An Interactive Activation Model of the Effect of Context in Perception, Part 1
University of California, San Diego, Center for Human Information Processing, 1980 - Perception - 95 pages
This report is the first part of a two-part series introducing an interactive activation model of context effects in perception. In this part, is developed the model for the perception of letters in words and other contexts and a number of experiments in the recent literature is applied. The model is used to account for the perceptual advantage for letters in words compared to single letters and letters in unrelated strings. In the model, these word-superiority effects are produced by feedback. The visual input produces partial activations of letters, which in turn produce partial activations of words. These activations then produce feedback to the letter level, reinforcing letter sequences which spell words. The model can account for the basic findings on the perception of pronounceable nonwords as well as words. The account is based on the idea that pseudowords can also activate representations of words, even though they do not match any word perfectly. As with word displays, feedback from the activated words reinforces the letters presented, thereby increasing their perceptibility. The model also accounts for the role of masking in determining the magnitude of the various effects, the fact that expectations influence perception of letters in words, and for the fact that effects of contextual constraint and letter cluster frequency are obtained under some conditions and not others.
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Activation functions activation level actually advantage for letters advantage over single assume assumptions bigram frequency blank mask bottom-up Broadbent and Gregory Carnegie Mellon University Carr CCCZZ AA Computer Science constraint items critical letter Department of Psychology depend encoded enemies excitation excitatory experiment feature extraction feature information forced choice forced-choice four-letter word frequency words inhibitory interac interactive activation model Johnston & McClelland laAaN letter mask letter nodes letter position letter to word letters in common letters in pseudowords low constraint MAVE McClelland & Johnston McClelland and Johnston neighbors non-letter Nonletter Mask patterned mask perception of letters performance on words Pittsburgh pronounceable nonwords pseudoword advantage Psychology University readout reinforce resting level Rumelhart share three letters simulation single letters stimuli target letter tion unrelated letter strings value of letter visual conditions visual perception word advantage word inhibition word level word mask word perception words and pseudowords