Goal-Directed Aiming: Correcting a Force-Specification Error With the Right and Left Hands

In 2 experiments, the authors examined manual aiming asymmetries as well as the ability of participants to adjust their aiming trajectories following an unexpected change to the inertial resistance to movement. In Experiment 1, participants (N = 11) were able to rapidly adjust their movement trajectories to conform to the new movement requirements. They were faster and more consistent when aiming with their right hand than with their left hand, regardless of whether or not the movement was perturbed. In Experiment 2, participants' (N = 11) vision of the hand was manipulated so that the role of visual feedback in the corrective process could be examined. Vision had an impact not only on performance but also on the characteristics of the movement trajectories. Manual asymmetries in aiming were associated with a right hand superiority during the final corrective stages of the movement.     

Timing the Selection of Information During Rhythmic Catching

Catching a ball requires that information be available close to the catch but early enough for prospective or corrective control. In the present experiment, 6 participants were asked to throw and catch a ball continuously for 1 min while wearing liquid-crystal goggles that restricted viewing to specific amounts of time at specific intervals. Participants were free to select the information by varying the frequency and phasing of throwing relative to the goggles. Video analysis revealed that they elected a frequency of throwing that matched the goggle frequency and chose to view the ball at or around its zenith. Earlier portions of the ball's trajectory were viewed as the goggle frequency increased. Despite variations in the viewing location, participants elected to view the ball on average 365 ms before the catch. Analysis of the hand's trajectory further revealed that the time interval (M = 82 ms) between the ball's zenith and the initiation of the final motion of the hand toward the catch did not vary as a function of the frequency of throwing. The authors conclude that the timing constraints imposed by the hand's movement are the basis for the selection of information for catching.     

The effect of subject-generated and experimentersupplied code words on the phonetic mnemonic system

The hypothesis tested proposed that subjects using the phonetic mnemonic system who were supplied code words by the experimenter would recall more numbers than either subjects generating their own code words or a control group. In Experiment 1,36 undergraduate subjects serving in a 3 × (3) mixed-factorial design confirmed the hypothesis, but the possibility existed that the superiority of the experimenter-supplied group was attributable to the failure of the subject-generated group to devise a complete set of code words. In Experiment 2 a new group of 12 self-generated subjects was tested with a modified procedure designed to maximize number of correct code words. However, the experimenter-supplied group recalled significantly more numbers than this group, too. In Experiment 3 the possibility was tested that the superiority of the experimenter-supplied subjects was an artifact based on insufficient training in the phonetic method of subjects creating code words. Accordingly, all 28 subjects received extended training before recall of a subject-generated group was tested against that of an experimenter-supplied group in a 2 × (2) factorial design. Once again the experimentersupplied group recalled significantly more numbers, confirming the hypothesis. These results represent an exception to the general finding that subject-generated mnemonics are superior to those supplied by the experimenter. The data suggest that the relative efficacy of the two sources interacts with the difficulty of the mnemonic.     

Perception of visual letter strings in a case of left neglect: Manipulation of the word form

Patients with lesions in the right parietal lobe neglect the left side of nonwords much more than the left side of words. This has been interpreted in terms of a more automatic process in reading words. The case of a patient with left visual neglect after a vascular right parietooccipital lesion is presented. He showed the phenomenon of a word superiority effect over nonword in reading at the beginning in a clinical test with static cards; 6 months later, after some recovery, the same phenomenon could be demonstrated only with tachistoscopic presentation, and it occurred even inside the good right visual hemifield. The word form of visually presented stimuli was manipulated, showing that there was a striking effect particularly when spacing the letters of words in a task that requires naming the stimulus. The patient's performance is interpreted in terms of an attentional deficit occurring at an early level of spatial information processing.     

STRESS, SOCIAL SUPPORT, AND HEALTH IN MARRIED PROFESSIONAL WOMEN WITH SMALL CHILDREN

Two hundred married professional women with small children were surveyed to investigate what types of occupational and role-conflict stresses are associated with physical and depressive symptoms, and whether social support could protect individuals from the negative health effects of stress. Six stress indices predicted physical and depressive symptoms, both Concurrently and 1 year later. These stresses reflected perceptions of lack of authority and influence on the job, sex discrimination, a heavy work load, work imposing on relaxation, family imposing on relaxation, and overall suffering from role conflict. Social support yielded no stress-buffering effects.     

Spatial and fixation conditions affecting the temporal course of changes in perceived relative distance

The results of two experiments are reported in which the change over time in the perceived depth location of a monocular, luminous test object with respect to two binocular luminous stimuli located at different distances was measured. It was found that: 1) The test object receded perceptually in depth over time achieving a stable location in space after 4 min of viewing. 2) The initial perceived location in depth of the test object depended upon which of the two binocular objects was fixated. When the farther binocular object was fixated the test object appeared further away than when the nearer one was fixated. 3) The size of the further binocular object also affected the initial perceived location of the test object. When it was larger, the test object appeared further away than when it was smaller. 4) There was an interaction between the binocular object fixated upon and the lateral separation between it and the test object: the smaller the separation, the greater the fixation effect.These results were accounted for in terms of the equidistance tendency, the depth adjacency principle, and a possible attentional factor. Taken together the results indicate that while reduced viewing conditions reduce the available stimulus information, they do not reduce the organizational options of the visual system.     

Some conditions for the dissociation of consummatory and instrumental behavior in rats

To investigate whether consummatory and instrumental behavior depend upon different motivational factors, rats were trained to press a bar for saccharin solution, then given various treatments designed to reduce the palatability of saccharin, and finally tested for bar-pressing in extinction and for free intake of saccharin. Prefeeding with dextrose, prefeeding with saccharin, and association of saccharin with injections of lithium chloride all reduced intake of saccharin compared to control treatments, but only prefeeding with dextrose also reduced barpressing in extinction. Thus, performance of an instrumental response may depend upon need for food rather than appetite for it.     

Long-lasting aftereffect of brief prism exposure

The aftereffect of 15 min of active adaptation to wedge prism displacement was shown to persist for as long as 2 weeks.