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.     

AQUINAS'S ARGUMENT AGAINST SELF-HATRED

Aquinas's argument against the possibility of genuine self‐hatred runs counter to modern intuitions about self‐hatred as an explanatorily central notion in psychology, and as an effect of alienation. Aquinas's argument does not deny that persons experience hatred for themselves. It can be read either as the claim that the self‐hater mistakes what she feels toward herself as hatred, or that, though she hates what she believes is her “self,” she actually hates only traits of herself. I argue that the argument fails on both readings. The first reading entails that all passions are really self‐love, and so is incompatible with Aquinas's own “cognitivist” view of what it is that distinguishes specific passions in experience. The second reading entails that persons have no phenomenal access to “self,” rendering self‐reference—how it is that the self can be an intentional object of conscious mental states—a mystery. Augustine's claim, which Aquinas accepts on authority, that all sin originates in inordinate self‐love seems to entail the impossibility of genuine self‐hatred because both thinkers fail to distinguish between two distinct forms of self‐love: amor concupiscentiae and amor benevolentiae.     

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.     

Comparison of response formats for Multidimensional Health Locus of Control Scales: six levels versus two levels

Two formats of the Multidimensional Health Locus of Control (MHLC) Scales were administered to 54 college students. Each subject completed the MHLC Scales in the standard 6-level response format (ranging from strongly disagree to strongly agree) and in a revised 2-level format (ranging from disagree to agree). Comparisons of internal consistency measures, principal components, and classification of subjects into groups indicate that the 2-level response format yields comparable data to those obtained with the 6-level format, particularly when classification of subjects is the goal.     

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.     

Heat and Violence: New Findings from Dallas Field Data, 1980–19811

Research in both laboratory and field settings has suggested a link between thermal stress and violent behavior, and both linear and curvilinear models have been investigated. A dearth of field studies prompted the analysis reported here, which is based on data for some 10,000 aggravated assaults occurring the City of Dallas in 1980 (a summer of severe heat stress) and 1981. This analysis replicates and extends certain aspects of recent work by Anderson and Anderson (1984) relating to the so-called linear and curvilinear hypotheses. Thermal stress is measured in two ways: a Discomfort Index (DI), which takes into account the influence of humidity acting in concert with temperature, and ambient temperature. Regression analyses were performed in two stages. In the first, data for all neighborhoods and all days of the study period were combined into ambient temperature and DI models. At the second stage, models differentiated between the three levels of neighborhood socioeconomic status. With weekend controlled, DI and ambient temperature were significant independent variables in the ‘overall’ model and in medium and low status neighborhoods. However, when linear effects were controlled, the curvilinear measures were never significant. The analysis generally tended to confirm Anderson and Anderson's suggestion that a reduction of aggression with increasing temperature does not appear to occur within the normal range of temperatures. This analysis further suggested that the hypothesized curvilinear effect is weak, if not entirely absent, even during conditions of extreme heat.