On the role of word frequency in the detection of component letters

The experiments reported in this study were conducted to explore the issue of race models versus holistic models of word processing. In both types of model, it is assumed that an available word-level encoding for a display will conceal letter information, and thereby inhibit component-letter detection. However, whereas in holistic models it is assumed that encoding always should occur at the word or pattern level first, in the race models it is assumed that encoding occurs at all levels (e.g., feature, letter, and word) simultaneously, with the final level of encoding being at whatever level has been completed first. If the rate of word-level encoding is facilitated by increasing word frequency, the holistic models predict a generally declining latency for letter detection, because the initial step in letter detection (i.e., word-level encoding) will be occurring more rapidly. The race models, on the other hand, predict that with increasing word frequency there will be an increasing chance that the word-level encoding will win the encoding race, resulting in an increase in the latency for letter detection (i.e., the word code will conceal the letter codes). Two experiments are reported, and the obtained pattern of latency data appears to be most consistent with the race models.     

Semantic effects in visual word detection with visual similarity controlled

In three experiments, subjects searched through word lists for a single target word. Search was faster when the target word belonged to a different semantic category from that of the background words with visual similarity controlled. This semantic effect increased with number of items to be searched through, and it obtained whether the target was cued visually or verbally. Semantic homogeneity within the background also speeded search, but only when subjects had no prior knowledge of the nature of a list. Several models of the semantic effect are described. All contrast the encoding of physical identity with the encoding of semantic attributes, but they differ in ascribing the effect to: (1) the relative access times for these codes, (2) the power of the codes in dealing with multiple comparisons, or (3) the attentional demands of comparison using different levels of code.     

Altering memory through recall: The effects of cue-guided retrieval processing

Three experiments were designed to investigate the influence of initial recall on memory by assessing delayed recall after different immediate cued-recall tests. In all experiments, subjects performed semantic and phonemic encoding tasks on a word list. The subjects then received a cued-recall test that cued the target using the same word as the context word in the encoding task, a test that cued the target with a word from the same level at which the target was encoded, a test that cued the target with a cue from a different level at which the target was encoded, or no immediate-recall test. One day later, the subjects performed a final cued-recall test in which the type of cue (semantic or phonemic) was varied. Consistently, delayed recall was facilitated primarily when the cue on the immediate test was from the same level as the cue on the delayed test. This pattern of facilitation suggests that immediate cued-recall produces an elaboration of an existing memory representation that is closely tied to the type of cue used on the immediate test.     

Sentence frame contexts and lexical decisions: Sentence-acceptability and word-relatedness effects

Many studies have explored the effects of single-word contexts on visual word recognition, and several models have been proposed to account for the results obtained. However, relatively little is known about the effects of sentence contexts. In the experiment reported, the contexts consisted of sentences with the final word deleted, and subjects made word-nonword (lexical) decisions on target strings of letters. Norms were collected to determine the most common completion for each sentence frame. The experiment yielded three main findings: (1) Lexical decisions were fastest for words that were the most common completions; (2) among words not given as completions in the norming procedure, decisions were faster for words related to the most common completions than for words unrelated to the most common completions; t3t also among words that were not produced as completions, decisions were faster for words that formed acceptable completions than for words that did not. These relatedness and sentence-acceptability effects were independent, so that the relatedness effect held even when the target words formed anomalous sentence completions. In order to account for these results, a model combining two types of processes is required. In the model described, schematic knowledge (Rumelhart & Ortony, 1977) operates upon a semantic network to activate particular nodes, and this activation spreads to related concepts as in the Collins and Loftus (1975) model.     

The effect of orthographic structure on word recognition in a visual search task

The effect of the orthographic structure of the stimulus field on the visual search performance of third graders (8-8 years), sixth graders (11-7 years) and adults was investigated in three experiments. In Experiment 1, where the predesignated target was one word, subjects of all ages searched equally fast through fields consisting of words, pseudowords, and nonwords. In contrast, subjects of all ages displayed effects of orthographic structure when searching for instances of a semantic category (Experiment 2) or for three words (Experiment 3). Subjects searched faster through nonwords than through pseudowords and faster through pseudowords than through words. The use of orthographic structure to facilitate search did not increase with age, suggesting that children of the youngest age group were already making maximal use of intraword redundancy.     

Episodic effects on the visual comparison of letters in words.

In two experiments, subjects compared the identity of either the first letters of displays or all the letters in displays. Words yielded faster decisions than did pseudowords (pronounceable items derived by changing a vowel in a word) only when entire displays were compared. In a training phase run before the comparison task, subjects had written down either the first letters or entire displays. Relative to items that had not appeared in the training phase, prior experience at writing entire displays facilitated same decisions about entire displays and interfered with different decisions about entire displays. Prior experiences did not moderate the processing of first-letter identities. It was concluded that episodic effects arise from the interaction of higher order information underlying lexical encoding. Prelexical processing of letters is not sensitive to episodic effects.     

Spatial Orienting Controlled without Awareness: A Semantically Based Implicit Learning Effect

Three experiments tested whether spatial attention can be influenced by a predictive relation between incidental information and the location of target events. Subjects performed a simple dot detection task; 600 msec prior to each target a word was presented briefly 5 to the left or right of fixation. There was a predictive relationship between the semantic category (living or non-living) of the words and target location. However, subjects were instructed to ignore the words, and a post-experiment questionnaire confirmed that they remained unaware of the word-target relationship. In all three experiments, given some practice on the task, response times were faster when targets appeared at likely ( p = 0.8), compared to unlikely ( p = 0.2) locations, in relation to lateral word category. Experiments 2 and 3 confirmed that this effect was driven by semantic encoding of the irrelevant words, and not by repetition of individual stimuli. Theoretical implications of this finding are discussed.     

Effects of sentence constraint on priming in natural language comprehension

In 4 cross-modal naming experiments, researchers investigated the role of sentence constraint in natural language comprehension. On the sentence constraint account, incoming linguistic material activates semantic features that in turn pre-activate likely upcoming words. The 1st and 2nd experiments investigated whether stimulus offset asynchrony played a critical role in previous studies supporting the sentence constraint account. The 3rd and 4th experiments examined further predictions of the sentence constraint account, in particular whether pre-activated words would compete for activation. In Experiment 3, the researchers manipulated whether an expected target word had a close competitor and found that response to the expected word was facilitated regardless of the proximity of a competitor. The 4th experiment established that close competitors were primed by the sentence frames and should have been available to compete with expected target words. Thus, word-level representations did not compete for activation.     

Episodic effects on the visual comparison of letters in words

In two experiments, subjects compared the identity of either the first letters of displays or all the letters in displays. Words yielded faster decisions than did pseudowords (pronounceable items derived by changing a vowel in a word) only when entire displays were compared. In a training phase run before the comparison task, subjects had written down either the first letters or entire displays. Relative to items that had not appeared in the training phase, prior experience at writing entire displays facilitatedsame decisions about entire displays and interfered withdifferent decisions about entire displays. Prior experiences did not moderate the processing of first-letter identities. It was concluded that episodic effects arise from the interaction of higher order information underlying lexical encoding. Prelexical processing of letters is not sensitive to episodic effects.     

Units of word recognition: Evidence for the use of multiple units

The present experiments were concerned with subsyllabic units in word recognition. The studies employed a same-different RT task. A one-syllable word and a probe were presented simultaneously, and subjects responded “same” if the probe was an integral subset of the word (BLAST:BL), and “different” otherwise (BLAST:BC). Probes included single letters (BLAST:L), doublets (BLAST:LA), triplets (BLAST:LAS), and the whole word (BLAST: BLAST). The first experiment suggested that a variety of spelling patterns, as well as the whole word, served as units of processing. In particular, initial consonant clusters were processed as quickly as single letters, and only slightly faster than the whole words. Consonant strings were used in the second experiment, which demonstrated spelling pattern effects with permissible strings (BLGST:BL) as compared to nonpermissable strings (BXJPK:BX). A third experiment demonstrated that the particular effective units depend on task demands.     

Lateralization of lexical codes in auditory word recognition

Three experiments examined the lateralization of lexical codes in auditory word recognition. In Experiment 1 a word rhyming with a binaurally presented cue word was detected faster when the cue and target were spelled similarly than when they were spelled differently. This orthography effect was larger when the target was presented to the right ear than when it was presented to the left ear. Experiment 2 replicated the interaction between ear of presentation and orthography effect when the cue and target were spoken in different voices. In Experiment 3, subjects made lexical decisions to pairs of stimuli presented to the left or the right ear. Lexical decision times and the amount of facilitation which obtained when the target stimuli were semantically related words did not differ as a function of ear of presentation. The results suggest that the semantic, phonological, and orthographic codes for a word are represented in each hemisphere; however, orthographic and phonological representations are integrated only in the left hemisphere.     

Scanning,holistic encoding,and the word-superiority effect

The role of holistic encoding induced by scanning in the superior identifiability target letters in orthographic strings (words) enjoy over those in strings of unrelated letters was examined in two experiments. Both the set of potential targets and the critical position in the letter arrays were predesignated. One group in each experiment was induced to scan each array from left to right in a dot-counting task. A dot could precede the array to its left and/or appear with the array to its right. Only this group displayed the word superiority. For the second group in the first experiment, any dot(s) present always appeared with the array. The second group in the second experiment was shown no dots but, rather, performed the letter-identification task only. The absence of a word-superiority effect in other studies is related to holistic encoding stemruing from scanning requirements, and the implications for positional uncertainty explanations of the phenomenon are discussed.     

On time differences in searching for letters in words and nonwords: Do they emerge during the initial encoding or the subsequent scan?

Krueger (1970a, 1970b, 1982) has demonstrated that subjects can search for target letters within words faster than they can complete an equivalent search through nonwords, and he further demonstrated that the effect did not arise during the comparison stage. The present study involved three experiments in which the usual word advantage disappeared either when subjects knew where within a display the target item would appear (i.e., it was always the first letter), or when all the component letters were encoded into memory before the task began (i.e., a memory-search task). These data, in conjunction with Krueger's, where interpreted as localizing at least one (and possibly the only) source of the word-nonword difference in this task to the events that occur during the item-to-item transitions subjects make when scanning the letter arrays. That is, these transitions are faster for words than nonwords, and it was suggested that the time difference may emerge because although all the letters from within a word appear to be available in memory before the scan begins, this seems not to be true for consonant arrays. Given that this is the case, part of the word-nonword difference may be attributable to subsequent encoding events that would be needed for the consonant arrays as the scan moves from letter to letter.     

Stress priming in picture naming: an SOA study

This study investigates whether or not the representation of lexical stress information can be primed during speech production. In four experiments, we attempted to prime the stress position of bisyllabic target nouns (picture names) having initial and final stress with auditory prime words having either the same or different stress as the target (e.g., WORtel-MOtor vs. koSTUUM-MOtor; capital letters indicate stressed syllables in prime-target pairs). Furthermore, half of the prime words were semantically related, the other half unrelated. Overall, picture names were not produced faster when the prime word had the same stress as the target than when the prime had different stress, i.e., there was no stress-priming effect in any experiment. This result would not be expected if stress were stored in the lexicon. However, targets with initial stress were responded to faster than final-stress targets. The reason for this effect was neither the quality of the pictures nor frequency of occurrence or voice-key characteristics. We hypothesize here that this stress effect is a genuine encoding effect, i.e., words with stress on the second syllable take longer to be encoded because their stress pattern is irregular with respect to the lexical distribution of bisyllabic stress patterns, even though it can be regular with respect to metrical stress rules in Dutch. The results of the experiments are discussed in the framework of models of phonological encoding.     

The more,the better?: Number of decisions as a determinant of memorability

Three experiments tested alternative explanations to the Johnson-Laird, Gibbs, and deMowbray (1978) proposal that the number of decisions made about a word is a major determinant of its memorability. The alternatives considered were increased processing time, retrieval aids, and the number of positive decisions. In Experiment 1, subjects made a speeded classification about each word for a category defined by three properties. Though items with more target properties were processed longer and better remembered, within a property level processing time was not associated with better memory. In Experiment 2, subjects received three properties, but different groups responded “Yes” to words with all three properties, words with any of the three properties, or whether words had each of the properties. As predicted by the number-of-decisions hypothesis, but not by the other hypotheses, with an increasing number of target properties, recall generally increased in the ALL group, decreased in the ANY group, and remained constant in the EACH group. In Experiment 3, this recall pattern was replicated with a different set of two target properties. The number-of-decisions notion is contrasted to the elaboration principle, and a simple model is proposed. It is concluded that the number of decisions is a useful technique for investigating within-level encoding differences     

Unconscious processing of dichoptically masked words

In three experiments, the subjects' task was to decide whether each of a series of words connoted something good (e.g., fame, comedy, rescue) or bad (stress, detest, malaria). One-half second before the presentation of each such target word, an evaluatively polarized priming word was presented briefly to the nondominant eye and was masked dichoptically by either the rapidly following (Experiment 1) or simultaneous (Experiments 2 and 3) presentation of a random letter-fragment pattern to the dominant eye. (The effectiveness of the masking procedure was demonstrated by the subjects' inability to discriminate the left vs. right position of a test series of words.) In all experiments, significant masked priming effects were obtained; evaluative decisions to congruent masked prime-target combinations (such as a positive masked prime followed by a positive target) were significantly faster than those to incongruent (e.g., negative prime/positive target) or noncongruent (e.g., neutral prime/positive target) combinations. Also, in two of the three experiments, when subjects were at chance accuracy in discriminating word position, their position judgments were nevertheless significantly influenced by the irrelevant semantic content (LEFT vs. RIGHT) of the masked position-varying words. The series of experiments demonstrated that two very different tasks--speeded judgment of evaluative meaning and nonspeeded judgment of word position--yielded statistically significant and replicable influences of the semantic content of apparently undetectable words. Coupled with previous research by others using the lexical decision task, these findings converge in establishing the reliability of the empirical phenomenon of semantic processing of words that are rendered undetectable by dichoptic pattern masking.     

More than meets the eye: Context effects in word identification

The influence of semantic context on word identification was examined using masked target displays. Related prime words enhanced a signal detection measure of sensitivity in making lexical decisions and in determining whether a probe word matched the target word. When line drawings were used as primes, a similar benefit was obtained with the probe task. Although these results suggest that contextual information affects perceptual encoding, this conclusion is questioned on the grounds that sensitivity in these tasks may be determined by independent contributions of perceptual and contextual information. The plausibility of this view is supported by a simulation of the experiments using a connectionist model in which perceptual and semantic information make independent contributions to word identification. The model also predicts results with two other analytic methods that have been used to argue for priming effects on perceptual encoding.     

Metaphors and the mental lexicon.

In two experiments we investigate the possibility that lexicalization can account for the distinction between literal and metaphorical language. In both experiments, sentence contexts were presented with the final word missing. When subjects signaled they understood the context, two possible final words were presented and subjects were required to decide which was more appropriate. Semantic decision times over five different types of stimuli investigating literal and metaphorical word usage were consistent with a modified class inclusion model in which both the lexicalized meaning of words and the context in which they are presented make essential contributions to understanding.     

The role of visual attention in saccadic eye movements

The relationship between saccadic eye movements and covert orienting of visual spatial attention was investigated in two experiments. In the first experiment, subjects were required to make a saccade to a specified location while also detecting a visual target presented just prior to the eye movement. Detection accuracy was highest when the location of the target coincided with the location of the saccade, suggesting that subjects use spatial attention in the programming and/or execution of saccadic eye movements. In the second experiment, subjects were explicitly directed to attend to a particular location and to make a saccade to the same location or to a different one. Superior target detection occurred at the saccade location regardless of attention instructions. This finding shows that subjects cannot move their eyes to one location and attend to a different one. The results of these experiments suggest that visuospatial attention is an important mechanism in generating voluntary saccadic eye movements.     

Meaning,amount of processing,and memory for words

Two experiments were carried out in order to try to resolve the controversy about whether the semantic processing of a word necessarily involves all the elements of its meaning. In the first experiment, subjects categorized a list of auditorially presented words according to whether or not they were natural consumable solids (e.g., “apple“). They were then given an unexpected test of their ability to recall the whole list, which contained equal numbers of words with none, one, two, or all three of the target components. The results confirmed the prediction that the greater the number of components a word has in common with a target category, the better it will be recalled. The second experiment used a visual presentation of a list of words, which subjects scanned for members of a particular target category. There were four different target categories assigned to independent groups of subjects. The results again confirmed the prediction. On the assumption that memorability in such tasks is determined by amount of processing, we conclude that some elements of the meaning of a word can be processed without having to process all of them.