Canadian journal of psychology最新文献

Sixty-six subjects learned responses to four ellipses (eccentrically 0.52) which varied orthogonally in area (two large: 994 mm2; two small: 671 mm2) and orientation (two with major axis vertical, two with major axis horizontal). Correct responses were contingent on either the area or the orientation of the ellipses. After learning the correct responses, subjects recalled the ellipses by drawing them. Recall was either immediately, 1 day, or 2 weeks after learning the responses. The recall drawings were measured for area and for orientation (ratio of the length of the vertical to the horizontal axis). Differences among the recall drawings increased on the dimension (area or orientation) which was associated with correct responses during the learning task. The differences on the associated dimension were large when recall was tested immediately after the response learning task, small when recall was tested 1 day after learning, and large again when recall was tested 2 weeks after learning the responses. This experiment eliminated one potential source of uncontrolled variability in earlier results. The results are consistent with previous experiments and suggest an active two-phase memory consolidation process extended over time.

Experiments examined grammatical judgement, and error-identification deficits in relation to expressive language skills and to morphemic errors in writing. Language-disabled subjects did not differ from language-matched controls on judgement, revision, or error identification. Age-matched controls represented more morphemes in elicited writing than either of the other groups, which were equivalent. However, in spontaneous writing, language-disabled subjects made more frequent morphemic errors than age-matched controls, but language-matched subjects did not differ from either group. Proficiency relative to academic experience and oral language status and to remedial implications are discussed.

Target-aiming studies in which premovement visual information is manipulated suggest that when vision is occluded, a brief visual representation of the target environment may be used to guide movement. The purpose of this work was to determine if the internal representation contains information about the whole movement environment or just specific information about the position of a single target goal. Two experiments were conducted in which we manipulated both target uncertainty and the visual information available before and during a target-aiming movement. Radial error differences between visual conditions and the independence of the vision and uncertainty manipulations support the hypothesis that subjects form a representation of the overall movement environment.

Previous work by Porac, Coren, and Searleman (1986) looked at overt attempts to change hand preference from the left to the right side. We extended this research by studying individuals who shifted their handedness from the left to the right side as well as a group who attempted a shift in the opposite direction (right to left). Comparisons of the two shift attempts revealed that the timing, method, and agent of change differed significantly for right versus left shifts. More right than left shifts were successful. Overall, most shift attempts were rated as unsuccessful because they did not result in a handedness classification consistent with the direction of the shift. Individuals classified as successful shifters, whether in the right or left direction, displayed a more ambihanded behavioural pattern than either unsuccessful shifters or the no shift control group. Evidence suggested that left-shift attempts were promoted by original ambihanded tendencies but that ambihandedness in successful right shifts stemmed from the partial success of the switch attempt.

Two carefully matched groups of normal old people living in institutions or in the community were administered a neuropsychological cognitive test battery. In general, the institutionalized group performed worse than the community group. Discriminant function analysis identified a subgroup of high-functioning institutionalized subjects whose performance more closely resembled that of the community group than the remainder of the institutionalized group. Differences between the various groups were not due to differences in IQ, age, health, or other controlled variables. The critical tests that differentiated the groups were sensitive to impaired function in frontal and medial-temporal lobe brain regions. The results suggest a complex interaction involving effects of age and environmental factors on brain function and cognition.

Three studies investigate the role of size information in haptic classification of custom-made planar objects when size covaries with hardness, texture, or planar contour. The haptic exploratory procedure (Lederman & Klatzky, 1987) associated with size extraction is also sufficient for encoding shape, which should promote their integration. Experiment 1 showed substantial facilitation of classification by redundant size and shape cues, indicating the coprocessing of size and shape. Experiments 2 and 3 used a withdrawal paradigm: Classification trials began with two redundant properties, and one was then held constant (withdrawn). Experiment 2 showed that when size and shape were redundant, withdrawal of either impaired responses, whereas when size was redundant with texture or hardness, only size withdrawal had an effect. Experiment 3 demonstrated that this size weighting was not restricted to a single procedure for exploration. Size appears to be highly weighted in haptic classification and potentially integrated with other properties having compatible methods of extraction.

An invisible displacement test was administered to cats in order to test the hypothesis that search behaviour in this species is influenced by their limited capacity for object permanence as well as by their previous experience with the environment. Experiment 1 compared three groups of cats in a five-choice hiding task in which the hiding places could be discriminated by their spatial positions. Two groups received a visible displacement training before the invisible displacement test and one group did not. Experiment 2 compared two groups of trained subjects in the same task, but the hiding places could be discriminated by spatial and visual cues. The results confirmed that cats are unable to solve problems with invisible displacements. The visible displacement training improved their performance, but was not sufficient to make them succeed. Experience with the hiding potential of the covers also gives more persistence to search behaviour. Finally, the distribution of search attempts is not determined by the proximity to the target and is influenced only partially by the subjects' previous experience. Like Stage 5 infants, cats rely mainly on their immediate perception. They search for an object in the last location they have seen it disappear or under the nearest cover from this location.

Early naturalists explained field observations of social influences on animal learning in terms of spoken language, deliberate tuition of one animal by another, or intentional imitation. During the first half of the present century, experimental psychologists analyzed instances of social learning by animals in laboratory tasks as special cases of operant or classical conditioning. Neither of these traditional approaches provided much insight into the complex processes that often support animal social learning. By combining ethological focus on social learning as it occurs in natural habitat with analytical techniques developed in the psychological laboratory, contemporary researchers have made considerable progress in describing the many ways in which social interactions influence behavioural development in animals. The author's investigations of social influences on food selection by Norway rats provide one example of such an ethopsychological approach to the study of animal social learning.

The perceptual grouping of a four-tone cycle was studied as a function of differences in fundamental frequencies and the frequencies of spectral peaks. Each tone had a single formant and at least 13 harmonics. In Experiment 1 the formant was created by filtering a flat spectrum and in Experiment 2 by adding harmonics. Fundamental frequency was found to be capable of controlling grouping even when the spectra spanned exactly the same frequency range. Formant peak separation became more effective as the sharpness (amplitude of the peak relative to a spectral pedestal) increased. The effect of each type of acoustic difference depended on the task. Listeners could group the tones by either sort of difference but were also capable of resisting the disruptive effect of the other one. This was taken as evidence for the presence of a schema-based process of perceptual grouping and the relative weakness of primitive segregation.

Subjects judged the quality of rigid motion between pairs of three-dimensional drawings that differed by a rotation in depth. The figures were aligned with, and rotated around, either the vertical axis or an axis that was oblique with respect to the XYZ co-ordinate system. Rated quality of motion decreased with increasing angular disparity between the figures and with decreasing stimulus duration, regardless of whether the figures were vertical or oblique. The same subjects then participated in a mental rotation task using the same stimuli and angular disparities. An effect of principal axis emerged, such that subjects took longer to make decisions about obliquely aligned stimuli than about vertically aligned stimuli, especially if they received the oblique stimuli first. These data imply that perceived versus imagined movement through the same trajectory involves different processes. Whereas the apparent motion system performs its computations relatively automatically, the processes involved in mental rotation are more strategic in nature.