Isolating visual units in the perception of words and nonwords

Abstract

In three experiments, reaction times for same-different judgments were obtained for pairs of words, pronounceable nonwords (pseudcwords), and unpronounceable nonwords. The stimulus strings were printed either in a single letter case or in one of several mixtures of upper-and lowercase letters. In Experiment 1, the stimuli were common one-and two-syllable words; in Experiment 2, the stimuli included both words and pseudowords; and in Experiment 3, words, pseudowords, and nonwords were used. The functional visual units for each string type were inferred from the effects that the number and placement of letter case transitions had on same reaction time judgments. The evidence indicated a preference to encode strings in terms of multiletter perceptual units if they are present in the string. The data also suggested that whole words can be used as functional visual units, although the ex~t of their use depends on contextual parameters such as knowledge that a word will be presented"For over a century, the question of how we perceive letter strings, and words in particular, has both fascinated and troubled experimental psychologists. For some, it has seemed obvious that we perceive individual letters and assemble a word from them. Others have maintained that we perceive whole words directly, while still others have postulated intermediate perceptual units such as spelling patterns, syllables, and vocalic center groups (Smith & Spoehr, 1974). To the casual observer it must seem perplexing that psychologists have been unable to resolve such a seemingly simple issue in favor of one or another alternative. However, many investigations have resulted in conflicting indications of what constitutes the appropriate visual unit in word perception.It is understandable that there is reluctance to abandon the attempt to identify a single perceptual unit. If more than one perceptual unit is hypothesized, then an adequate model must specify which units exist and how these units are coordinated. The model to which we subscribe is a process model similar to the one proposed by LaBerge and Samuels

The role of syllabic and orthographic properties of letter cues in solving word fragments

“…The data confirm a conclusion reached by some researchers in the area of visual word recognition (e.g., Seidenberg, 1987;Taylor et al, 1977)-multiletter clusters that mayor may not be syllables in a word sometimes act as the sublexical units in a word. But what cluster of letters constitutes the sublexical units in a word?…”

“…For instance, on tasks requiring a same-different judgment for two simultaneously presented words, the effect of increasing the number of syllables in the pair of words that had to be compared had no consistent effect on response time (Klapp, 1971;Taylor, Miller, & Juola, 1977). Similar inconsistencies have been reported with word-naming and lexical decision tasks.…”

Is there a lexicality component in the word superiority effect?

“…Moreover, Manelis (1974) specifically compared blocking and randomizing within a single study and found that, with randomization of the lexicality factor, its facilitatory effect was either reduced or eliminated. In a related manipulation, Taylor, Miller, and Juola (1977) varied the relative proportions of words and pseudowords within a randomized design using the samedifferent task. The lexicality effect for "same" decisions appears to be unaffected by this manipulation, but the lexical facilitation of "different" decisions increased with increases in the proportion of stimuli that were real words.…”

Visual search for letters in intact and mixed-case words and nonwords

“…If the use of orthographic redundancy is the key to word-superiority effects, word advantages over nonwords in perception should be the same for intact and mixed-case displays. In fact, same-different judgment times for simultaneously presented letter strings are slowed more for words than for nonwords when their letters are printed in mixed case relative to intact upper-or lowercase form (Bruder, 1978;Pollatsek , Well,& Schindler,1975 ;Taylor, Miller, & Juola , 1977). Apparently, the mixing of letter cases in words disrupts the visual familiarity of multiletter units and increases the likelihood that they must be processed letter This research was supported by Biomedical Sciences Grant RR~7037 to the University of Kansas, National Science Foundation Grant BMS74-12801.…”

“…Both short-term retention and comparison processes could be facilitated by the use of familiar letter-cluster or whole -word units rather than individual letters. In fact, Bruder (1978) has argued that the word-superiority effect in the simultaneous matching task is due primarily to the use of familiar letter-cluster units to facilitate the comparison stage of processing, whereas Taylor et al (1977) argued from similar data that at least part of the word advantage is due to encoding differences between words and nonwords.…”