A model for evidence accumulation in the lexical decision task

We present a new model for lexical decision, REM-LD, that is based on REM theory (e.g., ). REM-LD uses a principled (i.e., Bayes' rule) decision process that simultaneously considers the diagnosticity of the evidence for the 'WORD' response and the 'NONWORD' response. The model calculates the odds ratio that the presented stimulus is a word or a nonword by averaging likelihood ratios for lexical entries from a small neighborhood of similar words. We report two experiments that used a signal-to-respond paradigm to obtain information about the time course of lexical processing. Experiment 1 verified the prediction of the model that the frequency of the word stimuli affects performance for nonword stimuli. Experiment 2 was done to study the effects of nonword lexicality, word frequency, and repetition priming and to demonstrate how REM-LD can account for the observed results. We discuss how REM-LD could be extended to account for effects of phonology such as the pseudohomophone effect, and how REM-LD can predict response times in the traditional 'respond-when-ready' paradigm.     

The frequency effect for pseudowords in the lexical decision task

Four experiments were designed to investigate whether the frequency of words used to create pseudowords plays an important role in lexical decision. Computational models of the lexical decision task (e.g., the dual route cascaded model and the multiple read-out model) predict that latencies to low-frequency pseudowords should be faster than latencies to high-frequency pseudowords. Consistent with this prediction, results showed that when the pseudowords were created by replacing one internal letter of the base word (Experiments 1 and 3), high-frequency pseudowords yielded slower latencies than low-frequency pseudowords. However, this effect occurred only in the leading edge of the response time (RT) distributions. When the pseudowords were created by transposing two adjacent internal letters (Experiment 2), high-frequency pseudowords produced slower latencies in the leading edge and in the bulk of the RT distributions. These results suggest that transposed-letter pseudowords may be more similar to their base words than replacement-letter pseudowords. Finally, when participants performed a go/no-go lexical decision task with one-letter different pseudowords (Experiment 4), high-frequency pseudowords yielded substantially faster latencies than low-frequency pseudowords, which suggests that the lexical entries of high-frequency words can be verified earlier than the lexical entries of low-frequency words. The implications of these results for models of word recognition and lexical decision are discussed.     

Priming effects on lexical access and decision processes: A signal-detection analysis

Summary Signal-detection methodology was employed to examine the assumption that in a lexical-decision task context effects are primarily the result of post-access processes. Experiment 1, in which prime-relatedness was varied within subjects, found changes in target sensitivity (d) without corresponding changes in the response criterion. This outcome was interpreted as evidence that prior context facilitates lexical access, whereas post-access contributions remain constant across conditions. When prime-relatedness was varied between subjects in Experiment 2, the lexical-decision task showed differing context effects on access processes as well as on post-access processes. It was concluded that subjects adopt a single response criterion suited to maximize task performance. The particular response criterion adopted is a function of the stimulus set rather than a function of the relationship between prime and target on any single trial. Finally, it was concluded that post-access strategies alone are insufficient to account for context effects obtained when typical lexical-decision-task procedures are used, or to account for the magnitude of the differences obtained between the present experiments.     

The effect of preview eccentricity in a lexical decision task

We report lexical decision experiments in which eye movements and lexical decision time were analysed. The results show that nonwords produced more fixation than words, and that the time to make a lexical decision was also greater for nonwords. Further, a preview of the stimulus was presented on some occasions either at fixation or peripherally. When the presentation was peripheral the number of refixations and lexical decision times were reduced. Parafoveal previews of words also reduced word length effects on refixations and lexical decision time. These effects decreased (for nonwords) when the case of the letters was changed in the preview. These results are compatible with the idea that the peripheral preview benefit derives from word visual structure in addition to information about word length, word envelope, and single letter identities.     

Long-term priming of neighbours biases the word recognition process: evidence from a lexical decision task.

The role of orthographically similar words (i.e., neighbours) in the word recognition process has been studied extensively using short-term priming paradigms (e.g., Colombo, 1986). Here we demonstrate that long-term effects of neighbour priming can also be obtained. Experiment 1 showed that prior study of a neighbour (e.g., TANGO) increased later lexical decision performance for similar words (e.g., MANGO), but decreased performance for similar pseudowords (e.g., LANGO). Experiment 2 replicated this bias effect and showed that the increase in lexical decision performance due to neighbour priming is selectively due to words from a relatively sparse neighbourhood. Explanations of the bias effect in terms of lexical activation and episodic memory retrieval are discussed.     

Visual word recognition and vowelization in Arabic: new evidence from lexical decision task performances

The effect of vowelization signs on the process of visual word recognition in Arabic was investigated among 41 native Arab skilled readers with age average of 30.66 ± 9.09. The participants performed a lexical decision task using three types of words and pseudowords; full, partial and non-vowelized. The results showed that for both words and pseudowords, response times were shorter and accuracy levels were higher for the non-vowelized condition compared to the other conditions of vowelization. The results reinforce the argument that automatic lexical processes during word recognition in Arabic orthography might be disturbed by supplementary information such as vowelization.     

Retroactive semantic priming in a lexical decision task

The present study reports two experiments that required subjects to name target items preceded by a masked prime. Additionally, and subsequent to the naming task, subjects were required to indicate whether or not the prime was a word, along with a confidence rating of their lexical decision. Experiment 1 demonstrates that the processing of masked primes is facilitated by related targets when such targets are presented either 100 or 200 msec after the onset of the prime. Experiment 2 extends the finding of “retroactive” priming to a 1000=msec separation in prime-target presentation (SOA). The extent of retroactive priming is not dependent on SOA between prime and target, nor is it affected by the prime-mask SOA, which varied from 10 to 180 msec. Priming of targets was also independent of prime-target and prime-mask SOA, providing that primes had been classified as words. For word primes classified as non-words there was no semantic priming on target naming reaction time. Implications of these findings with respect to the nature of retroactive priming and the current controversy concerning subliminal priming effects were discussed.     

Sequential dependencies in the lexical decision task

Two experiments addressed whether response latency in a trial of the lexical decision task is independent of the lexical status of the item presented in the previous trial. In Exp. 1, it was found that both word and nonword responses were significantly slower when the previous trial had involved a nonword than when it had involved a word. In Exp. 2, which employed a different list composition, it was found that responses to nonwords and pseudohomophones were significantly slower when the previous trial had involved a nonword or a pseudohomophone than when it had involved a word. However, responses to words were not influenced by the nature of the previous trial. We concluded that sequential dependencies exist across consecutive trials in the lexical decision task even when there is no semantic, morphological, phonological, or orthographic relationship between the items presented during those trials.     

Phonological encoding in the lexical decision task

In lexical decision experiments, subjects have difficulty in responding NO to non-words which are pronounced exactly like English words (e.g. BRANE). This does not necessarily imply that access to a lexical entry ever occurs via a phonological recoding of a visually-presented word. The phonological recoding procedure might be so slow that when the letter string presented is a word, access to its lexical entry via a visual representation is always achieved before phonological recoding is completed. If prelexical phonological recodings are produced by using grapheme-phoneme correspondence rules, such recodings can only occur for words which conform to these rules (regular words), since applications of the rules to words which do not conform to the rules (exception words) produce incorrect phonological representations. In two experiments, it was found that time to achieve lexical access (as measured by YES latency in a lexical decision task) was equivalent for regular words and exception words. It was concluded that access to lexical entries in lexical decision experiments of this sort does not proceed by sometimes or always phonologically recoding visually-presented words.     

Semantic priming effects from single words in a lexical decision task

The present research examines the semantic priming effects of a centrally presented single prime word to which participants were instructed to either "attend and remember" or "ignore". The prime word was followed by a central probe target on which the participants made a lexical decision task. The main variables manipulated across experiments were prime duration (50 or 100 ms), the presence or absence of a mask following the prime, and the presence (or absence) and type of distractor stimulus (random set of consonants or pseudowords) on the probe display. There was a consistent interaction between the instructions and the semantic priming effects. Relative to the "attend and remember" instruction, an "ignore" instruction produced reduced positive priming from single primes presented for 100 ms, irrespective of the presence or absence of a prime mask, and regardless of whether the probe target was presented with or without distractors. Additionally, reliable negative priming was found from ignored primes presented for briefer durations (50 ms) and immediately followed by a mask. Methodological and theoretical implications of the present findings for the extant negative priming literature are discussed.     

Emotion words and categories: evidence from lexical decision

We examined the categorical nature of emotion word recognition. Positive, negative, and neutral words were presented in lexical decision tasks. Word frequency was additionally manipulated. In Experiment 1, “positive” and “negative” categories of words were implicitly indicated by the blocked design employed. A significant emotion–frequency interaction was obtained, replicating past research. While positive words consistently elicited faster responses than neutral words, only low frequency negative words demonstrated a similar advantage. In Experiments 2a and 2b, explicit categories (“positive,” “negative,” and “household” items) were specified to participants. Positive words again elicited faster responses than did neutral words. Responses to negative words, however, were no different than those to neutral words, regardless of their frequency. The overall pattern of effects indicates that positive words are always facilitated, frequency plays a greater role in the recognition of negative words, and a “negative” category represents a somewhat disparate set of emotions. These results support the notion that emotion word processing may be moderated by distinct systems.     

The mispriming effect: Evidence of an orthographic check in the lexical decision task

This paper describes a lexical decision experiment that demonstrates that there are increased rates of errors for words “misprimed” with words strongly associated with visually similar words (e.g., BREAD-BATTER) relative to rates for the same words preceded by completely unrelated words (e.g., SLEEP-BATTER). The pattern of results is shown to be inconsistent with Forster’s (1976) search model but consistent with a criterion-bias model supplemented by an orthographic checking process.

     

Repetition and practice effects in a lexical decision task

Ss classified visually presented verbal units into the categories “in your vocabulary” or “not in your vocabulary.” The primary concern of the experiment was to determine if making a prior decision on a given item affects the latency of a subsequent lexical decision for the same item. Words of both high and low frequency showed a systematic reduction in the latency of a lexical decision as a consequence of prior decisions (priming) but did not show any reduction due to nonspecific practice effects. Nonwords showed no priming effect but did show shorter latencies due to nonspecific practice. The results also indicated that many (at least 36) words can be in the primed state simultaneously and that the effect persists for at least 10 min. The general interpretation was that priming produces an alteration in the representation of a word in memory and can facilitate the terminal portion of the memory search process which is assumed to be random.     

Associative strength effects in the lexical decision task

Four experiments explore the role of automatic and attentional processing in producing strength effects in a lexical decision task. Experiment I manipulated the relative proportion of related and unrelated pairs, the stimulus-onset-asynchrony (SOA), and the strength of the prime-target relationship. Results indicated that strength was independent of the proportion of related and unrelated pairs and SOA. Experiment 2 manipulated the relative proportion of strong and weak related pairs and the strength of the prime-target relationship at a relatively long SOA interval (500 msec). Results showed that the strength effect was present when more strong than weak pairs were presented, and it was absent when the stimulus list contained more weak than strong pairs. Experiment 3 replicated the more weak pairs condition of Experiment 2 but with a short SOA interval (100 msec) and showed that the strength effect was found regardless of the large number of weak related pairs presented. Experiment 4 manipulated strength of the prime-target relationship and proportion of strong and weak pairs but introducing a neutral prime condition and a longer SOA interval (1000 msec). Results are discussed within a two-process model (Posner & Snyder, 1975) postulating that the strength effect at short SOAs is due to automatic processes, whereas at long SOAs it is due to the influence of attentional processes.     

Strategic associative priming in the lexical decision task

Two experiments explore the nature of prelexical expectancy processes in the lexical decision task. The strength of the prime-target relationship and the size of the associative set defined by the prime were manipulated in both experiments. In Experiment 1, the proportion of strong relative to weak primes induced subjects to include strong and weak candidate words in their expectancy set, whereas in Experiment 2 that proportion attempted to induce subjects to include mainly strongly related words. Results showed that priming depended on whether the primes were included in the set. Thus, in Experiment 1 facilitation was obtained for both strong and weak primes, whereas in Experiment 2 the facilitation of weak primes depended on the size of the associative set defined by the prime. Results are discussed within a theoretical framework that includes prelexical expectancy processes in the lexical decision task.     

Semantic processing in aphasia: Evidence from an auditory lexical decision task

W. Milberg and S. E. Blumstein (1981, Brain and Language 14, 371–385) demonstrated semantic facilitation effects in a visual lexical decision task administered to Wernicke and other aphasics with severe comprehension deficits. In an attempt to explore the generalizability of these findings in a task where the acoustic-phonetic system could not be bypassed to access meaning, Wernicke's, Global, Broca's, and Conduction aphasics were administered a lexical decision task in the auditory modality. The patients were also given a simple semantic judgment task using the word pairs from the lexical decision task. The aphasic patients showed evidence of semantic facilitation whether they were categorized by diagnostic group or comprehension level. Performance of the semantic judgment task correlated with the severity of auditory comprehension deficits, whereas the consistency of the semantic facilitation effect did not. Even patients with severe comprehension deficits showed semantic facilitation. These results decrease the likelihood that auditory comprehension deficits are due to semantic organization per se and increase the likelihood that the deficits lie in one of the many processes involved in access to that information.     

Length effect in reading and lexical decision: evidence from skilled readers and a developmental dyslexic participant

A number of experimental data have shown that naming latency increases with length for pseudo-words but not for frequent real words. Different interpretations have been proposed by current models of reading to account for such a length effect. The aim of the present study was to assess the impact of lexicality on length effect in both the reading and lexical decision tasks. For this purpose, skilled readers were asked to either name or make a lexical decision on words and pseudo-words differing in length from one to three syllables. Skilled readers' results show that length effect is modulated by lexicality in the reading task but no length effect was found in the lexical decision task. The tasks were further proposed to a well-compensated dyslexic participant who exhibited a visual attentional disorder in the absence of any associated phonological problems. A length effect on RTs was found for both words and pseudo-words in lexical decision but naming latencies were affected by length for the pseudo-words only. The present results largely conform to the predictions of the ACV98 model of reading. They are not compatible with the PDP models of reading and can only be partially accounted for by dual route models.     

On the nature of neutral primes in a lexical decision task

Summary Research concerned with semantic priming has used a neutral prime as a benchmark for measuring the amount of facilitation for related targets and the amount of inhibition for unrelated targets. Recently, de Groot, Thomassen, and Hudson (1982) have reported that lexical decisions to targets are faster when preceded by the neutral prime BLANK as compared to a neutral prime consisting of a string of X's. Additionally, Antos (1979) has reported that an X neutral prime induces an inhibitory effect when the stimulus-onset-asynchrony (SOA) is short. The present experiment manipulated class of neutral prime, SOA, and practice. The results failed to support the observation by Antos. However, the results did support the finding by de Groot et al. at shorter SOA's (200 and 550 ms). At a longer (1000 ms) SOA the effect of the two neutral primes as well as the effect of the unrelated primes were equivalent. Practice had no differential effect on either of the neutral primes as compared to the unrelated priming conditions. These results were interpreted to mean that the difference between the two neutral primes at a brief SOA were perceptual in origin and that an unrelated word prime is neutral with respect to the target in the absence of strategic priming effects.