TreeBUGS: An R package for hierarchical multinomial-processing-tree modeling

Multinomial processing tree (MPT) models are a class of measurement models that account for categorical data by assuming a finite number of underlying cognitive processes. Traditionally, data are aggregated across participants and analyzed under the assumption of independently and identically distributed observations. Hierarchical Bayesian extensions of MPT models explicitly account for participant heterogeneity by assuming that the individual parameters follow a continuous hierarchical distribution. We provide an accessible introduction to hierarchical MPT modeling and present the user-friendly and comprehensive R package TreeBUGS, which implements the two most important hierarchical MPT approaches for participant heterogeneity—the beta-MPT approach (Smith & Batchelder, Journal of Mathematical Psychology 54:167-183, 2010) and the latent-trait MPT approach (Klauer, Psychometrika 75:70-98, 2010). TreeBUGS reads standard MPT model files and obtains Markov-chain Monte Carlo samples that approximate the posterior distribution. The functionality and output are tailored to the specific needs of MPT modelers and provide tests for the homogeneity of items and participants, individual and group parameter estimates, fit statistics, and within- and between-subjects comparisons, as well as goodness-of-fit and summary plots. We also propose and implement novel statistical extensions to include continuous and discrete predictors (as either fixed or random effects) in the latent-trait MPT model.     

Object-centred spatial reference in 4-month-old infants

An appreciation of object-centred spatial relations involves representing a 'within-object' spatial relation across changes in the object orientation. This representational ability is important in adult object recognition [Biederman, I. (1987). Recognition-by-components: A theory of human image understanding. Psychological Review, 94, 115-147; Marr, D., & Nishihara, H. K. (1978). Representation and recognition of the spatial organisation of three-dimensional structure. Proceedings of the Royal Society of London, Series B (Biological Sciences), 200, 269-294; Tarr, M. J., & Pinker, S. (1990). When does human object recognition use a viewer-centred reference frame? Psychological Science, 1, 253-256] and is also thought to be a fundamental component of the mature object concept [Piaget, J. (1954). The Construction of Reality in the Child. Routledge & Kegan-Paul: London, UK. (Originally published in French in 1937)]. An experiment is reported in which eighteen 4-month-old infants were familiarised to a specific spatial relation within an object, across six different orientations of the object. On subsequent test trials the object was presented to the infants in an entirely novel orientation. Between successive test trials the within-object spatial relation was alternated between novel and familiar. The infants demonstrated significant sensitivity of their looking to both the novelty of the stimuli and the order in which novel and familiar stimuli were presented. It is concluded that by 4 months of age infants are able to form object-centred spatial frames of reference. These findings are discussed in the light of our current understanding of the development of object representation during infancy.     

On the determinants of implicit evaluations: When the present weighs more than the past

It is often assumed that implicit evaluations are influenced by early childhood experiences, whereas explicit evaluations reflect recent experiences. However, previous findings supporting this assumption remain ambiguous as to whether the differential effects of early versus recent experiences are driven by their temporal distance or their affective versus cognitive nature. Controlling for affectivity by using a predominantly affective attitude object (i.e., religion), the present study found that both implicit and explicit evaluations were related to recent, but not early, experiences. This pattern consistently emerged for self-reported experiences as well as independent reports from parents. Moreover, the relation of recent experiences to one type of evaluation remained significant after controlling for the respective other type of evaluation, suggesting that recent experiences influenced implicit and explicit evaluations independently. Implications for attitudinal dissociations and processes of attitude change are discussed.     

Selecting explanations from causal chains: Do statistical principles explain preferences for voluntary causes?

We investigate whether people prefer voluntary causes to physical causes in unfolding causal chains and whether statistical (covariation, sufficiency) principles can predict how people select explanations. Experiment 1 shows that while people tend to prefer a proximal (more recent) cause in chains of unfolding physical events, causality is traced through the proximal cause to an underlying distal (less recent) cause when that cause is a human action. Experiment 2 shows that causal preference is more strongly correlated with judgements of sufficiency and conditionalised sufficiency than with covariation or conditionalised covariation. In addition, sufficiency judgements are partial mediators of the effect of type of distal cause (voluntary or physical) on causal preference. The preference for voluntary causes to physical causes corroborates findings from social psychology, cognitive neuroscience and jurisprudence that emphasise the primacy of intentions in causal attribution processes. Copyright © 2009 John Wiley & Sons, Ltd.     

Striving for difference: On the spontaneous preference for ingroup members who maximize ingroup positive distinctiveness

Previous research demonstrated that individuals spontaneously prefer ingroup members who display ingroup favoritism rather than egalitarian behaviors (Castelli, Tomelleri, & Zogmaister, 2008). In the current work, we explored what specific strategies toward ingroup favoritism are spontaneously preferred. Results from four studies showed that ingroup members who made it possible for the ingroup to achieve a positive intergroup differentiation were preferred as compared to ingroup members who maximized the absolute gain for the ingroup. Study 5 further demonstrated that in the search for positive distinctiveness people are sensitive to the ratio between the gains of the ingroup and outgroup. Study 6 ruled out a possible alternative explanation. Overall, the current findings indicate that group members who set the difference from an outgroup elicit the most positive spontaneous responses demonstrating that the search for a positive intergroup distinctiveness automatically affects intragroup perception. Copyright © 2010 John Wiley & Sons, Ltd.