Of beasties and butterflies: Evidence for the stability and domain-specificity of individual differences in categorization

Previous research has failed to demonstrate unambiguously the relative stability across time and consistency across tasks of individual differences in categorization, or categorization breadth The present study of categorizing behavior in college students assesses breadth at each of four points in time over a six-week period Results are consistent with an interpretation of breadth as a highly stable individual difference variable, but one that is constrained by the nature of the stimulus sets employed High stability coefficients were observed for each of two redundant tasks In contrast, cross-task consistency indices were generally low Personality correlates of breadth were similarly weak and inconsistent Several variables are suggested that may attenuate the generality of categorization breadth The existence of multiple styles of categorization is discussed     

Sex typing and division of labor as determinants of marital change across the transition to parenthood

This investigation examines the proposition that wives who describe their personality in ways that deviate from sex stereotypes will become less positive and more negative about their marriage from before to after they become mothers, particularly when the transition to parenthood is accompanied by an increase in the traditionalism of marital roles. Sixty-one couples were studied longitudinally from the last trimester of pregnancy through the third postpartum month. The wives completed the Personal Attributes Questionnaire (Spence & Helmreich, 1978), which measures the extent to which they ascribe personality attributes stereotyped as "masculine" (i.e., instrumental, agentic) and "feminine" (expressive, affectional) to themselves, and several questionnaires assessing the marital relationship at both times of measurement. Results revealed that the more division of labor changed toward traditionalism, the greater the decline in wives' evaluations of the positive aspects of marriage and that changes in wives' evaluations of both positive and negative aspects of marriage can be significantly predicted by the interaction of the wives' expressivity and changes toward increased traditionalism in division of labor. Additional analyses showed that wives who do not ascribe female sex-typed attributes to themselves (relative to those who see themselves in sex-stereotyped ways) are more apt to evaluate their marriage less favorably from before to after parenthood when roles shift toward greater traditionalism.     

Determinants of sexual and dating behaviors among adolescents

The study of adolescent sexual development has typically focused on the incidence and age of onset of particular behaviors. Recent developments in the analysis of covariance structures permit more powerful simultaneous tests of the determinants of adolescent sexual behavior. These new methods allow the assessment and evaluation of the interrelatedness between unobserved, latent constructs. Data were obtained from 183 males and 193 females ranging in age from 12 to 18 years old, selected from three birth cohorts using a stratified random sample. Eight latent constructs--Sexual and Dating Involvement, Self-Acceptance, Feminist Sex Role Attitudes, Deviant Social Network, Importance of Dating, Lack of Heterosexual Competence, Sexually Active Social Network, and Stressful Change Events--were hypothesized to explain the variance in 26 observed variables. Several causal models were tested that specified structural relationships among the latent constructs. A theoretically meaningful model was arrived at that linked the eight, error-free factors.     

Auditory word discriminations in the pigeon.

Four pigeons were trained on a multiple variable-interval 30-s extinction schedule with various pairs of spoken English words presented as the discriminative stimuli. The birds typically produced discrimination indices of 70% to 90% accuracy. Discrimination accuracy was improved by shortening the interval between auditory stimulus presentations, and by increasing the number of syllables in the words.     

More on concurrent interval-ratio schedules: a replication and review.

It has been suggested that the failure to maximize reinforcement on concurrent variable-interval, variable-ratio schedules may be misleading. Inasmuch as response costs are not directly measured, it is possible that subjects are optimally balancing the benefits of reinforcement against the costs of responding. To evaluate this hypothesis, pigeons were tested in a procedure in which interval and ratio schedules had equal response costs. On a concurrent variable time (VT), variable ratio-time (VRT) schedule, the VT schedule runs throughout the session and the VRT schedule is controlled by responses to a changeover key that switches from one schedule to the other. Reinforcement is presented independent of response. This schedule retains the essential features of concurrent VI VR, but eliminates differential response costs for the two alternatives. It therefore also eliminates at least one significant ambiguity about the reinforcement maximizing performance. Pigeons did not maximize rate of reinforcement on this procedure. Instead, their times spent on the alternative schedules matched the relative rates of reinforcement, even when schedule parameters were such that matching earned the lowest possible overall rate of reinforcement. It was further shown that the observed matching was not a procedural artifact arising from the constraints built into the schedule.     

Once more on the equilibrium-point hypothesis (lambda model) for motor control

The equilibrium control hypothesis (lambda model) is considered with special reference to the following concepts: (a) the length-force invariant characteristic (IC) of the muscle together with central and reflex systems subserving its activity; (b) the tonic stretch reflex threshold (lambda) as an independent measure of central commands descending to alpha and gamma motoneurons; (c) the equilibrium point, defined in terms of lambda, IC and static load characteristics, which is associated with the notion that posture and movement are controlled by a single mechanism; and (d) the muscle activation area (a reformulation of the "size principle")--the area of kinematic and command variables in which a rank-ordered recruitment of motor units takes place. The model is used for the interpretation of various motor phenomena, particularly electromyographic patterns. The stretch reflex in the lambda model has no mechanism to follow-up a certain muscle length prescribed by central commands. Rather, its task is to bring the system to an equilibrium, load-dependent position. Another currently popular version defines the equilibrium point concept in terms of alpha motoneuron activity alone (the alpha model). Although the model imitates (as does the lambda model) spring-like properties of motor performance, it nevertheless is inconsistent with a substantial data base on intact motor control. An analysis of alpha models, including their treatment of motor performance in deafferented animals, reveals that they suffer from grave shortcomings. It is concluded that parameterization of the stretch reflex is a basis for intact motor control. Muscle deafferentation impairs this graceful mechanism though it does not remove the possibility of movement.     

Daily versus major life events as predictors of symptom frequency: a replication study

Predictions of physical symptomatology by daily life events and by major life events were compared, replicating and expanding work reported by DeLongis, Coyne, Dakof, Folkman, & Lazarus (1982). Analyses of daily, prospective data collected on 79 married men for 90 days demonstrated that daily, undesirable events were better predictors of symptom frequencies than either past, major life events or daily, desirable events. These results, similar to those found by DeLongis et al. (1982), were further explored by examining "healthy" subjects versus subjects with prior medical conditions. Undesirable daily events were a much stronger predictor of physical symptoms in the healthy group than in the prior medical conditions group.     

Facilitation in letter detection with sequentially presented homophonic strings

A consistent phonology between sequentially presented pseudoword quadrigrams was found to improve performance in a letter-detection task. Each of 8 subjects was required to judge whether an M appeared in either the initial or terminal position of letter strings. The letter N was used as a foil. For each presentation, two quadrigrams appeared sequentially, the first for 20 ms and the second for a duration that allowed approximately 75% overall accuracy. The strings differed only by the letter next to the one on the opposite end of the string from the M or N. Subjects were not told that two strings were exposed on each presentation, and when asked, none reported having been aware of this. Nevertheless, detection was significantly better when the two strings were homophones (e.g., SERM, SIRM) than when they were not (e.g., SARM, SORM). Results are discussed in terms of phonological access to the mental lexicon.     

Do semantic memory deficiencies underlie learning disabled readers' encoding processes?

This study investigates the extent to which learning disabled readers' atypical encoding relates to their deficiencies in semantic memory. Inferences related to ability group performance were based on the assumption that encoding involves the matching of incoming information against a featural representation of that information in semantic memory. To this end, learning disabled and nondisabled readers in two age groups were compared on dichotic listening recall tasks that included orienting and nonorienting instructions. Orienting instructions directed children's attention toward semantic, phonemic, or structural word features. Dependent measures were lateralization, free recall, retrieval organization, and selective attention. The efficiency of allocating attentional resources was inferred from correlations between central and incidental recall. Primary results included the following: Disabled and nondisabled readers' ear asymmetry differences were dependent upon age, orienting instructions, and type of word list; disabled readers' recall and organization scores were lower than skilled readers'; however, both ability groups benefitted from orienting instructions compared to nonorienting instructions; during orienting instructions, disabled readers were less able than skilled readers to divide their attention between target and nontarget word features, especially during interhemispheric processing conditions; and the relative efficiency of allocating attentional resources differed qualitatively between the two ability groups. The results suggest that ability group variations reflect the structure of the memory trace in interaction with ear presentation and encoding processes. It is inferred that disabled readers' inferior memory traces reflect the quantity and internal coherence of information stored in semantic memory as well as the means by which such information is accessed.