Sensitivity to reinforcement in concurrent arithmetic and exponential schedules

The generalized matching law states that the logarithm of the ratio of responses emitted or time spent responding in concurrent variable-interval schedules is a linear function of the logarithm of the ratio of reinforcements obtained. The slope of this relation, sensitivity to reinforcement, varies about 1.0 but has been shown to be different when obtained in different laboratories. The present paper analyzed the results from 18 experiments on concurrent variable-interval schedule performance and showed that response-allocation sensitivity to reinforcement was significantly smaller when arithmetic, rather than exponential, progressions were used to produce variable-interval schedules. There were no differences in time-allocation sensitivity between the two methods of constructing variable-interval schedules. Since the two laboratories have consistently used different methods for constructing variable-interval schedules, the differences in obtained sensitivities to reinforcement are explained. The reanalysis suggests that animals may be sensitive to differences in the distribution of reinforcements in time.     

Occupational perceptions of academic disciplines

This study investigated the way in which various academic disciplines are viewed by students with respect to their “specificity,” i.e., the degree to which each is related to all occupations after graduation, and their “utility,” i.e., the extent to which each facilitates obtaining employment after graduation. A consensus concerning the specificity and utility of 17 academic disciplines was found for a sample of 485 sixteen- to eighteen-year-olds. This consensus was reliably demonstrated on other independent samples; nevertheless, some differences between individual disciplines were found as a function of sex and type of school attended.     

Memory in educable mentally retarded adults: Deficit in subject or experimenter?

Educable mentally retarded (EMR) and nonretarded adults free recalled lists of (a) words, (b) minitasks performed by the subjects (SPTs), (c) minitasks performed by the experimenter (EPTs), or (d) task instructions. The EMR subjects were significantly inferior to the nonretarded subjects in the immediate recall of words, EPTs and instructions, but not in the immediate recall of SPTs. This proficiency of the EMR subjects in SPT recall was attributed to the nonstrategic nature of this test. The EMR subjects were, however, inferior to the nonretarded subjects in a final free recall (recall of all lists) of all four types of item.     

The relationship of personality to antisocial and neurotic behaviours as observed by teachers

Eight hundred and eight children in normal schools between the ages of 7 and 16 yr were rated on Rutter's Teachers' Rating Scale, and completed the EPQ giving Psychoticism (P), Extraversion (E), Neuroticism (N) and Lie (L). The children also reported on their own misbehaviour and social attitudes. Children exhibiting Antisocial behaviours were markedly high on P; also scoring low on L, and reporting non-conforming behaviour and attitudes. Children showing Neurotic behaviours did not have particularly distinctive personality scores, but were rather extraverted and conforming (high L). There was no relationship between Neuroticism as a disorder and Neuroticism as a personality trait. It is suggested that the P scale might usefully assist in the detection of antisocially disturbed children or in the selection of ‘high risk’ groups.     

Sex differences in spatial ability and spatial activities

Explanations of sex-related differences in spatial ability emphasizing the role of sex-differentiated experience have not been supported by direct measurement of spatial activities during adolescence, the period when these differences seem to increase. The present research involved development of a scale to measure the spatial experience of adolescents and adults. In Study 1, a list, as complete as possible of adolescent activities was compiled and given to undergraduate judges for ratings of involvement of spatial skills and sex-typing. Judges also indicated whether they had participated in each activity. Activities considered spatial by 75% or more of the judges were used to develop a spatial experience questionnaire. Judgments of the spatial nature of tasks were positively correlated with judged masculinity and with greater male than female participation. In Study 2, participation in spatial activities by undergraduates was correlated with spatial ability as measured by the Differential Aptitude Test. The activity questionnaire should prove useful in studying the development of spatial ability in adolescents and adults.     

Tarski on “essentially richer” metalanguages

It is well known that Tarski proved a result which can be stated roughly as: no sufficiently rich, consistent, classical language can contain its own truth definition. Tarski's way around this problem is to deal with two languages at a time, an object language for which we are defining truth and a metalanguage in which the definition occurs. An obvious question then is: under what conditions can we construct a definition of truth for a given object language. Tarski claims that it is necessary and sufficient that the metalanguage be essentially richer. Our contention, put bluntly, is that this claim deserves more scrutiny from philosophers than it usually gets and in fact is false unless essentially richer means nothing else than sufficient to contain a truth definition for the object language.     

Availability of family support as a moderator of exposure to community violence.

Examined the role of availability of family support in moderating the negative effects of exposure to community violence on internalizing symptoms. Participants were 75 low-income African American children between the ages of 10 and 15. Two measures of availability of family support (mother's presence in the home and family size) were evaluated as moderators of the relations between exposure to community violence and depression and posttraumatic stress disorder (PTSD) symptoms. After controlling for age, sex, and concurrent life stress, mother's presence in the home moderated the relation between exposure to community violence and depressive symptoms but not the relation between exposure to community violence and PTSD symptoms. Children living in mother-absent families were at increased risk of depressive symptoms as exposure to community violence increased. In addition, family size approached significance as a moderator of depressive symptoms but not PTSD symptoms, revealing a trend toward children from smaller families being at increased risk of depressive symptoms as exposure to community violence increased. These findings suggest that although availability of family support is an important moderator for depressive symptoms, this is not the case for PTSD symptoms.