The indifference argument

I argue against motivational internalism. First I recharacterise the issue over moral motivation. Second I describe the indifference argument against motivation internalism. Third I consider appeals to irrationality that are often made in the face of this argument, and I show that they are ineffective. Lastly, I draw the motivational externalist conclusion and reflect on the nature of the issue. Thanks for helpful comments to Philippa Foot and especially to an anonymous referee. Distant ancestors of the paper were given as talks in an American Philosophical Association conference in New Orleans and in St Andrews.     

Psychology and the End of History: A Critique and a Proposal for the Psychology of Social Categorization

This paper suggests that self-categories provide the basis for political action, that those who wish to organize political activity do so through the ways in which they construct self-categories, and that political domination may be achieved through reifying social categories and therefore denying alternative ways of social being. Hence, the way in which social psychology approaches the matter of self-categorization provides a touchstone for its politics. To the extent that we too take categories for granted, we are in danger of supporting conservative and undemocratic politics. The only way to eschew tendencies toward reification within social psychology is to add a historical dimension to our own analysis of self-categorical processes.     

Taxometric analysis of fuzzy categories: a Monte Carlo study

A small Monte Carlo study examined the performance of a form of taxometric analysis (the MAXCOV procedure) with fuzzy data sets. These combine taxonic (categorical) and nontaxonic (continuous) features, containing a subset of casts with intermediate degrees of category membership. Fuzzy data sets tended to yield taxonic findings on plot inspection and two popular consistency tests, even when the degree of fuzziness, i.e., the proportion of intermediate cases, was large. These results suggest that fuzzy categories represent a source of pseudotaxonic inferences, if on is understood in the usual binary, "either-or" fashion. This in turn implies that dichotomous causes cannot be confidently inferred when taxometric analyses yield apparently taxonic findings.     

Childhood Psychological Trauma and First‐Year College Students' Substance Dependence

First‐year college students (N= 143) completed the Substance Abuse Subtle Screening Inventory‐3 and a questionnaire about childhood traumatic experiences. As the number of traumatic experiences increases, so does the likelihood of substance use in college.     

Prefrontal cortex and the mediation of proactive interference in working memory

Mediating proactive interference (PI), the deleterious effect of antecedent information on current memory representations, is believed to be a key function of prefrontal cortex (PFC). Item-specific PI results when an invalid probe matches a memorandum from the preceding trial; item-nonspecific PI is produced by the accumulation of no-longer-relevant items from previous trials. We tested the hypothesis that these two types of PI are mediated by common PFC-based processes with an fMRI study of a delayed-recognition task designed to produce both types of PI. Our results indicated that the fMRI correlates of both effects were restricted both to Brodmann’s area 45 in the left hemisphere and to the memory probe epoch of the trial. These results suggest that a unification of the literatures and approaches that have independently studied these phenomena might offer a fruitful new perspective from which to study the relations between working memory, executive control, and the PFC.     

No-go trials can modulate switch cost by interfering with effects of task preparation

It has recently been shown that the cost associated with switching tasks is eliminated following ‘no-go’ trials, in which response selection is not completed, suggesting that the switch cost depends on response selection. However, no-go trials may also affect switch costs by interfering with the effects of task preparation that precede response selection. To test this hypothesis we evaluated switch costs following standard go trials with those following two types of non-response trials: no-go trials, for which a stimulus is presented that indicates no response should be made (Experiment 1); and cue-only trials in which no stimulus is presented following the task cue (Experiment 2). We hypothesized that eliminating no-go stimuli would reveal effects of task preparation on the switch cost in cue-only trials. We found no switch cost following no-go trials (Experiment 1), but a reliable switch cost in cue-only trials (i.e., when no-go stimuli were removed; Experiment 2). We conclude that no-go trials can modulate the switch cost, independent of their effect on response selection, by interfering with task preparation, and that the effects of task preparation on switch cost are more directly assessed by cue-only trials.     

The generalized universal law of generalization

It has been argued by Shepard that there is a robust psychological law that relates the distance between a pair of items in psychological space and the probability that they will be perceived as similar. Specifically, this probability is a negative exponential function of the distance between the pair of items. In experimental contexts, distance is typically defined in terms of a multidimensional space—but this assumption seems unlikely to hold for complex stimuli. We show that, nonetheless, the Universal Law of Generalization can be derived in the more complex setting of arbitrary stimuli, using a much more universal measure of distance. This universal distance is defined as the length of the shortest program that transforms the representations of the two items of interest into one another: The algorithmic information distance. It is universal in the sense that it minorizes every computable distance: It is the smallest computable distance. We show that the Universal Law of Generalization holds with probability going to one—provided the probabilities concerned are computable. We also give a mathematically more appealing form of the Universal Law.