While I am first and foremost a university lecturer, I do try to keep my hand in the research game. Here are my research interests:
I have a general interest in mathematical psychology, cognitive modelling, psychophysics, and measurement and scaling. I am particularly interested in models of judgement and decision-making.
I also goof off by building computer models of various processes. For example, this model of intolerance in a society of "dudes".
Whenever possible, I encourage my independent research project and honours thesis students to develop computer models of their hypothesized systems.
I've also been considering how changes in decisional complexity affects decision-making processes. For example, a series of six n-alternative forced-choice (nAFC, where 2<=n<=4) sensory-based decision-making experiments (to see a nifty example of what I'm talking about, click HERE). I used these data to develop a comprehensive, computer-based, evidence accrual model of nAFC decision-making.
I've also used the classic decision/confidence experimental paradigm to illustrate the limits of anchoring effects. In four experiments involving a sensory detection task, participants first made a relative confidence judgement by deciding whether they were more or less confident in the correctness of their decision than an anchor value. Subsequently, they expressed an absolute level of confidence. In two of these experiments, the relative confidence anchor values represented the midpoints between the absolute confidence scale values, which were either explicitly numeric or non-numeric semantic representations of magnitude. In two other experiments, the anchor values were drawn from a modally different scale than was used to express the absolute confidence (i.e., non-numeric and numeric, respectively, or vice versa). Regardless of the nature of the anchors, the mean confidence ratings revealed anchoring effects only when the relative and absolute confidence values were drawn from identical scales. Together, the results of these four experiments limit the conditions under which both numeric and semantic priming would be expected to lead to anchoring effects (Carroll, Petrusic, & Leth-Steensen; 2009).
I've also been attempting to ascertain the locus and time course of confidence processing within sensory-based decision-making tasks. I conducted two experiments, one a signal detection task and the other a line-length discrimination task. In each experiment, in one of three blocks of trials, participants rated their confidence in the accuracy of each decision by selecting one of six confidence categories. In a second block participants never rendered confidence. In a third block participants always expected to have to render confidence, but were instructed not to do so if a tone sounded. The tone sounded on 50% of the trials at times varying from 100 to 500 ms following stimulus presentation. In each experiment, primary decision response times increased whenever confidence was rendered. Importantly, in the stop-confidence processing signalled task, primary decision response times increased linearly as the time between the stimulus presentation and the stop-confidence signal increased. These findings are clear in implicating both a decisional and post-decisional locus for the basis of confidence and that confidence processing is not ballistic and can be stopped.