Case-control comparisons are a class of statistical tests allowing researchers to compare single cases to populations estimated from a sample. Such tests have wide potential utility, but historically have been applied mostly in the fields of cognitive and clinical neuropsychology, to infer whether individuals have suffered significant cognitive changes as the consequence of a brain lesion. One may wish to estimate whether that individual has abnormally low performance on some cognitive ability, or if one cognitive ability is abnormally discrepant with respect to another cognitive ability. John Crawford, Paul Garthwaite and colleagues have developed several related methods to statistically test for abnormality on a single variate and abnormality of the difference between two variates when a single case is compared to a small sample, while controlling the Type I error rate (
Researchers and clinicians in neuropsychology often compare individual patients against healthy control samples, to quantify evidence for cognitive-behavioural deficits and dissociations. Statistical methods for these comparisons have been developed that control Type I (false positive) errors effectively. However, remarkably little attention has been given to the power of these tests. In this practical primer, we describe, in minimally technical terms, the origins and limits of power for case-control comparisons. We argue that power calculations can play useful roles in single-case study design and interpretation, and we make suggestions for optimising power in practice. As well as providing figures, tables and tools for estimating the power of case-control comparisons, we hope to assist researchers in setting realistic expectations for what such tests can achieve in general.
This article adapts an existing experimental protocol for assessing individuals’ ability to transfer knowledge across instrumental and pavlovian learning stages. The protocol (
Transfer of Control
using differential outcomes learning) is adapted to fit social contexts wherein the pavlovian learning phase is modulated so that individuals are able to observe, and potentially learn from, the stimulus associated with reinforcing outcomes presented to another (observable) individual. Transfer of Control concerns participants combining knowledge of learned instrumental and pavlovian (stimulus, response, outcome) associations in order to ground the learning of new associations. The article describes the theoretical and procedural underpinnings of a novel
Social Transfer of Control
methodology. The use of such a methodology is two-fold: i) to serve as a guide to researchers interested in evaluating how individuals can learn from others in a partially observable setting, i.e. when behavioural and reinforcing outcome information is hidden, and bring to bear this knowledge on their own instrumental decision making; ii), to facilitate investigation of the routes of cognitive and emotional empathy, with potential applications for educational and clinical settings.
Three stage
Transfer of Control
behavioural methodology is adapted to include a social (pavlovian) learning stage.
Hypotheses can be tested that concern learning rewarding instrumental responses achieved by observation of others’ emotionally expressive reactions to differentially rewarding outcomes.
Methodological and validation considerations for evaluating the above are presented
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