Sequencing strategies in children 18–24 months: Limitations imposed by task complexity

Researchers have generally reported that very young children lack the orderly, sequential approach to tasks that characterizes skilled action. This study questions that assumption by investigating to what extent deficits in sequencing are a function of task complexity (type and number of elements), and to what extent sequencing ability is tied to competent task performance. Three tasks—the Lock Box, Pegboards, and Object Grouping—were each presented in two forms, varying only in number of elements. Participants were 38 children between 18 and 24 months of age. The Denver Developmental Screening Test was also administered to all children. When number of task elements increased, there was a dramatic decrease in orderliness of approach. Type of task served to exaggerate or minimize these effects. However, irrespective of task complexity, children used a consistent pattern of organization, generally two or three sequential movements. This strategy, though serving well for tasks of limited dimensions, was inadequate for tasks with more than four or five elements. Sequencing skills, as well as other aspects of performance, were significantly correlated with Denver scores. Results suggest that exceeding the limits of young children's organizing abilities may obscure actual capacities. The role of task complexity in the performance of young children is discussed as it relates to developmental processes, clinical assessment, and teaching.     

Stimulus intrusion on fixed-interval responding in the rat: The effects of electric shock intensity,temporal location,and response contingency

After a scalloped lever-press response pattern had developed under a fixed-interval food reinforcement schedule, a 15-sec electric shock was intruded for different groups of rats in the first, second, third, or fourth quarter of each inter-reinforcement interval. Shock intensity was systematically increased for individual rats over 70 sessions, from 0.05 to 1.6 mA. Additional between-groups comparisons involved response-dependent versus clock-dependent fixed-interval schedules, and response-dependent versus response-independent electric shock intrusion. Response rates within each fixed interval prior to, during, and following electric shock intrusion showed regular and reproducible increases and decreases under systematic application of the experimental variables. These results provide further evidence that the functions of a stimulus are determined in part by the parameters of intensity, response contingency, and temporal location with respect to reinforcement.     

Token test performance by dyslexic adolescents

An abbreviated form of the Token Test was administered to 42 normal readers and 42 dyslexic adolescent males. The greatest divergence between the two groups was seen on Part V where syntactic complexity varies. An error analysis also supported the hypothesis that some, but not all, dyslexics have an impaired ability to process syntactic information. The Token Test, particularly Part V, would be a useful aid in the evaluation of dyslexic individuals.     

Comparing natural and abstract categories: A case study from computer science

In order to address the issue of whether abstract and concrete objects are categorized similarly, this paper looks at how computer scientists categorize the common concepts of their field. Using the methodology of Rosch, Mervis, Gray, Johnson, and Boyes-Braem (1976) and of Rosch and Mervis (1975) to identify the categorizations used by computer scientists, this study found that the categorization phenomena reported for concrete objects are quite general, operating over a wider range than was previously thought.