Letter legibility and visual word recognition

Word recognition performance varies systematically as a function of where the eyes fixate in the word. Performance is maximal with the eye slightly left of the center of the word and decreases drastically to both sides of thisoptimal viewing position. While manipulations of lexical factors have only marginal effects on this phenomenon, previous studies have pointed to a relation between the viewing position effect (VPE) and letter legibility: When letter legibility drops, the VPE becomes more exaggerated. To further investigate this phenomenon, we improved letter legibility by magnifying letter size in a way that was proportional to the distance from fixation (e.g., TABLE). Contrary to what would be expected if the VPE were due to limits of acuity, improving the legibility of letters has only a restricted influence on performance. In particular, for long words, a strong VPE remains even when letter legibility is equalized across eccentricities. The failure to neutralize the VPE is interpreted in terms of perceptual learning: Since normally, because of acuity limitations, the only information available in parafoveal vision concerns low-resolution features of letters; even when magnification provides better information, readers are unable to make use of it.     

CAT: A tool for eliciting knowledge on how to perform procedures

Procedural tasks involve context-sensitive sequences of actions that are performed in pursuit of goals. Procedural knowledge specifies how to do something (e.g., repairing a car) but not how the physical system works (e.g., how the engine works). We have developed a computer program that elicits procedural knowledge from individuals with varying amounts of domain knowledge (ranging from novices to experts) and varying amounts of computer literacy. The tool is called CAT (cognitive analysis tool). CAT is an extension of a class of cognitive models known as GOMS, which stands for goals, operators, methods, and selection rules. The tool guides the user in articulating the goals (and subgoals) the user wants to accomplish, the operators (actions, steps) to accomplish each goal, the alternative methods of accomplishing goals, the conditions in which each method is applied, and exceptional circumstances when goals are suspended and restarted. CAT can be used on most IBMcompatible microcomputers.     

Mapping symbols to response modalities: Interference effects on Stroop-like tasks

Attention, Perception, & Psychophysics - Response compatibility effects were assessed with a Stroop-like task which involved arrow and word stimuli. The subjects were required to respond to one...     

On the Question 'Do Numbers Exist?'

Since we know that there are four prime numbers less than 8 we know that there are numbers. This 'short argument' is correct but it is not an ontological claim or part of philosophy of mathematics. Both realists (Quine) and nominalists (Field) reject the short argument and adopt the idea that the existence of numbers might be posited to explain known mathematical truths. Philosophers operate with a negative conception of what numbers are: they are not in space and time, not related causally to us, not perceivable, etc. This preliminary outlook does not actually characterize a kind of existing thing at all. It creates the atmosphere of weirdness characteristic of both fictionalism and Platonism. Positing things for the sake of explanation makes sense in empirical contexts, but the intelligibility of positing cannot not survive the move to philosophy of mathematics. Modal realism is a model for the unsatisfactory thinking that generates ontological commitment in mathematics.     

Adaptation is automatic

Two experiments were used to test whether selective adaptation for speech occurs automatically or instead requires attentional resources. A control condition demonstrated the usual large identification shifts caused by repeatedly presenting an adapting sound (/wa/, with listeners identifying members of a /ba/-/wa/ test series). Two types of distractor tasks were used: (1) Subjects did a rapid series of arithmetic problems during the adaptation periods (Experiments 1 and 2), or (2) they made a series of rhyming judgments, requiring phonetic coding (Experiment 2). A control experiment (Experiment 3) demonstrated that these tasks normally impose a heavy attentional cost on phonetic processing. Despite this, for both experimental conditions, the observed adaptation effect was just as large as in the control condition. This result indicates that adaptation is automatic, operating at an early, preattentive level. The implications of these results for current models of speech perception are discussed.     

Teaching experimental psychology with on-line computers

The purpose of this paper is to describe the use of on-line computers in the teaching of experimental methodology. Computer models are featured.