Developmental dynamics: toward a biologically plausible evolutionary psychology

There has been a conceptual revolution in the biological sciences over the past several decades. Evidence from genetics, embryology, and developmental biology has converged to offer a more epigenetic, contingent, and dynamic view of how organisms develop. Despite these advances, arguments for the heuristic value of a gene-centered, predeterministic approach to the study of human behavior and development have become increasingly evident in the psychological sciences during this time. In this article, the authors review recent advances in genetics, embryology, and developmental biology that have transformed contemporary developmental and evolutionary theory and explore how these advances challenge gene-centered explanations of human behavior that ignore the complex, highly coordinated system of regulatory dynamics involved in development and evolution.     

Assessing the importance of letter pairs in initial, exterior, and interior positions in reading

Exterior letter pairs (e.g., d--k in dark) play a major role in single-word recognition, but other research (D. Briihl & A. W. Inhoff, 1995) indicates no such role in reading text. This issue was examined by visually degrading letter pairs in three positions in words (initial, exterior, and interior) in text. Each degradation slowed reading rate compared with an undegraded control. However, whereas degrading initial and interior pairs slowed reading rate to a similar extent, degrading exterior pairs slowed reading rate most of all. Moreover, these effects were obtained when letter identities across pair positions varied naturally and when they were matched. The findings suggest that exterior letter pairs play a preferential role in reading, and candidates for this role are discussed.     

Commentary on Steinley and Brusco (2011): recommendations and cautions

I discuss the recommendations and cautions in Steinley and Brusco's (2011) article on the use of finite models to cluster a data set. In their article, much use is made of comparison with the K-means procedure. As noted by researchers for over 30 years, the K-means procedure can be viewed as a special case of finite mixture modeling in which the components are in equal (fixed) proportions and are taken to be normal with a common spherical covariance matrix. In this commentary, I pay particular attention to this link and to the use of normal mixture models with arbitrary component-covariance matrices.     

Incarnation and the Divine Hiddenness Debate

This paper examines the debate that has arisen in connection with J. L. Schellenberg's work on divine hiddenness. It singles out as especially deserving of attention Paul Moser's proposal that the debate distinguish more clearly between classical theism and Hebraic theisms. This worthwhile proposal, I argue, will be unlikely to exert its full potential influence upon the debate unless certain features of Christian incarnation belief are recognized and addressed in connection with it.     

Tremor Frequencies

In an attempt to improve logical reasoning performances, 64 introductory psychology students were randomly assigned to experimental and control groups. The experimental condition involved solving logic syllogisms when the obvious “logical error” was not included as a possible answer. Control subjects solved the same problems with the “logical error” included as a choice. An analysis of variance procedure applied to the subjects' logic pretest-posttest gain scores indicated that the experimental group did significantly better than the control group on invalid principles. The results were discussed in terms of Piaget's theory of logical thinking and the possibility of performance rather than competence problems in adult reasoning. The need to develop more effective instructional techniques to enhance transfer of learning was underscored.     

The instrumental overshadowing effect in pigeons: The role of response bursts

Experiment 1 showed that, when reinforcement is delayed by 0.5 sec for pigeons responding on a variable interval schedule, bursts of responses tend to occur during the delay interval. Such bursts are not seen when a signal (illumination of the houselight) fills the delay interval. The higher overall response rate seen with the unsignalled procedure may, therefore, be a consequence of the differential reinforcement of response bursts. Experiment 2 found, however, that the difference between the signalled and unsignalled conditions remained when the signal used was one that was relatively ineffective in suppressing bursts. Experiment 3 found that in some conditions the unsignalled procedure will generate a higher response rate than the signalled procedure even when there is no delay of reinforcement and thus little opportunity for differential reinforcement of response bursts. It is argued that, in addition to any contribution from the differential reinforcement of bursts, these effects also reflect the overshadowing of a response—reinforcer association by the signal that is a more valid predictor of the reinforcer.