Acknowledgement

Four experiments examined the effects of noise on semantic memory. The first was a replication of a study by Eysenck, in which subjects had to retrieve words beginning with particular letters which were also instances of specified categories (e.g. Fruit-A). Whereas Eysenck had found that both noise and activation level of the individual interacted with the dominance of the category instance possible, the present study failed to repeat the findings.The remaining experiments used a paper-and-pencil modification of Eysenck's technique; the second and third were successful in showing interactions of dominance and noise, but in opposite directions. The two experiments differed only in the previous experience of the subjects. In a fourth experiment, the same materials were presented in a different sequence, mixing dominant and non-dominant instances. The interaction then disappeared again.These experiments therefore suggest that the effect of noise on memory is not a uniform and mechanical exaggeration of dominance, but depends on the retrieval strategies being employed by the particular subject.     

MENTAL ARITHMETIC IN AFRICA AND AMERICA: STRATEGIES,PRINCIPLES, AND EXPLANATIONS*

Mental arithmetic abilities were studied among unschooled African adults and American college students. A set of problems tested the use of the four basic arithmetic operations. Performance was analyzed for: strategies, implicit arithmetic principles, and explicit explanations of the principles. Both groups showed accurate mental arithmetic strategies related to the base ten structure of their native counting systems. The American students' mental strategies additionally made use of algorithms based on written place values. Several principles were implicit in the calculation strategies of both groups, and both used these principles to short-cut calculations. Though the African subjects did not, the American subjects did describe these abstract principles in explicit common language or algebraic expressions. Relationships between schooling and cognition are discussed.     

Cortical substrates of taste aversion learning: dorsal prepiriform (insular) lesions disrupt taste aversion learning

The functional relation between restricted damage to ventral primary somatosensory neocortex and the ability of rats to acquire conditioned taste aversion (CTA( was examined by a combination of behavioral and neurohistological techniques. Lesions confined exclusively to the established gustatory neocortex (GN) did not disrupt CTA acquisition, nor did lesions confined to suprarhinal cortical areas ventral to the GN. Lesions that encroached on dorsal prepiriform and insular cortices produced CTA acquisition deficits and damaged a large proportion of efferent projections to the prefrontal and precentral neocortex. In a second experiment, lesions of dorsal prepiriform and insular cortices did not modify taste preference-aversion threshold to any of the four taste modalities. It is concluded tha ventral somatosensory neocortical fields, including the established GN, do not mediate CTA acquisition and that rhinal cortices ventral and posterior to the GN are preferentially involved in associative learning for tastes and illness.     

RITALIN VS. RESPONSE COST IN THE CONTROL OF HYPERACTIVE CHILDREN: A WITHIN-SUBJECT COMPARISON

A within-subject comparison was made of the effects of methylphenidate (Ritalin) and response cost in reducing the off-task behavior of two boys, 7 and 8 years of age, who had been diagnosed as having an attentional deficit disorder with hyperactivity. Several dosages of Ritalin (5 to 20 mg/day) were evaluated with the results indicating varying effects of the drug for both children. Response cost (with free-time as the reinforcer) was superior to Ritalin in raising levels of on-task behavior and in improving academic performance.     

TRAINING FAMILY THERAPISTS: AN EXPERIMENTAL ANALYSIS

This study implemented and evaluated a training program (a written manual, videotaped models, rehearsal, role plays, and performance feedback) designed to teach five subjects the skills to become effective family therapists. The study examined the therapists' use of three target behaviors: instructing, informing, and praising. The therapists, each paired with a parent and a preschool-aged child (2 1/2–4 1/2 yr old), were trained in the clinic to use, and to teach to the parents, several behavioral skills (e.g., praising, planned ignoring, and time-out) relevant to teaching children compliance to parental instructions. A multiple-baseline design across triads (therapist/parent/child) demonstrated that after the training program was instituted, the therapists increased their rates of instructing, praising, and informing the parents; all parents increased attention to compliance, decreased attention to noncompliance, and increased rates of praise to their children; and all children increased their compliance and decreased their noncompliance.     

Tower of Hanoi performance of retarded young adults and nonretarded children as a function of solution length and goal state

Three experiments were conducted with the Tower of Hanoi task to assess problem solving ability in 6-, 7-, 8-, and 10-year-old nonretarded children and mentally retarded young adults of varying maturational ages. In Experiment 1 we gradually reduced the number of moves required for solution until subjects could solve the 3-disk tower-ending problem. Although all groups experienced difficulty with the standard 7-move problem, all but the trainable retarded group readily solved the 6-move problem. The trainable group did not reach a comparable level of success until the 4-move problem. On the 7-move problem the retarded groups performed at the level of nonretarded groups that were maturationally $\text{1}\text{1}\text{2}$ to 3 years younger. An analysis of first moves indicated that subject groups differed in the strategies they used to solve the problems. In Experiment 2, practice effects were ruled out as a source of the superior performance on the 6- than on the 7-move problem. In Experiment 3, 7- and 10-year-old nonretarded children and mentally retarded young adults did not differ on 5-move problems in which configuration of the goal states was varied. A comparison of all 5-move problems judged to have the same depth of search requirements indicated that the tower-ending problems were significantly easier to solve than the partial-tower-ending problems, which in turn were easier than the flat-ending problems. A limited depth of search capacity sets boundaries on the use of sophisticated strategies and, to a large extent, accounts for the retarded groups' maturational lag.     

The effect of the temporal locus of the introtact probe on the hypothesis-testing strategies of kindergarten children

The hypothesis-testing behavior of kindergarten children in discrimination learning was studied in a factorial design with two temporal placements of introtact probes (pretrial and posttrial) and two types of pretraining (unidimensional and multidimensional). Pretrial probes consisting of a request for the child's current hypothesis were administered in a conventional manner at the beginning of each trial with the stimuli in view and prior to the choice response. Posttrial probes were administered also with the stimuli in view, but after the choice response had occurred and feedback information had been provided. Learning-to-learn experience in solving three pretraining problems was given either with unidimensional simultaneous problems or with more complex multidimensional problems like the criterion tasks. The results indicated that posttrial probes produced superior local consistency, win-stay, and lose-shift probabilities, relative to pretrial probes, for both types of pretraining. Posttrial probes, however, facilitated learning and the testing of valid hypotheses only for multidimensional pretraining. These results are consistent with the hypothesis that posttrial probes constrain the child to be locally consistent and therefore improve short-term efficiency in hypothesis testing under both pretraining conditions. However, posttrial probes produce an improvement in long-term efficiency, and therefore in learning, only when other components of a successful strategy are acquired as in multidimensional pretraining.     

A negativity bias in interpersonal evaluation

Two studies were conducted to demonstrate a bias toward negativity in evaluations of persons or their work in particular social circumstances. In Study 1, subjects evaluated materials written by peers. Those working under conditions that placed them in low status relative to the audience for their evaluations, or conditions that made their intellectual position within a group insecure, showed a clear bias toward negativity in those evaluations. Only individuals who believed their audience to be of relatively low status and at the same time believed their intellectual position to be secure did not show this bias. In Study 2, subjects viewed a videotape of a stimulus person and rated him on several intellectual and social dimensions. Again, subjects believed their audience to be of either relatively high or relatively low status. As a cross dimension, they were given instructions to focus on either the intellectual or the social abilities of the stimulus person while viewing the videotape. A strong main effect of audience status was demonstrated, but only in ratings of intellectual traits; subjects who believed their audience to be of relatively high status rated the stimulus person's intellectual qualities significantly more negatively. Moreover, this effect was independent of the instructional focus subjects had been given. The negativity bias is discussed in the context of previous demonstrations of biases toward weighting negative information more heavily than positive information, as well as previous demonstrations of seemingly pervasive positivity biases in memory and judgment.     

Age and sex differences on the hand test

Investigated age and sex differences on the Hand Test across the life span, while statistically partialing-out the effects of educational level and verbal ability. Subjects were 150 individuals (75 males, 75 females) ranging in age from 20 to 86 years, assigned to one of three age groups on the basis of their chronological age. Participants were administered the Hand Test and the WAIS vocabulary subtest; in addition, years of formal education completed for each subject was obtained. Results indicated that even after statistically adjusting for the effects of education and verbal ability, a number of significant Age. Sex, Age and Sex, as well as Age x Sex interactions were obtained on the Hand Test. It was suggested that, as previous criticisms of projective research with the aged are met, a residue of important personality trends persists.     

Stimulus discriminability in free-operant and discrete-trial detection procedures.

Six pigeons were trained to discriminate different light intensities in four experimental procedures. Experiment 1 compared stimulus discriminability in a yes-no signal-detection task with discriminability measures obtained from two free-operant procedures. Discriminability estimates were significantly lower in the detection procedure. Experiment 2 showed this lowered discriminability to be a function of the delay between stimulus presentation and the availability of the choice-response keys in the standard detection task. In addition, reinforcement sensitivity was lowest when correct choice responses were intermittently, rather than continuously, reinforced.