Writing induces a right hemisphere linguistic advantage in dysphonetic dyslexic children: implications for attention and capacity models of laterality

An experiment demonstrated a complete hemispheric processing reversal in 10 male, dysphonetic dyslexic children that occurred during a dichotic listening test of their verbal working memory. Requiring a written response to dichotic digits produced a right hemisphere/left ear superiority in the dysphonetic dyslexics whereas normal subjects and other dyslexics maintained a left hemisphere/right ear advantage. This reversal was unaffected by changes in task difficulty. A second experiment assessed the influence on producing the reversal of concurrent manual interference with left hemisphere verbal processing (responding orally vs. manually) and selective right hemisphere priming (Forward Writing vs. Backward Writing). The dysphonetic children reverted to a strong left hemisphere superiority when recalling the dichotic digits orally. Backward writing produced no ear advantage in either direction. The findings suggest that dysphonetic dyslexia may be related to (1) left hemisphere processing demands that exceed capacity, (2) easily activated right hemisphere processing strategies and (3) failure to coordinate linguistic processing interhemispherically. The results supported a novel hybrid conceptualization of dyslexia consisting of a synthesis of selective activation, and dual processor-limited capacity, theories.     

Hemispheric lateralization in 47,XXY Klinefelter's syndrome boys

Thirty-two boys with a 47,XXY karyotype were compared with chromosomally normal male controls in their performance on six tasks of hemispheric specialization. The results revealed that the 47,XXY subjects had smaller asymmetries on left hemisphere tasks and larger asymmetries on right hemisphere tasks than controls. Analyses of individual right and left side scores revealed that the atypical lateral asymmetries of the 47,XXYs were due to a shift toward greater right hemisphere involvement on four of the six measures. It was postulated that the slower fetal growth rates of the extra X chromosome group might contribute to their atypical hemispheric specialization and the failure of their left hemisphere to gain dominance over their right in language processing.     

Motivation and learning: Neurophysiological mechanisms in a “model” system

The neurophysiological mechanisms underlying behavioral motivation and associative learning are described in an invertebrate “model” system, the carnivorous marine mollusc Pleurobranchaea. Feeding motivation can be controlled via nutritional history and is represented centrally in the feeding motor network as a change in the balance of synaptic excitation and inhibition at the level of interneurons that initiate feeding behavior, i.e., feeding “command” interneurons. Associative learning, induced by avoidance conditioning of feeding behavior, manifests identically at the level of the command interneurons, but is distinguished from non-associative motivational changes by processes that occur in identified neurons and pathways presynaptic to the command interneurons. Motivation and learning are therefore linked mechanistically by convergent neurophysiological mechanisms at the level of central neurons that initiate behavior.     

The genetic context of perceptual imprinting: Canalization by stimulus preference

Recent data from various sources converge in pointing to constitutional constraints and genetic influences in behavioral development. What are the mechanisms that mediate such constraints and influences? Are they expressed through mechanisms of behavior acquisition and learning? Or are they expressed through genetically determined perceptual capacities and response propensities that guide behavior along species-typical and ontogenetically adaptive developmental trajectories? These alternatives are examined in the context of genetically and environmentally manipulated stimulus preferences and perceptual imprinting in Japanese quail chicks (Coturnix coturnix japonica). Data indicate that the genotype is a source of variation in unconditional stimulus preferences and that there are inhibitory and facilitative interactions between different unconditional preferences and also between unconditional and acquired preferences. Variations in stimulus-specific and stimulus-general learning may guide behavioral development in ways that are genetically preadapted, yet individually variable, and ontogenetically adaptive. Interpretation of data favors a synthesis of earlier psychological and biological concepts of canalization.     

Uncovering mental processes with factorial experiments

The analysis of reaction time (RT) additivity and interactions via factorial manipulation is a widely used and potentially powerful tool for elucidating mental processing; however, current implementation is limited by the scope of systems for which predictions are available, as well as statistical weakness. Predictions for an expanded set of system dimensions (serial/parallel, independent/dependent, and selective/nonselective influence) are given. The theorems are not limited to particular families of distributions. Statistical considerations are examined in the context of an exemplary nonadditive parallel system which adequately fits “additive” data but will only be rejected as additive when power is increased beyond the traditional criteria.     

The influence of mood on perceptions of social interactions

Interpreting our own and others' social behaviors is an important cognitive task in everyday life. Recent work in cognitive psychology suggests that temporary mood states may have a significant effect on the way information about common social events is processed. This study investigated how (a) a person's current mood, (b) the target of the judgments (self vs other), and (c) the characteristics of the social episode (formal-informal; intimate-nonintimate) influenced people's assessment of, and memory for, social behaviors. Subjects were videotaped while engaging in four different kinds of interactions with trained confederates. One day later subjects were hypnotized, and a happy, positive, or depressed, negative mood was induced. They then watched and rated their own and their partner's interactions on the videotape. Results showed strong mood influence on behavior assessments and recall memory, and significant effects due to target (self vs other) and the type of interaction episode. These results are discussed in terms of their implications for contemporary research on social cognition, and their relevance to cognitively based theories of social maladjustment and depression are considered.     

Improving visual acuity in a myopic child: Assessing compliance and effectiveness

Improvements in visual acuity following vision training were evaluated for an 11$\text{1}\text{2}$-yr-old myopic male. Initial increases in the distance at which the S could discriminate letters were found. However, performance began to deteriorate as training progressed. A negative-reinforcement procedure was employed in order to rule out motivational factors potentially related to this decreased performance. Using a changing criterion within an ABCBC reversal design, the distance at which the S correctly discriminated letters increased by more than $\text{4}\text{1}\text{2}$ times and was clearly related to the reinforcement procedure.     

A laboratory test of the constant risk hypothesis

It has been repeatedly suggested that subjects aim at maintaining a constant error probability in many variants of self-paced performance and that they adjust their behaviour so as to keep their risks relatively constant. This constant risk hypothesis is investigated in a simple computer-controlled addition task it which subjects manipulated exercise difficulty as a function of their own calculation proficiency and the allotted solution time. Error probability proved to be unrelated to level of skill and to amount of allotted computation time, but to depend onuncertainty with respect to exercise difficulty.     

Response probability and similarity of retrieved response tendencies as determinants of response suppression difficulty

The primary objective of this study was to test the validity of the here labelled ‘suppression-time’ assumption which contends that the more difficult the response suppression operation, the longer the time required for its successful implementation. A secondary interest addressed the possibility that output suppression difficulty would be influenced by the level of response-response (R-R) compatibility existing between retrieved response tendencies. Two basic requirements confronted subjects within an experimental session: (a) dual-initiation (Dual-I) of paired arm movements, (b) initiation/suppression (I/S) of retrieved outputs, the irrelevant response being suppressed, the relevant output initiated. RT(I/S) magnitude and failure-to-inhibit error frequency increased as response probability increased, thereby providing support for the ‘suppression-time’ assumption. But R-R compatibility degree variations, when realized, did not consistently affect response suppression difficulty.