A dual-task analysis of detection accuracy for the case of high target-distractor similarity: Further evidence for independent processing

Previous studies of visual detection performance indicate that perceptual span has a negligible effect on detection accuracy; hence, previous results suggest that individual characters within a multielement array are perceived independently. In this study, additional experimental factors were examined in order to determine whether conditions exist in which perceptual span influences detection performance: targets and distractors were chosen to be maximally similar, and detection accuracy was studied in relation to display size, target redundancy, and homogeneity of distractor characters. To test for perceptual span effects, a three-state model was proposed which incorporates the assumption that individual characters are perceived independently. The model may be applied to (a) both yes-no and forced-choice tasks, and (b) the case when effects of display characteristics differ for response alternatives. Predictions based on the three-state model agree satisfactorily with observed proportions. Moreover, interactions between display characteristics and response alternatives accord well with model predictions, and accuracy differences between subjects are consistent with individual differences in model parameters. The results provide further evidence for the independence assumption and illustrate additional conditions for which perceptual span has a negligible effect on detection accuracy.     

Phonemic behavior of aphasic patients with posterior cerebral lesions

The investigation analyzed the phonemic paraphasic errors of 10 asphasic patients with posterior cerebral lesions. The results indicated that paraphasic speech is characterized by complex confusions, often occurring at the ends of words and often involving phonemic transpositions. Many of the unusual and unexpected phonemic errors appeared to be due to simultaneous semantic and phonologic confusions.     

Meaning and learning: Response to Moerk

In response to Moerk (1986, Developmental Review, 6, 365–385) the following points are discussed: (a) Semantic and conceptual development must be conceived in terms of systems that undergo developmental change, (b) Objects are viewed as embedded in events and as being conceptualized first within a syntagmatic and later a paradigmatic system, (c) While the nature of the input to the child is important, its effects cannot be considered independently of the state of the child's conceptual and linguistic system. (d) The neurological considerations discussed by Moerk are not relevant to the particular developmental issues discussed in my book.     

Accessibilism and the Challenge from Implicit Bias

Recent research in social psychology suggests that many beliefs are formed as a result of implicit biases in favour of members of certain groups and against members of other groups. This article argues that beliefs of this sort present a counterexample to accessibilism in epistemology because the position cannot account for how the epistemic status of a belief that is the result of an implicit bias can differ from that of a counterpart belief that is the result of an unbiased response to the available evidence.