Canadian journal of psychology最新文献

In this study the recall of autobiographical and public events across the lifespan was examined in a sample of middle-aged and older-aged adults. The tasks were modified versions of one first introduced by Galton (1879), and they required subjects to recall events from specific time periods across their entire lifespan. The four tasks differed in the nature of the episodes requested (autobiographical or public) and whether recall was word-cued or non-word-cued. Verification of public events was assessed archivally, and autobiographical events were verified by a sample of relatives for a subgroup of the subjects and reported events. The results indicated that memory for public events decreases with increased age of the subject, but this effect is not generally found for the recall of autobiographical events. The older-aged subjects were able to recall an equal number of autobiographical episodes from all life segments, whereas recall of news events tended to decrease with remoteness of the episode. These data are contrary to those models that posit general memory loss as a function of age or of remoteness of the events.

The objective of the present study was to test the hypothesis that the age at which a second language is acquired influences the pattern of cerebral lateralization associated with that language. Subjects who differed in terms of the age at which they had acquired their second language (English or French) were tested on a concurrent task paradigm involving motor and language performance. Hemispheric processing was inferred from the pattern of lateralized and generalized interference between the tasks. No support was found for the age-of-acquisition hypothesis. Instead, the data indicated a language-specific effect. Regardless of age of acquisition and of whether the first language was English or French, bilingual subjects showed lateralized interference effects consistent with left-hemisphere processing when reading in English and translating from French into English, but no lateralized interference when reading in French and translating from English into French. Whether this effect reflects characteristics of the two languages or the influence of social factors in subject-experimenter interaction is considered.

Over the past 30 years, numerous studies have reported left/right asymmetries in visual field performance, with performance generally superior in the right visual field for verbal tasks and in the left visual field for spatial tasks. These asymmetries parallel those found in neurological studies of hemispheric specialization. Consequently, many investigators have concluded that visual hemifield differences are primarily a reflection of the functional differences between the two cerebral hemispheres. However, alternative explanations proposing that visual field effects are dependent on other factors such as inadequate fixation, eye movements during presentation, postexposural scanning, and attentional biases have been offered. The potential impact of each of these factors on visual field differences are reviewed and discussed. Evidence is provided suggesting that attention and hemispheric functional differences interact to produce the magnitude and direction of visual field differences.

Contrary to commonly held convictions, there is no clear association between brain size and body parameters in humans. Within sexes, once age and health status are controlled for, there is no significant association between brain size and body height for females. For males, body height accounts for no more than .04% of the variance in brain size. The relation between brain weight and body weight is even less clearly defined. Nevertheless, there are large and significant differences in brain size between the sexes. If no adequate body parameters can be found that scale to brain size within the sexes, the marked dimorphism between males and females makes it even more difficult to find a common set of parameters that allow evaluation of brain size differences between sexes. Within and across sexes, there is no convincing link between a limited measure of behavioural capacity (IQ) and brain size. This leads to the more general question: Why would one expect such a link, and, if it is not found, what does this mean in the context of general theories of cortical function?

Handedness among architects was determined by mail survey. Contrary to previous reports, no evidence was found of an excess of left-handers among a sample of 236 fully qualified male architects and 78 male architectural students. A second study examined whether the use of mail surveys systematically biases the returns of handedness questionnaires. For this, questionnaires were sent to 1,017 university students. No evidence was found for a bias amongst those who did and did not reply to the initial questionnaire. These results strengthen the findings of the first study.

Using all four combinations of hand and foot, adult stutterers and nonstutterers performed a unimanual sequential finger tapping task together with a stimulus-contingent foot responding task. The two groups were similar in that both demonstrated more dual-task interference when using the ipsilateral than contralateral limb pairs. Contrary to a prediction based on a hypothesis that attributes stuttering to neural interference due to an ungated or unregulated activity flow between the hemispheres, stutterers did not show more interference than nonstutterers when using the contralateral limb pairs. The groups did differ, however, in terms of finger tapping interference associated with right- versus left-foot concurrent task responding. Nonstutterers showed more interference when using the left than right foot. This was interpreted in terms of the attentional demands that the foot responding task placed on a system with an inherent left-hemisphere attentional bias. The lack of a reliable difference in stutterers with respect to interference by the two feet is consistent with indications from other research that stutterers have a relatively labile system of hemispheric attention or activation. The results of the study are placed into the context of a general model of the brain mechanisms associated with stuttering.

An important part of Benbow's (1988) assertion that sex differences in mathematical ability are primarily due to biological factors is the link between a trait that is assumed to reflect differences in brain organization (left-handedness) and mathematical giftedness. It is shown that the link between mathematical giftedness and an increased prevalence of left-handedness is not convincing. However, Benbow's (1986) data do show a convincing link between strong right-handedness and the lack of mathematical giftedness, in agreement with Annett and Manning's (1990a, 1990b) recent work.

The concept of invariant relative timing has typically been associated with the concept of a generalized motor programme. The present study approaches the phenomenon of invariant relative timing from the perspective of learning. The underlying question of concern for this study was, "What is learned." The specific question was whether relative timing is one of the essential properties of movement that is learned during skill acquisition. In the present experiment, subjects were given extensive practice in learning to track and reproduce a criterion waveform using a joystick control for their response. In order to test whether subjects learn the relative timing of a movement, they were transferred to tracking waveforms that were identical to the criterion in terms of relative timing, but different in terms of absolute timing. Measurements were taken on all waveforms in two conditions: (a) in a pursuit tracking condition where subjects were temporally constrained by the stimulus, and (b) in a reproduction condition where subjects' timing was not constrained. The outcome from both conditions gives support to the idea that humans learn invariant relative timing during the acquisition of a motor skill.

We recently found (Schneider, Moraglia, & Jepson, 1989) that the contrast threshold for the detection of a visual signal in a noisy background can be considerably lower when binocular cues are available then when monocular cues only are present. Here, we investigated the occurrence of binocular unmasking with vertical interocular disparities. Subjects reported about the presence of Gabor signals in fields of two-dimensional broadband Gaussian noise surrounded by a frame of uniform noise. They saw these stimuli through a stereoscope; in all cases, the right-eye noise field was vertically displaced relative to the left one in either an upward or a downward direction, by up to 67.6'. In one condition, the right-eye signal was displaced by an amount equal to that of the noise, so that no opportunities for binocular unmasking existed; in the other, it appeared in exactly corresponding locations in the two fields--here, binocular disparities could be used to unmask the signal. Enhanced signal detectability, by up to 12.7 dB, was observed in the latter case for both directions of displacement, but only for displacements of 13.52' and only when the signal's orientation was horizontal. We argue that these effects result from the summation of monocular inputs carried out by linear binocular mechanisms.

In an earlier paper, we reported that subjects have great difficulty in finding alternative construals of their own mental images. In the present paper, we examine how subjects can nonetheless learn from their mental images. We argue that mental images, like percepts, are meaningful depictions. As such, mental images do depict appearance but are also inherently understood in a certain way, and this understanding influences the phenomenal appearance of the represented form. This, in turn, governs what the form will be seen to resemble and what the form is likely to call from memory. We report four experiments in support of this view. In each experiment, subjects are briefly shown outline shapes and asked to form a mental image of each shape. Subjects are then asked what familiar form the imaged shape resembles. Subjects routinely find target shapes in their images when the target is compatible both with the imaged geometry and with how that geometry is organized and understood. When the sought-for target is compatible with image geometry but not with how the image is understood, subjects reliably fail to find the target shape in their images.