Homographs
and Context Effects on Visual Target Information Processing
V.B. Dauphin & C. Izawa |
In
an attempt to control the initial stage of perceptual filtering or
feature extraction, 7 homographs or ambiguous characters were generated,
each having identical physical attributes and thus identical retinal
stimulations, may it be processed as a letter or a digit. Expressed
in a block style, e.g. Letter 0 (oh) was exactly the same as Digit
0 (zero) in all physical dimensions. Each homograph (target) was
presented among the two unambiguous nontargets, consisting of letters
only (letter context), a letter and a digit (mixed context), and
digits only (digit context). In spite of the strong digit bias inherent
to the block style representation of characters, the context did
exert large effects, presumed to occur in a later stage of information
processing, i.e. the decision or interpretation stage. Context effects
were generally greater with the whole report (all three characters
were reported) than with the cued report (only the cued target was
reported). The attention factor, as revealed by the differences between
whole and cued reports, seems generally large with the letter context
but negligible with the digit context. Differential context effects
may, in part, be attributable to familiarity. Physical properties
of nontargets as well as those of targets seem to control visual
information processing to a substantial degree.
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