Prediction in the Aging Brain: Merging Cognitive, Neurological, and Evolutionary Perspectives.

Although the aging brain is typically characterized by declines in a variety of cognitive functions, there has been growing attention to cognitive functions that may stabilize or improve with age. We integrate evidence from behavioral, computational, and neurological domains under the hypothesis that over the life span the brain becomes more effective at predicting (i.e., utilizing knowledge) compared to learning. Moving beyond mere description of the empirical literature-with the aim of arriving at a deeper understanding of cognitive aging-we provide potential explanations for a learning-to-prediction shift based on evolutionary models and principles of senescence and plasticity. The proposed explanations explore whether the occurrence of a learning-to-prediction shift can be explained by (changes in) the fitness effects of learning and prediction over the life span. Prediction may optimize (a) the allocation of limited resources across the life span, and/or (b) late-life knowledge transfer (social learning). Alternatively, late-life prediction may reflect a slower decline in prediction compared to learning. By discussing these hypotheses, we aim to provide a foundation for an integrative neurocognitive-evolutionary perspective on aging and to stimulate further theoretical and empirical work.

Meaningful change definitions: sample size planning for experimental intervention research.

Experimental tests of interventions need to have sufficient sample size to constitute a robust test of the intervention's effectiveness with reasonable precision and power. To estimate the required sample size adequately, researchers are required to specify an effect size. But what effect size should be used to plan the required sample size? Various inroads into selecting the a priori effect size have been suggested in the literature-including using conventions, prior research, and theoretical or practical importance. In this paper, we first discuss problems with some of the proposed methods of selecting the effect size for study planning. We then lay out a method for intervention researchers that provides a way out of many of these problems. The proposed method requires setting a meaningful change definition, it is specifically suited for applied researchers interested in planning tests of intervention effectiveness. We provide a hands-on walk through of the method and provide easy-to-use R functions to implement it.

Measuring the Unmeasurable : The Psychometrics of Life History Strategy.

Within evolutionary biology, life-history theory is used to explain cross-species differences in allocation strategies regarding reproduction, maturation, and survival. Behavioral scientists have recently begun to conceptualize such strategies as a within-species individual characteristic that is predictive of behavior. Although life history theory provides an important framework for behavioral scientists, the psychometric approach to life-history strategy measurement-as operationalized by K-factors-involves conceptual entanglements. We argue that current psychometric approaches attempting to identify K-factors are based on an unwarranted conflation of functional descriptions and proximate mechanisms-a conceptual mix-up that may generate unviable hypotheses and invites misinterpretation of empirical findings. The assumptions underlying generic psychometric methodology do not allow measurement of functionally defined variables; rather these methods are confined to Mayr's proximate causal realm. We therefore conclude that K-factor scales lack validity, and that life history strategy cannot be identified with psychometrics as usual. To align theory with methodology, suggestions for alternative methods and new avenues are proposed.

Sex, germs, and health: pathogen-avoidance motives and health-protective behaviour.

OBJECTIVE: Recent work suggests that the psychology of pathogen-avoidance has wide-reaching effects on how people interact with the world. These processes - part of what has been referred to as the behavioural immune system - are, in a way, our 'evolved' health psychology. However, scholars have scarcely investigated how the behavioural immune system relates to health-protective behaviours. The current research attempts to fill this gap. DESIGN: Across two cross-sectional studies (N = 386 and 470, respectively), we examined the relationship between pathogen-avoidance motives and health-protective behaviour. OUTCOME MEASURES: The studies used self-reported measures of attitude and intention as indicators of health-protective behaviour. RESULTS: Data collected in Study 1 revealed that pathogen-avoidance motivation related to participants' attitude and intention towards sexually transmitted infections screening. High levels of pathogen-avoidance motivation were also related to having had fewer sexual partners, which partially mediated the effect of pathogen-avoidance variables on testing motivation. Study 2 extended these findings by showing moderate associations between pathogen-avoidance motivation and a broad range of health-protective behaviours, including but not limited to pathogen-related health concerns. CONCLUSION: We argue that understanding and targeting pathogen-avoidance psychology can add novel and important understanding of health-protective behaviour.