Regional brain activity in dyslexic and control children during reading tasks: Visual probe event-related potentials

Event-related potentials (ERPs) elicited by task-irrelevant visual stimuli were recorded from 34 control and 32 dyslexic 10- to 12-year-old boys while they performed silent and oral reading at two levels of difficulty. All subjects were extensively screened for neurological problems, IQ, and sensory acuity. Specific features of the ERPs were affected in amplitude and latency by the experimental variables: group membership, oral vs. silent reading, difficulty level, and recording site (within and between hemispheres). A specific effect of difficulty on the central and parietal ERP was seen in the dyslexics but not the controls. Different patterns of asymmetry were found for the two groups in silent vs. oral reading at midtemporal placements. A marked asymmetry (R > L) was found at the midtemporal region for both groups.     

Cognitive differentiation as a function of information type and its relation to career choice

Although providing occupational information is a common vocational counseling practice, recent research has raised questions about the utility of such information. Cognitive differentiation (the ability to differentiate among job titles on 12 constructs) has been shown to be positively related to an “appropriate” career choice. Differentiation, however, appears to decrease as a function of traditional types of occupational information (e.g., Occupational Outlook Handbook, U.S. Department of Labor, Washington, D.C., 1980). The present study investigated the hypothesis that information related to Holland personality characteristics of persons in various occupations would increase subjects' ability to differentiate among those job titles. One hundred fifty undeclared-major freshman undergraduate students were randomly assigned to one of three condition groups: objective information, personality information, no information. All subjects were administered the Career Decision Scale and Cognitive Differentiation Grid. Results indicated that subjects receiving personality information exhibited a significantly greater degree of differentiation among careers than subjects receiving objective information. These results confirm the major hypothesis of the study and suggest that the provision of personality information may be more useful in promoting career choice than the types of information traditionally provided.     

Dissociation between conditioned emotional response and extended avoidance performance

The present experiments examined the dissociation between the strength of a shuttlebox avoidance response (AR) and one index of fear of the avoidance CS. Avoidance response strength was indexed by resistance to extinction of the AR and by changes in response latency, and fear of the CS was indexed by the conditioned emotional response (CER) technique. Experiments 1, 2A, and 3A all found that rats trained to a criterion of 27 consecutive avoidance responses (CARs) showed response strength comparable or superior to rats trained to a criterion of 9 CARs. Experiments 2B and 3A demonstrated that rats trained to 27 CARs showed less suppression of bar pressing during the avoidance CS (less CER) than rats trained to 9 CARs. Experiment 3A also found that, when extinguished in the shuttlebox to a moderate criterion (5 consecutive trials without a response) before CER testing, rats trained to 9 CARs showed some, although not complete, loss of CER, whereas rats trained to 27 CARs showed no loss of CER. In Experiment 3B rats that took 1 vs 2 days to reach a criterion of 27 CARs were compared for their AR strength and for their CER. Although rats taking 2 days to reach criterion showed somewhat greater resistance to extinction of the AR than rats reaching criterion in 1 day, this variable had no apparent effect on the CER. Implications of the present results for current theories of avoidance learning are discussed.     

Preference as a function of the correlation between stimuli and reinforcement outcomes

Pigeons' preferences for stimuli that were to varying degrees correlated with outcomes were studied in two experiments using a concurrent-chain procedure. The pigeons chose between two terminal links, each ending with food reinforcement and with blackout on half of the trials. In the first experiment, one terminal link (nonpredictive or unreliable link) provided stimuli completely uncorrelated with the outcomes while the other terminal link (predictive or reliable link) provided stimuli that were, to varying degrees, correlated with these outcomes. All pigeons showed increasing preferences for the predictive link as the reliability of the stimuli in that link increased. In the second experiment, stimuli in both terminal links were differentially correlated with the outcomes. The pigeons again preferred the more reliably correlated terminal link. The relation between these results and the delay-reduction hypothesis and conditioned reinforcement account is noted. The behavioral value of predictive stimuli may lie in their permitting the organism to more effectively apportion its time between interim activities and terminal responses.     

A reinforcement plus interruption method of eliminating behavioral stereotypy of profoundly retarded persons

Stereotyped responses have been shown to be eliminated by an overcorrection-reinforcement program. The present study evaluated response-interruption as an alternative to the overcorrection component with seven profoundly retarded adults. During the baseline praise condition, stereotypy occurred during 66% of the observations for the seven profoundly retarded adults but decreased to less than one response per half hour in a mean of two sessions of individual training. In the subsequent class situation, stereotypy was reduced to less than 5% on the first day of class, to less than 1% by the fourth day and less than one stereotypy per hour after the third day. The interruption method seems preferable to postural overcorrection because of its apparent and relative nonaversiveness.     

Children's cognitive maps of large-scale spaces: Effects of exploration,direction, and repeated experience

Kindergarteners and third graders (mean ages 5–10 and 8–9 years) repeatedly encountered a model town and then constructed the town from memory. In Experiment 1, the effect of different types of exploration on the development of a cognitive map was assessed. Children who were directed to walk within the town placed buildings more accurately than children who had walked along the town's perimeter. Children who walked within the town and were directed to the spatial relationships among buildings had the highest placement accuracy. Third graders were more accurate than kindergarteners across the three types of exploration. In Experiment 2, children were permitted to explore the town alone for an unlimited amount of time. Under these conditions, third graders still placed buildings more accurately than kindergarteners. A comparison of Experiments 1 and 2 indicated that children developed more accurate cognitive maps when motor activity and attention were directed by the experimenter as opposed to being directed by the child. Accuracy improved with repeated walks and constructions in both experiments, and the results of Experiment 3 suggested that constructing facilitated the development of the cognitive map as much as walking. It was concluded that third graders' cognitive maps were more accurate than kindergarteners' maps due to differences in the speed of acquisition and storage of spatial information.     

Children and adults' distance estimations in a large-scale environment: effects of time and clutter

In two experiments adults (mean age = 19-5), sixth graders (mean age = 11-8), fourth graders (mean age = 9-8), and second graders (mean age = 7-8) walked a straight line distance through a large-scale environment. Subjects were then asked to estimate the time taken to traverse each half of the walk and to estimate the distance between objects seen along the walk. In Experiment 1 each half of the walk was traversed in the same amount of time but contained a different number of objects (clutter). Time and distance estimates were related, but were not affected by the number of intervening objects encountered between locations. In Experiment 2 subjects again encountered a different number of objects along each half of the walk but each half was traversed in varying amounts of time. Again, time and distance estimates were related, and there was no clutter effect. There were no consistent developmental differences across the two experiments. It was concluded that (1) Thorndyke's clutter effect does not occur across all types of spatial cognition tasks, and (2) children and adults tend to relate time and distance across a variety of distance estimation tasks.     

Behavioral performances in participants with phonological dyslexia and different patterns on the N170 component

Adults with phonological dyslexia and controls performed a lexical decision task while ERPs were recorded in the occipitotemporal pathway. Based on N170 durations, two subgroups were formed: dysl1 showing longer N170 durations and dysl2 showing normal N170 durations. While the dysl1 subgroup had poorer accuracy for infrequent words and pseudo-words, the dysl2 group responded more slowly than controls to pseudo-words. N170 amplitudes were larger in the left hemisphere for controls irrespective of items. In the dysl1 subgroup, N170 amplitudes were larger in the left hemisphere than the right for words but not for pseudo-words, a sign of hemispheric compensation, while in the dysl2 subgroup signs of bilateralization were observed. Moreover, in the dysl1 subgroup, P100 amplitudes were smaller than controls. These results indicate different behavioral profiles of dyslexics with different patterns of P100 and N170 components. The ERP changes may be due to different behavioral strategies employed by each subgroup, logographic in dysl2 and phonological in dysl1.