General Learned Irrelevance and Its Prevention

Random presentation of a tone and an electric shock to rats interfered with subsequent acquisition of a light–shock association. This interference, or “general learned irrelevance” phenomenon, however, could be prevented by prior learning of a positive relationship between the tone and the shock or that between a noise and the shock. These results strongly support the ideas that animals learn irrelevant stimulus relationships and that prior experience of stimulus relevance prevents learning irrelevance. The similarity of this observed prevention effect to an immunization effect on learned helplessness phenomena is discussed.     

Size-distance paradox with accommodative micropsia

Two experiments tested the hypothesis that the paradoxical relative distance judgment associated with the size-distance paradox is due to the visual system’s assuming equal linear size and perceiving a smaller angular size for the closer stimulus equal in visual angle. In Experiment I, two different sized coins were presented successively, and 16 Ss were asked to give ordinal judgments of apparent distance and apparent size. When the two coins depicted the same figures, the closer stimulus was judged to be farther and smaller, more frequently, than when two coins depicted different figures. In Experiment II, 48 Ss were asked to give ratio judgments of apparent distance, apparent linear size, and apparent angular size for two stimuli which were presented successively. When the stimuli were of equal shape, the mean ratios of the far stimulus to the near stimulus were smaller for the apparent distance but larger for the apparent linear size and angular size than when the stimuli were of different shape. The obtained distance judgments were consistent with the hypothesis but the obtained judgments of linear size and angular size were not.     

Apparent movement and change in perceived location of a simulus produced by a change in accommodative vergence

Using a psychophysical method of adjustment, 175 Ss, ranging in age from 3 to 20 years, made four adjustments each of a luminous line to subjective vertical, horizontal, and 45-deg tilts in the dark. There were no significant differences in mean errors of adjustment to the vertical and horizontal over the ages tested. There were significant differences in intra-S variability of adjustment to the horizontal and vertical, with the greatest improvement occurring before age 10. Older children and adults produced significantly larger mean errors of adjustment to the 45-deg tilt than did the younger children; but the variability of settings by younger children was very high, indicating that they did not discriminate the 45-deg tilt more accurately than the older groups. The intra-S variability at all ages showed that adjustment was more accurate to the horizontal and vertical than to the 45-deg tilt.     

Extraction of linguistically relevant pragmatic contrast through language learning

This study explores whether pragmatic contrast that is not expressed as relevant in the subjects' native language is extracted through language learning. Miniature artificial languages were used. In Experiment 1, a contrast was created such that four persons appeared together in each situation, with three persons performing the same activities and the fourth one performing a different target activity. Under this presentation condition pragmatic contrast was shown to be rather easily extracted. In Experiments 2 and 3, a single person appeared in each situation and contrast was created serially by changing the position in which the person performing the target activity was placed. Under these presentation conditions sufficient evidence for the extraction of pragmatic contrast was not found. Experiment 2 also examined the effect of different experience of instances on the extraction of pragmatic contrast. Results showed that although different experience did not produce a differential effect as expected, a definite conclusion was not drawn for a low level of performance. It was formulated that the two presentation conditions differed in the degree of transparency for a mapping relation between the linguistic structure and the pragmatic contrast. Implications of the findings were suggested in relation to a natural learning situation.Deep gratitude is due to Professor D. D. Steinberg for his reading of an earlier version of this paper.     

The lost direction in binocular vision: the neglected signs posted by Wells, Towne, and LeConte

Studies of vision have informed theories first in philosophy and then in psychology. Over the centuries, an increasing number of phenomena have been enlisted to refute or reinforce particular theories. Nowhere has this been more evident than in binocular vision. How we see a single world with two eyes is one of the oldest and most consistently studied topics in vision research. It has been discussed at least since the time of Aristotle and it has been examined experimentally since the second century, when Ptolemy defined lines of visual correspondence for the two eyes. Prior to Wheatstone's invention of the stereoscope in the 1830s, binocular vision had been studied in terms of visual directions. The stereoscope established distance (or depth) as well as direction as dimensions of binocular vision. Subsequently, depth rather than direction has been the principal concern of students of vision, and texts in English devoted to analyses of direction rather than depth have been neglected. We examine the experiments on binocular visual direction conducted by Wells before Wheatstone, and by Towne and LeConte after him, and discuss the reasons for their neglect.     

Contextual interference in implicit and explicit motor learning

The purposes of this study were to examine the contextual interference effect in implicit learning and to compare implicit and explicit learning. Thirty-two participants performed a pursuit-tracking task for 60 acquisition and ten retention trials. The middle segment of target pathways had only two patterns whereas other segments had random patterns. A combination of awareness and practice order for the middle segment created four acquisition conditions: implicit-blocked, implicit-serial, explicit-blocked and explicit-serial. A questionnaire and a recognition test revealed that implicit groups were unaware of the repetition. Results showed no contextual interference effect in either implicit or explicit learning. Acquisition and retention performances were better for the middle segment than the other segments regardless of awareness. No difference between the implicit and explicit groups was found, suggesting that the implicit learning condition led to learning equivalent to the explicit learning condition.     

Encoding richness of self-generated elaboration and spacing effects on incidental memory

The present study investigated encoding variability in self-generated elaboration on incidental memory as a function of the type of presentation which was either massed or spaced. The subjects generated different answers to a "why" question for the first and the second presentations of a target sentence in a self-generated elaboration condition. In an experimenter-provided elaboration condition they then rated the appropriateness of the different answers provided by the experimenter for the first and second presentations. This procedure was followed by two free recall tests, one of which was immediate and the other delayed. A self-generated elaboration effect was observed in both the spaced and the massed presentations. These results indicated that the self-generated elaboration effect was facilitated, even in the massed presentation because the different answers to the first and the second presentations led to a richer encoding of each target.     

Kanizsa's shrinkage illusion produced by a misapplied 3-D corrective mechanism

In order to include the monocular areas from the left and the right eye in the cyclopean view, the visual system displaces the occluded elements which would result in a horizontal elongation of the shape but does not occur thanks to a correction mechanism which preserves the shape. We hypothesised that this mechanism causes Kanizsa's amodal shrinkage illusion (the apparent elongation of a partially occluded square) when it is incorrectly applied by the visual system to a two-dimensional stimulus. Four experiments tested this hypothesis: (i) one-eyed observers were less susceptible to the illusion than people with normal binocular vision because, for them, the correction for shape is unnecessary; (ii) the illusion was stronger with binocular than with monocular vision since binocularity induces the visual system to correct for the shape distortion; (iii) the illusion diminished when the stimulus was rotated 90 degrees given that displacement and compression are not required for vertical occlusion; (iv) the magnitude of the illusion was a function of the width of the occluder because, as previous research has shown, the edges of a partially occluded square are less displaced the farther they are from the edges of the occluder. The data from the four experiments support our hypothesis even though no condition was able to eliminate the illusion; other possible causes are discussed.     

Involvement of IP3 receptors in LTP and LTD induction in guinea pig hippocampal CA1 neurons

The role of inositol 1, 4, 5-trisphosphate receptors (IP3Rs) in long-term potentiation (LTP) and long-term depression (LTD) was studied in CA1 neurons in guinea pig hippocampal slices. In standard solution, short tetanic stimulation consisting of 15 pulses at 100 Hz induced LTP, while three short trains of low-frequency stimulation (LFS; 200 pulses at 1 Hz) at 18-min intervals or one long train of LFS (1000 pulses at 1 Hz) induced stable LTD in both the slope of the field EPSP (S-EPSP) and the amplitude of the population spike (A-PS). Bath application of 2-aminoethoxydiphenyl borate (2-APB), an IP3R antagonist, or of alpha-methyl-4-carboxyphenylglycine (MCPG), a wide-spectrum metabotropic glutamate receptor antagonist, during weak tetanic stimulation significantly increased the magnitude of the LTP in both the S-EPSP and A-PS. Three short trains of LFS or one long train of LFS delivered in the presence of 2-APB or MCPG did not induce LTD, but elicited LTP. Based on these results, we conclude that, in hippocampal CA1 neurons, IP3Rs play an important role in synaptic plasticity by attenuating LTP and facilitating LTD.