Are rats short-sighted? Effects of stimulus distance and size on visual detection

Behavioural evidence concerning short-sightedness in rats is apparently conflicting: in some experiments rats have performed poorly with visual stimuli further than about 60 cm distant, while in others they have made efficient use of more distant cues, for example to find their way through mazes. However, in the experiments suggesting short-sightedness, the physical size of the stimuli was not varied, so that stimulus distance and visual angle were confounded. In the present experiment, therefore, the size and distance of the stimuli to be detected were varied independently. Over the range tested (30-160 cm), distance was found to produce relatively slight effects on the smallest detectable visual angle, and these tended to diminish with practice. Thus, no good evidence was found for short-sightedness in rats up to 160 cm, a finding consistent with current views of the structure and image-forming capacities of the rat's eye. The smallest detectable targets were, however, surprisingly large in view of the rat's visual acuity (which is about 1c/deg): at the distances tested, animals required considerable training to run reliably to targets subtending less than 5-10° of visual angle. Difficulties in responding to stationary stimuli of this size are likely to restrict severely the use that rats make of vision both in the laboratory and in their natural surroundings.     

Student Response to Three Types of Orientation Programs

A high proportion of positive responses was obtained from students who participated in three different types of pre-college orientation programs. Small group approaches consistently elicited more favorable responses than assemblies or large groups. Greater faculty involvement resulted in participants' noting an increased academic emphasis. Participants believed they had benefited in some way from programs which varied considerably as to length, activities, organization, and purposes.     

The Systematic Measurement of French and Raven's Bases of Social Power in Workgroups

A typology of five bases of social power developed by French and Raven (1959) has been used to study small-group behavior in field settings by various researchers but interpretation of these data is limited by several methodological shortcomings. This study describes the development and testing of questionnaire measures for the Legitimate, Expert, Referent, Reward, and Coercive bases of social power and attempts to correct some of the scale format confounds that have affected previous empirical efforts. Analyses of Likert-scaled responses from the 23-item questionnaire show for the first time that these five constructs are factorially identifiable and orthogonal. Scale responses are shown to accurately reflect hierarchical status differences in an organization and to correlate significantly with such common leader behaviors as Initiation of Structure and Consideration.     

Recovery of Locomotion in Monkeys With Spinal Cord Lesions

This study reanalyzes kinematically (via film) the pre- and postoperative locomotor behavior of 4 of the 10 monkeys with partial spinal cord lesions (T8) briefly described by Eidelberg, Walden, and Nguyen (1981). The behavior of the remaining 6 monkeys is qualitatively described. The analysis reveals that 5 of the animals initially exhibited unilateral hind limb stepping. Hind and forelimb cycle durations often differed postoperatively; the hind limbs commonly showed increased values, whereas forelimb cycle durations were reduced: ipsilateral interlimb phase values were usually inconsistent. A review of prior studies of primate spinal cord lesions indicates that sparing of the ventrolateral quadrant may not be essential for locomotor recovery (cf. Eidelberg, Walden, & Nguyen, 1981). Furthermore, this review as well as the kinematic analysis indicates that primates with very significant spinal lesions can stilI exhibit locomotor movements. Thus, although the primate's spinal cord seems less able than other mammals' to readily organize locomotor movements (Eidelberg, Walden, & Nguyen, 1981), the total absence of stepping in primates with completely transected cords is unexpected and warrants further research.     

Dimensions of affective experience in three age groups.

The dimensions by which adults of differing ages experience emotion were studied by self-administering questionnaires administered to older adults (n = 828) recruited from Elderhostel programs, middle-aged (ages 30-59) children of Elderhostel attenders (n = 231), and young adult (ages 18-29) subjects recruited from college classes or through Elderhostel participants (n = 207). Elders were higher in emotional control, mood stability, and emotional maturity through moderation and leveling of positive affect and lower in surgency, psychophysiological responsiveness, and sensation seeking. These findings are consistent with the hypothesized increase in self-regulatory capacity with age. These cross-sectional differences cannot, however, be distinguished from cohort-related explanations; they require considerable replication across different types of subjects and further characterization of the dimensions in terms of their functions for self-regulation.     

HIV counselling in the national blood transfusion service

The problems caused for the NBTS by the advent of HIV are reviewed, with particular reference to the impact on blood donor numbers, the strategies adopted to minimise the risk of HIV infection through blood transfusion, and the counselling dilemmas faced by the Service in the setting of the blood donor clinic. The notification procedure for blood donors found anti-HIV positive is described, with the importance of confirmation of such results before approach to the donor emphasised. Counselling issues arising from indeterminate and false positive lest results are explored and those arising from enquiries generated by cases of possible post-transfusion HIV infection are examined.     

Reflex responses of human lip muscles to mechanical stimulation during speech

The role played by reflex pathways in the production of movement has been a significant issue for motor control theorists interested in a wide variety of motor behaviors. From studies of locomotion and chewing, it appears that gains in reflex pathways can be altered so that activity in these pathways does not produce destabilizing responses during movement. In speech production, recent experimental evidence has been interpreted to suggest that autogenetic lip reflexes (perioral reflexes) are suppressed during sustained phonation or speech production. The present study was conducted to assess the effects of phonation, direction of movement, and ongoing speech production on reflex responses of lip muscles. The present results suggest, in contrast to earlier work, that this reflex pathway is not suppressed or absent because the amplitude of the observed response depends upon the activation levels of the various muscles of the lower lip and, therefore, indirectly on the nature of the gesture the subject is instructed to produce.