Models of central capacity and concurrency

According to single channel theory, the ability of humans to perform concurrent mental operations is limited by the capacity of a central mechanism. The theory was developed by analogy with early computers which had a single central processing unit and required sequential processing. These limitations are not likely to be properties of the mind. But now computers have begun to employ extensive concurrent processing, because of the decreasing cost of the necessary hardware. In this review we will try to bring the computer analogy up to date. Theoretical issues important for concurrent systems may be of interest to psychologists and have applications to such problems as the speed-accuracy trade-off. Several hypotheses about the way signals gain access to the central mechanism are reviewed. Recent variations of the single channel theory are discussed, including the hypotheses that more than one process can use the central mechanism at a time, and that some processes do not use the central mechanism and can be executed concurrently with those that do. In addition, relevant concepts from scheduling theory and operating systems theory are introduced and difficulties encountered by concurrent systems, namely complexity, deadlocks, and thrashing, are discussed.     

Sensitivity in spectral structures

Invariance of matching is shown to be necessary and sufficient for the existence of sensitivity functions that are unique up to multiplication by arbitrary positive real numbers. Examples from auditory and visual psychophysics are discussed.     

A maximum likelihood hierarchical disaggregate model for predicting choices of individuals

The absence of operational disaggregate lexicographic decision models and Tversky's observation that choice behavior is often inconsistent, hierarchical, and context dependent motivate the development of a maximum likelihood hierarchical (MLH) choice model. This new disaggregate choice model requires few assumptions and accommodates the three aspects of choice behavior noted by A. Tversky (1972, Journal of Mathematical Psychology, 9, 341–367). The model has its foundation in a prototype model developed by the authors. Unlike the deterministic prototype, however, MLH is a probabilistic model which generates maximum likelihood estimators of the aggregate “cutoff values.” The model is formulated as a concave programming problem whose solutions are therefore globally optimal. Finally, the model is applied to data from three separate studies where it is demonstrated to have superior performance over the prototype model in its predictive performance.     

Response mode and choice consistency: A test of unfolding theory

Coombs, Donnell, and Kirk (1978. Journal of Experimental Psychology, 4, 497–512), in a study of risk preferences, collected data using both pick $\text{1}\text{3}$ and reject $\text{1}\text{3}$ response modes. Although the preference orders derived from the two response modes were identical, the pick data contained a greater number of inconsistencies than the reject data. In the present study, predictions were derived from unfolding theory (Coombs, 1964. A theory of data. New York: Wiley) regarding the relative consistency of pick and reject response modes. An experiment performed as a test of these predictions supported the unfolding model suggesting that differences in inconsistency between response modes could be attributed to the fineness of the grid of working midpoints imposed upon the choice process by the response mode.     

Item-specific and relational encoding effects in children's recall and recognition memory for words

This study tests the hypothesis that children's deficiency in encoding itemspecific and relational information in episodic events contributes to age differences in recall and recognition. In two experiments, grade school children and college adults were presented with word triplets varying in categorical relatedness. The processing of the item-specific and relational information in the triplets was independently manipulated. Experiment 1 assessed cued recall, and Experiment 2 assessed recognition of both the central target and incidental contextual members of each triplet. The results showed that the processing manipulations had independent and different effects on recall and recognition, on memory for the members of the different kinds of triplets, on the use of the retrieval cues, and on memory for target and incidental words. Developmental differences were found in both recall and recognition, and of both target and incidental words, that varied with triplet type and the processing manipulations and that were attributable to differences in the encoding of item-specific and relational information in the triplets. The discussion contrasts alternative accounts of children's encoding deficiency, and suggests that the distinction between automatic, age-invariant, and strategic age-sensitive encoding processes needs to be redrawn.     

On the measurement of storage and retrieval contributions to memory development

We report two free recall experiments and a cued recall experiment in which a new two-stage model was used to obtain numerical measurements of age changes in various aspects of storage and retrieval. The subjects in all three experiments were 7-year-olds (second graders) and 11-year-olds (sixth graders). The major findings in the free recall experiment were that getting a trace into storage posed less of a problem for elementary schoolers than learning how to get it out on test trials, that retrieval development is more rapid during the elementary school years than storage development, and that the superiority of older children's storage and retrieval abilities tends to become more pronounced as learning progresses. A similar pattern of results was obtained under different conditions in the cued recall experiment.     

Five-month-old infant recall and utilization of temporal organization

The ability of 5-month-old infants to recall temporal information and utilize temporal organization was investigated in two experiments. Infants were trained to fixate a hierarchically structured or an unstructured sequence of stimuli which appeared in four spatial positions. In the first study, the number of infants who demonstrated correct recall through the third serial position of a sequence was significantly better then would occur by chance. In the second study, infants given structured sequences showed a significant increase in the number of correct fixations across trials, and they recalled across serial positions better in structured sequences. Also, accuracy of recall in both studies for the middle serial positions was related to hierarchical organization following 8-unit structured sequence training but was at chance level following unstructured sequence training. Results of both studies were interpreted within a temporal organizational framework: Infants appear to utilize organization within sequences of information.     

The effects of recency and story content on children's moral judgments

Sixteen stories were read to children at ages 4, 7, and 11 years and to college freshmen (n = 24 per age level) to investigate the effects of recency and specific story content on the development of moral reasoning. The stories consisted of either positive or negative intention and either positive or negative consequence in one of four situations: rule breaking, property damage, property damage with peer interaction, or injury to a person. At each age level, half of the subjects heard the stories with the intention first and the consequence second, and half heard them in the reverse order. Analyses confirmed that in general younger children judged on consequence, whereas older children utilized intention, and that on stories containing intentional injury to a person, the younger child took intention into account. Recency effects were evidenced for both the 4- and 7-year-olds. In the 4-year-old group, however, the recency effects failed to override the salience of negative consequence in contexts of positive intention and negative consequence. This suggests that preschool children may respond primarily to the negative aspect of the story, whether intention or consequence.     

Children's understanding of conversational principles

Sixteen preschool, first-, and third-grade children were presented with short stories ending with a verbal statement by a story character. Two alternative ending statements were provided. One alternative violated a postulate (H. P. Grice, 1975, in P. Cole & J. Morgan (Eds.), Syntax and Semantics (Vol. 3), New York: Academic Press) or a reasonable request condition (D. Gordon & G. Lakoff, 1971, Conversational postulates, papers from the seventh regional meeting of the Chicago Linguistic Society, University of Chicago, Department of Linguistics), while the other alternative did not. The child's task was to choose the “funny or silly“ ending, i.e., the violation. Data analysis showed that 100% of the third-graders, 83% of the first-graders, and 19% of the preschoolers performed with significant (P < .02) accuracy. These results suggest that children's understanding of conversational principles improves considerably between preschool and first grade. There were no significant differences among four types of conversational principles examined.