Proprioceptive impairment and postural orientation control in Parkinson's disease

Impairment of postural control is a common consequence of Parkinson’s disease (PD). Increasing evidences demonstrate that the pathophysiology of postural disorders in PD includes deficits in proprioceptive processing and integration. However, the nature of these deficits has not been thoroughly examined. We propose to establish a link between proprioceptive impairments and postural deficits in PD using two different experimental approaches manipulating proprioceptive information. In the first one, the subjects stood on a platform that tilted slowly with oscillatory angular movements in the frontal or sagittal planes. The amplitude and frequency of these movements were kept below the semicircular canal perception threshold. Subjects were asked to maintain vertical body posture with and without vision. The orientations of body segments were analyzed. In the second one, the postural control was tested using the tendon-vibration method, which is known to generate illusory movement sensations and postural reactions. Vibrations were applied to ankle muscles. The subject’s whole-body motor responses were analyzed from center of pressure displacements.In the first experiment, the parkinsonian patients (PP) were unable to maintain the vertical trunk orientation without vision. Their performances with vision improved, without fully reaching the level of control subjects (CS). In the second experiment, the postural reactions of the PP were similar to those of the CS at the beginning of the perturbation and increased drastically at the end of the perturbation’s period as compared to those of CS and could induce fall.These results will bring new concepts to the sensorimotor postural control, to the physiopathology of posture, equilibrium and falls in PD and to the role of basal ganglia pathways in proprioception integration. Nevertheless, in order to assess precisely the role played by sensorimotor integration deficits in postural impairments in PD, further studies establishing the links between clinical features and abnormalities are now required.     

A randomized clinical trial of online-biblio relationship education for expectant couples

This study evaluated the efficacy of a self-paced, Internet-based marriage and relationship skills education program ("Power of Two Online"). The program integrated an online intervention with print supplemental resources. New and expectant parents (n = 79) were randomly assigned to the 2-month intervention or placebo-control group. Assessments were conducted at baseline, 1-month, and 2-month follow-up intervals. Latent growth curve modeling was used to examine differences between conditions for marital satisfaction and conflict management. Participants who received the intervention reported trajectories of improved marital satisfaction and improved marital conflict management over time relative to controls. Implications for widespread dissemination of marriage and relationship education as a primary prevention tool are discussed.     

Reflections

The American Journal of Psychoanalysis -     

Visual-field differences in picture-word interference

Picture-word interference refers to the fact that if a picture (i.e., line drawing) is presented centrally with a word superimposed, picture-naming latency is longer than if that same picture is presented alone. This phenomenon, like the Stroop phenomenon, seems to be strongly influenced by the nature of the to-be-ignored word. That is, if the word names a member of the picture's semantic category additional interference is observed; however, if the word is replaced by a phonetically unviable consonant string interference is reduced. In the present experiments these effects were examined in the situation where the picture-word stimuli were presented unilaterally in either the left or right visual field. For right-visual-field presentations, phonetic and semantic factors both influenced performance just as in central presentations. As such, these results can be satisfactorily explained in terms of response competition processes. However, the results for the left-visual-field presentations were quite different. Although substantial interference was observed for all types of stimuli, the amount of interference was essentially independent of the linguistic nature of the superimposed letter string. These results do not appear to be explainable in terms of response competition processes. Instead, it is suggested that the best way to explain these results is in terms of the perceptual capabilities of the right hemisphere.     

Voice initiation and termination time in stuttering and nonstuttering children

Voice initiation time (VIT) and voice termination time (VTT) was measured in seven stuttering and eight nonstuttering children ranging in age from 4 yr, 6 mo to 6 yr, 10 mo. The experimental task was the production of /a/ in response to a 1000-Hz pure tone. Voice initiation time was defined as the period of time elapsing between the onset of the auditory stimulus and the onset of the subject's response of /a/, as displayed on an oscilloscope. Voice termination time was defined as the latency between termination of the stimulus tone and the point at which the oscilloscopic signal decreased by 90%. No statistically significant differences were found between the two groups with respect to either VIT or VTT. In addition, no apparent relationships were present among VIT, VTT, or stuttering severity.     

Perception of epistemic authority and attribution for its choice as a function of knowledge area and age

Three age groups of children and adolescents (9–10, 13–14, and 17–18 years old) were asked to indicate sources of information which serve as their epistemic authority in nine knowledge areas and to attribute reasons for their choices. In general, the results showed that children and adolescents differentiate among sources and select their epistemic authorities according to knowledge areas. It was found that while the perception of parents as epistemic authorities decreases with age, the perception of self increases considerably and becomes an important epistemic authority. In spite of the decrease in the perception of parents as epistemic authorities, they continue to be a significant source of knowledge. In addition, the perception of friends as epistemic authority increases relatively in social knowledge areas. With regard to causal explanation, it was found that children and adolescents use various reasons to explain their selection of epistemic authority. They differentiated among their reasons on the basis of the selected source. Knowledge-denotating source expertise was used as the most important reason. The selection of oneself was mainly attributed to familiarity, and helpfulness was used to explain the selection of mother, friend and father as epistemic authorities. Friend was also selected because of similarity. Age differences with regard to use of reasons reflected changes in source selection. This line of research sheds light on the interpersonal nature of knowledge acquisition.     

Types and frequency of errors in visual search

The experimental method allowed false-positive as well as false-negative errors to be measured during visual search. Data were collected from eight Ss on four target-set size conditions on each of 25 days in order to determine whether the finding that search rate is independent of target-set size after practice might be attributable to a systematic variation in total error rate with set size. Even after practice, these Ss continued to search significantly faster for a single target than for target sets which were composed of five or more characters. Further, the incidence of total errors was much lower than in those studies in which search rate had been found to be independent of set size (i.e., parallel processing), even though these latter studies considered only the occurrence of false-negative errors. Additional analysis strongly suggests that: (1) attainment of parallel processing and a highly accurate performance are incompatible, and (2) verbal instructions alone are not sufficient to control the accuracy levels.     

Sex role as a mediator of achievement in task performance

Participants in a test of the influence of sex role on performance in a masculine task were 96 male and female undergraduates. Subject sex, norm (challenging or not challenging), and experimenter (male, female, or no experimenter present) were varied in a 2×2×3 design. When challenged, subjects worked more successfully in the presence of a female than before a male or with no experimenter present. Results support the hypothesis that the arousal of achieving tendencies may depend in part on the importance and conspicuousness of role cues. Implications for industrial performance and for future research are discussed.The authors would like to acknowledge the thoughtful assistance of Barbara Moely and Beverly Jafek, who commented on earlier drafts of this paper.All correspondence should be sent to Dr. Laurie Larwood, Claremont Men's College Claremont, California 91711. Portions of this paper were presented at the meeting of the American Psychological Association, Chicago, August 1975.