Conceptual encoding and locus of the Stroop effect

Subjects reacted to coloured season and month names by naming the season associated with the print colour of the word, or by naming the season opposite to the one associated with the print colour. Reactions were facilitated in both tasks when the word on the display named the season associated with the colour or was a month belonging to that season. Opposite season naming was not facilitated when the word named the response which the subject made. A comparable effect of print colour was found when subjects reacted to season names by naming the colour associated with the name, or with its opposite. These results suggest that Stroop congruity and interference effects occur during conceptual encoding, and not during response production.     

Evaluation of a continuing computer conference on simulation

A 20-day computer conference was held in preparation for a face-to-face meeting to produce a computer simulation. The conferencing resulted in the generation of seven different models and was excellent preparation for the subsequent meeting. Computer conferencing appears to hold great value for faculty development in a period of reduced faculty mobility.     

Book reviews

Wyer, Robert S., Jr. Cognitive Organization and Change : an Information Processing Approach. Potomac, Maryland: Lawrence Erlbaum Associates. 1974. Pp. 502. £10.50.

Egan, J. P. Signal Detection Theory and ROC Analysis. New York: Academic Press. 1975. Pp. 277. £9.75. ISBN

Aldis, O. Play-Fighting. New York: Academic Press. 1975. Pp. 319. £8.75.

Warburton, D. M. Brain Behaviour and Drugs. London: John Wiley. 1975. Pp. 280. £6.95. ISBN 0471 91991 8.

Grieve, D. W., Miller, D., Mitchelson, D., Paul, J. and Smith, A. J. Techniques for the Analysis of Human Movement. London: Lepus Books. 1975. Pp. 177. £5.50.     

A note on computing Louis’ observed information matrix identity for IRT and cognitive diagnostic models

Using Louis’ formula, it is possible to obtain the observed information matrix and the corresponding large-sample standard error estimates after the expectation–maximization (EM) algorithm has converged. However, Louis’ formula is commonly de-emphasized due to its relatively complex integration representation, particularly when studying latent variable models. This paper provides a holistic overview that demonstrates how Louis’ formula can be applied efficiently to item response theory (IRT) models and other popular latent variable models, such as cognitive diagnostic models (CDMs). After presenting the algebraic components required for Louis’ formula, two real data analyses, with accompanying numerical illustrations, are presented. Next, a Monte Carlo simulation is presented to compare the computational efficiency of Louis’ formula with previously existing methods. Results from these presentations suggest that Louis’ formula should be adopted as a standard method when computing the observed information matrix for IRT models and CDMs fitted with the EM algorithm due to its computational efficiency and flexibility.     

Social value orientations and negotiator outcomes

Social value orientations (SVOs) are known to influence individual behaviour in outcome interdependent settings. By extending these findings to negotiation, this research investigates the relationship between own and partners' SVOs, negotiator strategies and outcomes. Results showed that cooperators, competitors and individualists could be distinguished in terms of initial demands and concessions. Competitors made higher initial demands and larger concessions than individualists or cooperators, suggesting that their ability to maximize outcome differences rests on whether structural features are congruent with this goal. The principal finding of this research was the demonstration that own and partners' SVO interact to determine outcomes. Results showed that the three SVO groups differed in terms of context sensitivity: competitor outcomes were invariant across partners; individualists achieved poor outcomes in negotiations with cooperators and, reciprocally, cooperators attained high outcomes in negotiations with individualists. Additionally, individualist outcomes worsened in their last negotiation, while those of cooperators differed as a function of role and partner's SVO. These results suggest that although the information used by individualists and cooperators differs, for both groups the cognitive representation of negotiations is a further factor influencing their outcomes.