Theoretical and methodological analysis of partial knowledge

A theory of partial knowledge is proposed as an explanation of cognitive development, and methods are described for testing the theory. The theory consists of three structure-process pairs, each of which postulates a type of cognitive structure and a developmental process specific to that type. In restricted knowledge, a unitary algorithm is the cognitive structure, and amendment is the developmental process. In variable sampling, a structure of unitary substitutes is paired with a process of selection. In variable integration, modular components are paired with self-monitoring. Methods for testing the theory form a sequence of mathematical models. The first model in the sequence, called a model of double assessment, is described both verbally and mathematically. Other models in the sequence are described verbally with reference to other articles for the formal mathematics. Also described are some nonmathematical methods to be used as sequels to the double assessment model.     

Less is more: Two- and three-dimensional graphics for data display

Psychologists tend to rely on a few simple graphs for presenting their results. The line chart, scatterplot, and profile plot have their uses, but there are new methods for displaying data which can reveal more. This paper shows several univariate and multivariate displays which can be created on a desktop computer and which reveal the distribution of the data they summarize.     

Book reviews

Paul Ricoeur. Freud and Philosophy: An Essay On Interpretation (trans. Denis Savage). New Haven: Yale University Press, 1970. Pp. 1–551. Indexed. $15.00.

Keith Campbell. Body and Mind. Garden City, N.Y.: Doubleday, 1970. Pp. vi, 150. Indexed. $1.45 (paper).

D. J. O'Connor. Free Will. Garden City, N.Y.: Doubleday Anchor Books, 1971. Pp. 1–150. Indexed. $1.45.

Dwight van de Vate, Jr. (ed.). Persons, Privacy, and Feeling: Essays in the Philosophy of Mind. Memphis: Memphis State University Press, 1970. Pp. vii, 140. Indexed. $5.00.     

Distractor ratio and grouping processes in visual conjunction search.

According to feature integration theory, conjunction search is conducted via a serial self-terminating search. However, effects attributed to search processes operating on the entire display may actually reflect search restricted to elements defined by a single feature. In experiment 1 this question is addressed in a reaction-time (RT) paradigm by varying distractor ratios within an array of fixed size. For trials in which the target was present in the array, RT functions were roughly symmetric, the shortest RTs being for extreme distractor ratios, and the longest RTs being for arrays in which there were an equal number of each distractor type. This result is superficially consistent with Zohary and Hochstein's interpretation that subjects search for only one distractor type and are able to switch search strategy from trial to trial. However, negative-trial data from experiment 1 case doubt on this interpretation. In experiment 2 the possible role of 'pop out' and of distractor grouping in visual conjunction search is investigated. Results of experiment 2 suggest that grouping may play a more important role than does distractor ratio, and point to the importance of the spatial layout of the target and of the distractor elements in visual conjunction search. Results of experiment 2 also provide clear evidence that groups of spatially adjacent homogeneous elements may be processed as a unit.