Categorization and representation of physics problems by experts and novices

The representation of physics problems in relation to the organization of physics knowledge is investigated in experts and novices. Four experiments examine (a) the existence of problem categories as a basis for representation; (b) differences in the categories used by experts and novices; (c) differences in the knowledge associated with the categories; and (d) features in the problems that contribute to problem categorization and representation. Results from sorting tasks and protocols reveal that experts and novices begin their problem representations with specifiably different problem categories, and completion of the representations depends on the knowledge associated with the categories. For, the experts initially abstract physics principles to approach and solve a problem representation, whereas novices base their representation and approaches on the problem's literal features.     

Developmental changes in free recall: The interaction of task structure and age

Free-recall learning and organization were measured for 3rd, 7th, and 11th graders under conditions which varied the type and amount of task structure. Task structure for the input or list-presentation phase was manipulated by using a random, constant, or alphabetic item sequence across trials. Task structure for the output or recall phase was manipulated by providing standard instructions or instructions which suggested the possible use of an alphabetic ordering scheme. Recall performance and organization showed an interaction between age and both manipulations of task structure. The 3rd graders required the maximal amount of task structure (alphabetic order with alphabetic instructions) to demonstrate recall facilitation relative to the completely unstructured control condition. The 7th graders showed recall facilitation for intermediate and high levels of task structure, and the 11th graders showed recall facilitation for low, intermediate, and high levels of task structure. The results are related to current hypotheses about developmental changes in recall performance and their relationship to changes in the systematic use of organizational strategies.     

Age differences in memory span

Five-year-olds recalled fewer items than adults in memory-span tasks involving both familiar and unfamiliar faces. This occurred even though the use of rehearsal and recoding strategies was minimized for adults. This residual age difference may be partially accounted for by two further processing limitations in children. The five-year-olds needed more time than adults to name a face (Experiment 1) and to encode a face (Experiment 2). In order to test whether limitations in children's initial recognition and stimulus-identification processes could account for recall performance, Experiment 3 reduced adults' exposure duration in the memory-span task. This led to a drastic reduction in the age difference. Other factors contributing to remaining age differences included adults' adaptability in using various alternative encoding and retrieval strategies which elevated their recall performance.     

Barrier effects in the cognitive maps of children and adults

To study spatial representation, Kosslyn, Pick, and Fariello (Child Development, 1974, 45, 707–716) asked preschoolers and adults to learn toy locations in a room divided into quadrants. When asked to rank order the closeness of toys, preschoolers exaggerated distances between objects separated by opaque or transparent barriers; adults distorted across opaque barriers only. The findings were interpreted as showing that children's spatial representations may rely more than adults' on functional distance and/or that children may have more difficulty than adults keeping many objects in mind simultaneously (integrative processing capacity). The Kosslyn et al. procedure was repeated here with first graders and adults, using either rank ordering techniques or direct distance estimations. Interactions of age and barrier appeared for the rank ordering measure only. Children showed a greater tendency than adults to group their rankings by quadrant. With the distance estimation measure, adults were quantitatively more accurate than children, at least among males; barrier effects interacted with sex and distance, but not age. These findings suggest the importance of integrative processing capacity, and that different dependent measures may tap different processes.