Coherent probability from incoherent judgment

People often have knowledge about the chances of events but are unable to express their knowledge in the form of coherent probabilities. This study proposed to correct incoherent judgment via an optimization procedure that seeks the (coherent) probability distribution nearest to a judge's estimates of chance. This method was applied to the chances of simple and complex meteorological events, as estimated by college undergraduates. No judge responded coherently, but the optimization method found close (coherent) approximations to their estimates. Moreover, the approximations were reliably more accurate than the original estimates, as measured by the quadratic scoring rule. Methods for correcting incoherence facilitate the analysis of expected utility and allow human judgment to be more easily exploited in the construction of expert systems.     

A gray seal's (Halichoerus grypus) responses to experimenter-given pointing and directional cues

A gray seal (Halichoerus grypus) was trained to touch a target on its left or right by responding to pointing signals. The authors then tested whether the seal would be able to generalize spontaneously to altered signals. It responded correctly to center pointing and head turning, center upper body turning, and off-center pointing but not to head turning and eye movements alone. The seal also responded correctly to brief ipsilateral and contralateral points from center and lateral positions. Pointing gestures did not cause the seal to select an object placed centrally behind it. Like many animals in similar studies, this gray seal probably did not understand the referential character of these gestures but rather used signal generalization and experience from initial operant conditioning to solve these tasks.     

Eidetic-like imagery in hypnosis: rare but there

The production of eidetic-like imagery during hypnosis in subjects with high but not low hypnotizability was supported in three separate experiments using nonfakable stereograms (Julesz, 1971; Gummerman, Gray, & Wilson, 1972). In Experiment 1, 6 (25%) of 24 stringently chosen, high hypnotizables were able to perceive one of the superimposed stereograms (presented monocularly) during conditions of standard hypnosis or hypnotic age regression, or under both conditions, but not during waking. In Experiments 2 and 3, low and high hypnotizables were presented stereograms in an alternating, monocular fashion (one-half to each eye). In Experiment 2, 10% of the high hypnotizables perceived one or more stereograms in hypnosis or age regression, but not during waking. In Experiment 3, none of the 17 low hypnotizables reported correct stereograms, but 6 of the 23 high hypnotizables (26%) did. Relationships between imagery performance and visuo-spatial abilities were investigated. Results support the general hypothesis that hypnosis enhances imaginal processing of information to be remembered that is a literal or untransformed representation.     

Relationships between physical exercise and cognitive abilities in older adults

We investigated relationships between physical exercise and the cognitive abilities of older adults. We hypothesized that the performance of vigorous exercisers would be superior to that of sedentary individuals on measures of reasoning, working memory, and reaction time. We gave a series of cognitive tasks to 62 older men and women who exercised vigorously and 62 sedentary men and women. Multivariate and univariate analyses of variance, with age and education as covariates, indicated that the performance of the exercisers was significantly better on measures of reasoning, working memory, and reaction time. Between-group differences persisted when vocabulary, on which the performance of exercisers was superior, was used as a third covariate. Subsequent analyses showed that neither self-rated health, medical conditions, nor medications contributed to the differences between exercise groups. Results suggest that the possible contribution of physical exercise to individual differences in cognition among older adults should be further investigated.     

Shape constancy and slant perception at birth

Two experiments are described the object of which was to investigate whether perception of shape at birth is determined solely by proximal (retinal) stimulation, or whether newborn babies have the ability to perceive objective, real shape across changes in slant. In experiment 1 looking at (ie preference for) one stimulus, a square, when paired with either of two trapeziums, was found to change in a consistent manner with changes in slant, indicating that these changes in stimulation are detected and can cause considerable changes in looking behaviour. In experiment 2 newborns were desensitized to changes in slant during familiarization trials, and subsequently strongly preferred a different shape to the familiarized shape in a new orientation. This suggests that the real shape had been perceived as invariant across the retinal changes caused by the changes in slant, and further suggests that shape constancy is an organizing feature of perception which is present at birth.     

Age-related differences and similarities in dual-task interference

Differences between younger adults (mean age, 20.7 years) and older adults (mean age, 72.7 years) in dual-task performance were examined in 7 experiments in which the overlap between 2 simple tasks was systematically varied. The results were better fit by a task-switching model in which age was assumed to produce generalized slowing than by a shared-capacity model in which age was assumed to reduce processing resources. The functional architecture of task processing appears the same in younger and older adults. There was no evidence for a specific impairment in the ability of older adults to manage simultaneous tasks. There was evidence for both input and output interference, which may be greater in older adults.     

Left Syringeal Dominance in Testosterone-Treated Female Canaries

Male canaries (Serinus canaria) produce most of their song syllable types on the left side of the syrinx, the two-sided vocal organ. Female canaries treated with testosterone propionate begin to sing in a male fashion, a behavior seldom seen in untreated females. To learn whether syringeal dominance occurs in testosterone-treated female canaries, we deactivated either the right or the left side of the syrinx by severing the tracheosyringeal nerve on that side. Recordings of the birds’ songs were made before and after the nerve cut, and song analysis was based upon visual comparisons of sound spectrograms. Pre- and post-operative syllable types were identified by their frequency structures and repetition rates. Six of eight birds displayed clear left dominance as assessed by nerve cuts; therefore, we concluded that most, but not all, female canaries generate the majority of their syllable types with the left syrinx.