Studies of letter identification using qualitative error analysis: effects of speed stress, tachistoscopic presentation, and word context

In Experiment 1 subjects named letters under a response deadline chosen so that an appreciable number of errors would be produced. The stimulus confusions were analyzed via the same mathematical models of stimulus recognition that have been applied to the confusion matrices generated in tachistoscopic experiments. Both the Luce choice model and the informed guessing model (a new model having a simple and elegant process interpretation) provided excellent fits to the data. The parameter values of the informed guessing model changed in logical and interpretable ways with changes in the response deadline. In Experiment 2 a direct comparison was made of the types of errors produced in the data-limited tachistoscopic situation and the resource-limited response deadline situation. It was found that, relative to the response deadline task, identification in the tachistoscopic task is much more likely to be based on partial information. In Experiments 3 and 4 the same research methodology was applied to the problem of the effect of a word context on letter perception. The methodology allowed this problem to be addressed in the context of both response deadline and tachistoscopic tasks. Several advantages of the methodology for investigating other issues of interest to cognitive psychologists are discussed.