Assessing the predictions from Posner's theory of phasic alertness using data from Los and Schut (2008).

Alertness has been construed as one of three fundamental components of attention. When generated by a warning signal, phasic changes in alertness ubiquitously decrease reaction time. But how does it do so? Based on earlier findings, in 1975, Posner proposed a theory of phasic alertness with two postulates: (i) phasic alertness does not affect the accumulation of information; (ii) phasic alertness accelerates when a response based on the accumulating information will be generated. When targets are continuously presented, this theory predicts that alertness will reduce reaction at the expense of an increase in errors-that is, generate a speed-accuracy trade-off. Los and Schut, Cognitive Psychology, 57, 20-55, (2008), while endorsing Posner's theory, claimed to have failed to replicated the tell-tale trade-off reported by Posner et al. Memory and Cognition, 1, 2-12, (1973, Experiment 1). The primary goal of this commentary was to use all the data from Los and Schut to see if the predicted speed-accuracy trade-off would be verified or not. With the increased power, it was confirmed that the conditions that benefited the most in reaction time from alertness also had higher error rates. It is noteworthy that recent studies have generated replications and extensions of the methods and findings of Posner et al; thus, it appears that the empirical pattern predicted by Posner's theory of phasic alertness is relatively robust.