findings suggest that the synchronization in firing of a population of single units plays a part in determining the amplitude of the EP. Interaural effects in detection performance were found at the inferior colliculus and, to a lesser extent, at the superior olive.     

A device for rapid recording of positioning responses in two dimensions

A device for rapid recording of positioning responses is described. It utilizes an extremely simple, low-cost position transducer and two digital voltmeters or their equivalent. The device has the advantages of rapid, accurate measurement, reliability, ease of reading, and the potential for automatic recording of positional data in two dimensions.     

Dream symbolization in light of analytic and experiential thinking

This paper compares the analytic and experiential approaches to dreams in order to illuminate the intrinsic and necessary relationships between the two understandings. It describes how dream work reflects the bimodalness of symbolism, thought and ultimately human consciousness. An extended example of dream work reflecting both analytic and experiential modalities is presented.     

Rational social and political polarization

Philosophical Studies - Public discussions of political and social issues are often characterized by deep and persistent polarization. In social psychology, it’s standard to treat belief...