The effects of frequency, repetition and stimulus quality in visual word recognition

This paper describes a lexical decision experiment, which examined the relation between word frequency, repetition and stimulus quality. In contrast to earlier studies (Stanners, Jastrzembski and Westbrook, 1975; Becker and Killion, 1977), frequency and stimulus quality were found to interact. The implications of this result for models of word recognition are discussed within the framework of Becker's verification model.     

Modulating semantic feedback in visual word recognition

According to the interactive activation framework proposed by McClelland and Rumelhart (1981), activation spreads both forward and backward between some levels of representation during visual word recognition. An important boundary condition, however, is that the spread of activation from lower to higher levels can be prevented (e.g., explicit letter processing during prime processing eliminates the well-documented semantic priming effect). Can the spread of activation from higher to lower levels also be prevented? This question was addressed with a choice task procedure in which subjects read a prime word and then responded to a target, performing either lexical decision or letter search depending on the color of the target. A semantic context effect was observed in lexical decision, providing evidence of semantic-level activation. In contrast, there was no semantic context effect in the letter search task, despite evidence of lexical involvement: Words were searched faster than nonwords. Further evidence of lexical involvement in the letter search task appeared in Experiment 2 in the form of greater identity priming for words than for nonwords. The results of these experiments are consistent with the conclusion that feedback from the semantic level to the lexical level can be blocked. Hence, between-level activation blocks can be instantiated in both bottom-up and top-down directions.     

Automatic semantic feedback during visual word recognition

Four experiments were conducted to determine whether semantic feedback spreads to orthographic and/or phonological representations during visual word recognition and whether such feedback occurs automatically. Three types of prime-target word pairs were used within the mediated-priming paradigm: (1) homophonically mediated (e.g., frog-[toad]-towed), (2) orthographically mediated (e.g., frog-[toad]-told), and (3) associatively related (e.g., frog-toad). Using both brief (53 msec; Experiment 1) and long (413 msec; Experiment 3) prime exposure durations, significant facilitatory-priming effects were found in the response time data with orthographically, but not homophonically, mediated prime-target word pairs. When the prime exposure duration was shortened to 33 msec in Experiment 4, however, facilitatory priming was absent with both orthographically and homophonically mediated word pairs. In addition, with a brief (53-msec) prime exposure duration, direct-priming effects were found with associatively (e.g., frog-toad), orthographically (e.g., toad-told), and homophonically (e.g., toad-towed) related word pairs in Experiment 2. Taken together, these results indicate that following the initial activation of semantic representations, activation automatically feeds back to orthographic, but not phonological, representations during the early stages of word processing. These findings were discussed in the context of current accounts of visual word recognition.     

Lexical ambiguity, semantic context, and visual word recognition.

Some alternative hypotheses about the recognition of ambiguous words are considered. According to the selective-access hypothesis, prior semantic context biases people to access one meaning of an ambiguous word rather than another in lexical memory during recognition. In contrast, the nonselectiveaccess hypothesis states that all meanings of the word are accessed regardless of the context. We tested certain versions of these hypotheses by having students decide whether selected strings of letters were English words. The stimuli included test sequnces of three words in which the second word had two distinct possible meanings, whereas the first and third words were related to these meanings in various ways. When the first and third words were related to the same meaning of the ambiguous second word (e.g., SAVE-BANK-MONEY), the reaction time to recognize the third word decreased. But when the first and third words were related to different meanings of the second word (e.g., RIVER-BANK-MONEY), the reaction time for the third word was not reliably different from a control sequence with unrelated words. These and other data favor the selective-access hypothesis. Selective access to lexical memory is discussed in relation to models of word recognition.     

Semantic context effects in visual word recognition: An analysis of semantic strategies

Using a procedure that isolates the facilitatory and interfering effects of a semantic context, the present study examines two distinct patterns of context effects. One pattern shows a dominance of facilitation for target words in a related context, and the other pattern shows a dominance of interference for target words in an unrelated context. The controlling factor seems to be the overall characteristics of the stimulus list. For materials that include semantic relationships that are consistent in the strength of the relationships, facilitation dominance obtains. For materials that include a wide range of semantic relationship strengths, interference dominance results. These two patterns of facilitation and interference are attributed to two semantic strategies available to subjects for using context information. The explication of the strategies includes a theoretical treatment of the present data.     

Attention constraints of semantic activation during visual word recognition

The reduction of semantic priming following letter search of the prime suggests that semantic activation can be blocked if attention is allocated to the letter level during word processing. Is this true even for the very fast-acting component of semantic activation? To test this, the authors explored semantic priming of lexical decision at stimulus onset asynchronies (SOAs) of either 200 or 1,000 ms. Following semantic prime processing, priming occurred at both SOAs. In contrast, no priming occurred at the long SOA following letter-level processing. Of greatest interest, at the short SOA there was priming following the less demanding consonant/vowel task but not following the more attention-demanding letter search task. Hence, semantic activation can occur even when attention is directed to the letter level, provided there are sufficient resources to support this activation. The authors conclude that the default setting during word recognition is for fast-acting activation of the semantic system.     

Semantic context and word frequency effects in visual word recognition

Semantic context and word frequency factors exert a strong influence on the time that it takes subjects to recognize words. Some of the explanations that have been offered for the effects of the two factors suggest that context and frequency should interact, and other explanations imply additivity. In a recent study, Schuberth and Eimas reported that context and frequency effects added to determine their subjects' reaction times in a lexical decision (word vs. nonword) task. The present experiment reexamines this question with improved procedures. The data show that context and frequency do interact, with a semantic context facilitating the processing of low-frequency words more than high-frequency words.     

Modelling the effects of semantic ambiguity in word recognition

Most words in English are ambiguous between different interpretations; words can mean different things in different contexts. We investigate the implications of different types of semantic ambiguity for connectionist models of word recognition. We present a model in which there is competition to activate distributed semantic representations. The model performs well on the task of retrieving the different meanings of ambiguous words, and is able to simulate data reported by Rodd, Gaskell, and Marslen-Wilson [J. Mem. Lang. 46 (2002) 245] on how semantic ambiguity affects lexical decision performance. In particular, the network shows a disadvantage for words with multiple unrelated meanings (e.g., bark) that coexists with a benefit for words with multiple related word senses (e.g., twist). The ambiguity disadvantage arises because of interference between the different meanings, while the sense benefit arises because of differences in the structure of the attractor basins formed during learning. Words with few senses develop deep, narrow attractor basins, while words with many senses develop shallow, broad basins. We conclude that the mental representations of word meanings can be modelled as stable states within a high-dimensional semantic space, and that variations in the meanings of words shape the landscape of this space.     

Adult age differences in the effects of sentence context and stimulus degradation during visual word recognition

I investigated adult age differences in the efficiency of feature-extraction processes during visual word recognition. Participants were 24 young adults (M age = 21.0 years) and 24 older adults (M age = 66.5 years). On each trial, subjects made a word/nonword discrimination (i.e., lexical decision) regarding a target letter-string that was presented as the final item of a sentence context. The target was presented either intact or degraded visually (by the presence of asterisks between adjacent letters). Age differences in lexical decisions speed were greater for degraded targets than for intact targets, suggesting an age-related slowing in the extraction of feature-level information. For degraded word targets, however, the amount of performance benefit provided by the sentence context was greater for older adults than for young adults. It thus appears that an age-related deficiency at an early stage of word recognition is accompanied by an increased contribution from semantic context.     

Homophone interference effects in visual word recognition

In three lexical decision experiments and one progressive demasking experiment, performance on low-frequency heterographic homophones having a high-frequency mate was compared with performance on non-homophone target words with or without high-frequency orthographic neighbours. Robust homophone interference effects were observed in all experiments, as well as inhibitory effects of neighbourhood frequency. When speed-accuracy trade-offs were reduced, the homophone interference effects were found to be additive with effects of high-frequency orthographic neighbours. Furthermore, the size of homophone interference effects increased when pseudohomophone stimuli were presented among the nonwords. These results are tentatively interpreted within the framework of a bi-modal interactive activation model.     

Neighborhood frequency effects and letter visibility in visual word recognition.

Two experiments are described that measured lexical decision latencies and errors to five-letter French words with a single higher frequency orthographic neighbor and control words with no higher frequency neighbors. The higher frequency neighbor differed from the stimulus word by either the second letter (e.g., ASTRE-AUTRE) or the fourth letter (CHOPE-CHOSE). Neighborhood frequency effects were found to interact with this factor, and significant interference was observed only to CHOPE-type words. The effects of neighborhood frequency were also found to interact with the position of initial fixation in the stimulus word (either the second letter or the fourth letter). Interference was greatly reduced when the initial fixation was on the critical disambiguating letter (i.e., the letter P in CHOPE). Moreover, word recognition was improved when subjects initially fixated the second letter relative to when they initially fixated the fourth letter of a five-letter word, but this second-letter advantage practically disappeared when the stimulus differed from a more frequent word by its fourth letter. The results are interpreted in terms of the interaction between visual and lexical factors in visual work recognition.     

General slowing in semantic priming and word recognition.

Analyses of lexical decision studies revealed that (a) older (O) adults' mean semantic priming effect was 1.44 times that of younger (Y) adults, (b) regression lines describing the relations between older and younger adults' latencies in related (O = 1.54 Y-112 and unrelated conditions (O = 1.50 Y-93) were not significantly different, and (c) that there was a proportional relation between older and younger adults' priming effects (O = 1.48 Y-2). Analyses of word-naming studies yielded similar results. Analyses of delayed pronunciation data (Balota & Duchek, 1988) revealed that word recognition was 1.47 times slower in older adults, whereas older adults' output processes were only 1.26 times slower. Overall, analyses of whole latencies and durations of component processes provide converging evidence for a general slowing factor of approximately 1.5 for lexical information processing.     

Syllabic length effects in visual word recognition and naming

Two experiments investigated the role of the number of syllables in visual word recognition and naming. Experiment 1 (word and nonword naming) showed that effects of number of syllables on naming latencies were observed for nonwords and very low-frequency words but not for high-frequency words. In Experiment 2 (lexical decision), syllabic length effects were also obtained for very low-frequency words but not for high-frequency words and nonwords. These results suggest that visual word recognition and naming do require syllabic decomposition, at least for very low-frequency words in French. These data are compatible with the multiple-trace memory model for polysyllabic word reading [Psychol. Rev. 105 (1998) 678]. In this model, reading depends on the activity of two procedures: (1) a global procedure that operates in parallel across a letter string (and does not generate a strong syllabic length effect) and that is the predominant process in generating responses to high-frequency words, and (2) an analytic procedure that operates serially across a letter string (and generates a strong syllabic length effect) and that is the predominant process in generating responses to very low-frequency words. A modified version of the dual route cascaded model [Psychol. Rev. 108 (1) (2001) 204] can also explain the present results, provided that syllabic units are included in this model. However, the Parallel Distributed Processing model [Psychol. Rev. 96 (1989) 523; J. Exp. Psychol.: Human Perception Perform. 16 (1990) 92] has difficulties to account for these results.     

Dissociative effects of phonological vs. semantic associates on recognition memory in the Deese/Roediger-McDermott paradigm

Using a variation of the Deese/Roediger–McDermott paradigm in four experiments, we examined hit rate, false alarm rate, and memory discriminability (d′) for critical items (e.g., sleep) after their semantic associates (e.g., dream, rest, and awake), phonological associates (e.g., bleep, sheep, and cheap) or unrelated items were studied. Replicating previous research (e.g., Neely & Tse, 2007), d′ was lower for critical items than for yoked associates in semantic lists. However, d′ was higher for critical items than for yoked associates in phonological lists, even when the same critical items were used for these two list types. The memory discriminability of critical items was enhanced by phonological lists via a larger increase in their hit rates than in their false alarm rates, relative to the same critical items in lists of unrelated words. These findings (a) could not be fully accounted for by the activation-based theories proposed in the false memory literature, and (b) may suggest that the memory discriminabilities of semantic and phonological lists are modulated by two distinct activation mechanisms.     

Sequential effects of phonological priming in visual word recognition

Two masked priming experiments were conducted to examine phonological priming of bisyllabic words in French, and in particular, whether it operates sequentially or in parallel. Bisyllabic target words were primed by pseudowords that shared either the first or the second phonological syllable of the target. Overlap of the first syllable only-not the second-produced facilitation in both the lexical decision and the naming tasks. These findings suggest that, for polysyllabic words, phonological codes are computed sequentially during silent reading and reading aloud.     

Homophone effects in visual word recognition depend on homophone type and task demands.

This experiment examined how the characteristics of homophones and their mates influence homophone effects, as a function of task demands. Two types of homophones were presented: 1) low-frequency homophones with higher-frequency mates that are not animal names (e.g., maid--made), and 2) low-frequency homophones with mates that are, on average, of equivalent frequency and are animal names (e.g., foul--fowl). We observed a double dissociation: In the lexical decision task (LDT), there was a homophone effect for the first type of homophones but not for the second, whereas in the semantic categorization task (SCT) the opposite was true. These results suggest that in these tasks the effects of homophony arise when the homophone's mate creates competition in terms of the type of processing emphasized in the task, namely, orthographic processing in the LDT and semantic processing in the SCT.     

Neighborhood frequency effects and letter visibility in visual word recognition

Two experiments are described that measured lexical decision latencies and errors to five-letter French words with a single higher frequency orthographic neighbor and control words with no higher frequency neighbors. The higher frequency neighbor differed from the stimulus word by either the second letter (e.g.,astre-autre) or the fourth letter (chope-chose). Neighborhood frequency effects were found to interact with this factor, and significant interference was observed only tochope-type words. The effects of neighborhood frequency were also found to interact with the position of initial fixation in the stimulus word (either the second letter or the fourth letter). Interference was greatly reduced when the initial fixation was on the critical disambiguating letter (i.e., the letterp inchope). Moreover, word recognition was improved when subjects initially fixated the second letter relative to when they initially fixated the fourth letter of a five-letter word, but this second-letter advantage practically disappeared when the stimulus differed from a more frequent word by its fourth letter. The results are interpreted in terms of the interaction between visual and lexical factors in visual word recognition.     

Additive and interactive effects on response time distributions in visual word recognition

Across 3 different word recognition tasks, distributional analyses were used to examine the joint effects of stimulus quality and word frequency on underlying response time distributions. Consistent with the extant literature, stimulus quality and word frequency produced additive effects in lexical decision, not only in the means but also in the shape of the response time distributions, supporting an early normalization process that is separate from processes influenced by word frequency. In contrast, speeded pronunciation and semantic classification produced interactive influences of word frequency and stimulus quality, which is a fundamental prediction from interactive activation models of lexical processing. These findings suggest that stimulus normalization is specific to lexical decision and is driven by the task's emphasis on familiarity-based information.     

Interpretation of orthographic uniqueness point effects in visual word recognition

The orthographic uniqueness point (OUP) of a word is the position of the first letter from the left that distinguishes a word from all other words. In 2 recent studies (P. J. Kwantes & D. J. K. Mewhort, 1999a; A. K. Lindell, M. E. R. Nicholls, & A. E. Castles, 2003), it has been observed that words with an early OUP were processed more quickly than words with a late OUP. This has been taken to suggest that observers process the letters of words sequentially in a left-to-right order. In this article, it is shown that the OUP results do not provide selective evidence for left-to-right sequential processing in visual word recognition because the data are also compatible with an account in which letter processing occurs in random order.     

Electrophysiological evidence of different loci for case-mixing and word frequency effects in visual word recognition

Do word frequency and case mixing affect different processing stages in visual word recognition? Some studies of online reading have suggested that word frequency affects an earlier, perceptual-encoding stage and that case mixing affects a later, central decision stage (e.g., Reingold, Yang, & Rayner, Journal of Experimental Psychology: Human Perception and Performance 36:1677-1683 2010); others have suggested otherwise (e.g., Allen, Smith, Lien, Grabbe, & Murphy, Journal of Experimental Psychology: Human Perception and Performance 31:713-721 2005; Besner & McCann, 1987). To determine the locus of the word frequency and case-mixing effects, we manipulated word frequency (high vs. low) and case type (consistent lower case vs. mixing case) in a lexical-decision paradigm. We measured two event-related-potential components: the N170 (an early peak occurring 140-240 ms after stimulus onset, related to structural encoding) and the P3 (a late peak occurring 400-600 ms after stimulus onset, related to stimulus categorization). The critical finding was that the N170 amplitude was sensitive to case mixing, but the P3 amplitude was sensitive to word frequency and lexicality. These results suggest that case mixing affects an earlier processing stage than does word frequency, at least with respect to lexical-decision processes.