Effects of search criterion upon unanticipated free recall of categorically related words

Ss determined whether words in a list were members of a relatively general or specific category (e.g., foods vs vegetables), and then they were given an unanticipated free recall test. Assumptions were that: (1) evaluating a word against a general criterion (e.g., food) results in the detection of fewer semantic elements than would evaluating it against a specific criterion (e.g., vegetable), and (2) detecting more semantic elements primes memory. In three studies, free recall scores were highest for the specific search. Instructions to form an image or to think of an association for each word did not improve recall. Telling Ss, just before recall, what categories composed the list increased recall clustering, but not recall.     

Does<Emphasis Type="SmallCaps">LGHT</Emphasis> prime<Emphasis Type="SmallCaps">DARK</Emphasis>? Masked associative priming with addition neighbors

We present two masked priming lexical decision experiments in which we examined whether a nonword prime word would activate associative/semantic information from its corresponding addition neighbor (e.g.,lght-DARK via the addition neighborlight), producing associative/semantic priming. The rationale was the following: If a nonword prime with a missing letter produced a semantic/associative priming effect, this would clearly indicate that this nonword was activating the lexical/semantic representations of its base word, thereby reinforcing the models of visual-word recognition in which the orthographic representations produced bylght (orligt) andlight are quite similar (e.g., SOLAR, SERIOL, open-bigram, and overlap models). The results showed that the magnitude of the masked associative priming effect with subset primes was remarkably similar to that of the priming effect with the corresponding word prime. Furthermore, the magnitude of the associative priming effect was similar when the deleted letter was a vowel and when the deleted letter was a consonant.     

The Semantic Simon Effect

Three experiments are reported in which a semantic variant of the Simon paradigm was used. In Experiment 1, participants saw Dutch and English words that corresponded to names of animals (e.g. DOG) or occupations (e.g. TEACHER). Participants were instructed to respond by saying ANIMAL or OCCUPATION, depending on whether the presented word was a Dutch or English word (i.e. relevant stimulus feature) but irrespective of whether the word was the name of an animal or an occupation (i.e. irrelevant stimulus feature). Results showed that responses were facilitated when the correct response corresponded to the name of the semantic category of the presented word (e.g. saying 'ANIMAL' to DOG) compared to when it was the name of a different semantic category (e.g. saying 'OCCUPATION' to DOG), even though the semantic category of the presented word was irrelevant and had to be ignored. Category membership also influenced response times when letter case (upper- or lower-case: Experiment 2) and grammatical category (noun or adjective: Experiment 3) had to be determined in order to select a category label as a response. The semantic Simon effect offers a new tool that can be used to study automatic semantic processing.     

Differential impacts of age of acquisition on letter and semantic fluency in Alzheimer's disease patients and healthy older adults

The degree to which the typical age of acquisition (AoA) of words and word frequency have separable influences on verbal production tasks has been strongly debated. To examine the overlap between these factors in verbal fluency tasks, the performance of Alzheimer's disease (AD) patients (N = 34) and normal elderly controls (N = 36) was compared on semantic (e.g., vegetables) and letter (e.g., words that begin with F) fluency tasks. These comparisons revealed that words generated for the semantic fluency task had an earlier AoA while words generated for the letter fluency task had a higher word frequency. Differences in AoA between AD patients and controls were larger for semantic than letter fluency. These results suggest that AoA has an effect on verbal production that is independent of word frequency and that AoA has a semantic locus.     

Pervasive influence of semantics in letter and category fluency: a multidimensional approach

We used multidimensional statistical procedures to study semantic and lexical processes underlying word retrieval in verbal-fluency performance. Forty healthy participants were given a two-choice letter task (i.e., generate items beginning with the letter 'A' or 'F', in any order) and a two-choice category task (i.e., generate animal or fruit names, in any order). Using correspondence analysis (CoA) and hierarchical clustering (HC), we found evidence of prominent semantic organization in both letter and category fluency. For example, a striking categorical segregation between animate and inanimate entities emerged during the letter task. Analysis of inter-item times revealed strong sequential priming effects in both tasks. Taken together, these results indicate that semantic facilitation is pervasive in word retrieval processes, even in the letter-fluency task, and therefore suggest that the traditional view of letter fluency as a purely phonemically based task should be revised. Finally, our findings may help explain patterns of verbal-fluency measures obtained in focal brain lesion patients.     

Detection and identification of words and letters in simulated visual search of word lists

Ss were shown a rapid sequence of words and had to (a) make a speeded response to the presentation of a predefined target and (b) report a "response word" which they thought immediately followed the target in the sequence. In Experiment I presentation rate was varied orthogonally with the number of alternative targets. Detection errors and latency increased with target set size, as did the distance of the response word from the target in the list sequence. Increases in presentation rate produced greater target-response distance without affecting detection time. In Experiment II Ss were in some conditions given only the initial letter of the targets; the response could be either the whole word following the target or only its initial letter. The results indicated that Ss could, within limits, concurrently detect initial letters and identify words. Alternatives to hierarchical-type models of stimulus processing in visual search were discussed.     

On the categorical nature of the semantic interference effect in the picture-word interference paradigm

Two picture-word interference experiments are reported in which the boundaries of the semantic interference effect are explored. In both experiments, participants named pictures (e.g., a picture of a car) that appeared with superimposed word distractors. Distractor words from the same semantic category as the word for the picture (e.g., CAR) produced semantic interference, whereas semantically related distractors from a different category (e.g.,Bumper) led to semantic facilitation. In Experiment 2, the semantic facilitation from semantically related distractors was replicated. These results indicate that a semantic relationship between picture and distractor does not necessarily lead to interference and in fact can lead to facilitation. In all but one case tested until now, a semantic relationship between picture and distractor has led to semantic facilitation. The implications of these results for the assumption that the semantic interference effect arises as a consequence of lexical competition are discussed.     

Differential impacts of age of acquisition on letter and semantic fluency in Alzheimer's disease patients and healthy older adults

The degree to which the typical age of acquisition (AoA) of words and word frequency have separable influences on verbal production tasks has been strongly debated. To examine the overlap between these factors in verbal fluency tasks, the performance of Alzheimer's disease (AD) patients (N?=?34) and normal elderly controls (N?=?36) was compared on semantic (e.g., vegetables) and letter (e.g., words that begin with F) fluency tasks. These comparisons revealed that words generated for the semantic fluency task had an earlier AoA while words generated for the letter fluency task had a higher word frequency. Differences in AoA between AD patients and controls were larger for semantic than letter fluency. These results suggest that AoA has an effect on verbal production that is independent of word frequency and that AoA has a semantic locus.     

The overlap model: a model of letter position coding

Recent research has shown that letter identity and letter position are not integral perceptual dimensions (e.g., jugde primes judge in word-recognition experiments). Most comprehensive computational models of visual word recognition (e.g., the interactive activation model, J. L. McClelland & D. E. Rumelhart, 1981, and its successors) assume that the position of each letter within a word is perfectly encoded. Thus, these models are unable to explain the presence of effects of letter transposition (trial-trail), letter migration (beard-bread), repeated letters (moose-mouse), or subset/superset effects (faulty-faculty). The authors extend R. Ratcliff's (1981) theory of order relations for encoding of letter positions and show that the model can successfully deal with these effects. The basic assumption is that letters in the visual stimulus have distributions over positions so that the representation of one letter will extend into adjacent letter positions. To test the model, the authors conducted a series of forced-choice perceptual identification experiments. The overlap model produced very good fits to the empirical data, and even a simplified 2-parameter model was capable of producing fits for 104 observed data points with a correlation coefficient of .91.     

Semantic facilitation with pictures and words

The present experiments explored the role of processing level and strategic factors in cross-form (word-picture and picture-word) and within-form (picture-picture and word-word) semantic facilitation. Previous studies have produced mixed results. The findings presented in this article indicate that semantic facilitation depends on the task and on the subjects' strategies. When the task required semantic processing of both picture and word targets (e.g., category verification), equivalent facilitation was obtained across all modality combinations. When the task required name processing (e.g., name verification, naming), facilitation was obtained for the picture targets. In contrast, with word targets, facilitation was obtained only when the situation emphasized semantic processing. The results are consistent with models that propose a common semantic representation for both picture and words but that also include assumptions regarding differential order of access to semantic and phonemic features for these stimulus modalities.     

Processing visual words with numbers: Electrophysiological evidence for semantic activation

Perea, Duñabeitia, and Carreiras (Journal of Experimental Psychology: Human Perception and Performance 34:237–241, 2008) found that LEET stimuli, formed by a mixture of digits and letters (e.g., T4BL3 instead of TABLE), produced priming effects similar to those for regular words. This finding led them to conclude that LEET stimuli automatically activate lexical information. In the present study, we examined whether semantic activation occurs for LEET stimuli by using an electrophysiological measure called the N400 effect. The N400 effect, also known as the mismatch negativity, reflects detection of a mismatch between a word and the current semantic context. This N400 effect could occur only if the LEET stimulus had been identified and processed semantically. Participants determined whether a stimulus (word or LEET) was related to a given category (e.g., APPLE or 4PPL3 belongs to the category “fruit,” but TABLE or T4BL3 does not). We found that LEET stimuli produced an N400 effect similar in magnitude to that for regular uppercase words, suggesting that LEET stimuli can access meaning in a manner similar to words presented in consistent uppercase letters.     

Test of the phonological recoding hypothesis using a letter-delay task

In some English words is a silent letter in the letter strings, e.g., PSALM. This type of word provides room to manipulate phonological similarity against the words with a nonsilent letter in the corresponding position, e.g., PASTA, to test the phonological recoding hypothesis. Letter strings excluding the silent letter or the sounding letter, e.g., _salm and a phonological condition, _asta as an orthographic condition, were presented. A "psalm-type word" was processed faster than pasta-type word," indicating that phonology plays a leading role in word recognition.     

Phonological Activation in Multi-syllabic Sord Recognition

Three experiments were conducted to test the phonological recoding hypothesis in visual word recognition. Most studies on this issue have been conducted using mono-syllabic words, eventually constructing various models of phonological processing. Yet in many languages including English, the majority of words are multi-syllabic words. English includes words incorporating a silent letter in their letter strings (e.g., champane). Such words provide an opportunity for investigating the role of phonological information in multi-syllabic words by comparing them to words that do not have the silent letter in the corresponding position (e.g., passener). The performance focus is on the effects of removing letters from words with a silent letter and from words with a non-silent letter. Three representative lexical tasks—naming, semantic categorization, lexical decision—were conducted in the present study. Stimuli that excluded a silent letter (e.g., champa_ne) were processed faster than those that excluded a sounding letter (e.g., passen_er) in the naming (Experiment 1), the semantic categorization (Experiment 2), and the lexical decision task (Experiment 3). The convergent evidence from these three experiments provides seminal proof of phonological recoding in multi-syllabic word recognition. An erratum to this article can be found at     

Beginning readers activate semantics from sub-word orthography

Two experiments assessed whether 7-year-old children activate semantic information from sub-word orthography. Children made category decisions to visually-presented words, some of which contained an embedded word (e.g., hip in ship). In Experiment 1 children were slower and less accurate to classify words if they contained an embedded word related in meaning to the category (e.g., slower to reject ship as a ‘body part’ than an ‘animal’), especially when the embedded word was higher in frequency than the carrier word. This demonstrates that young children activate semantic information from sub-word orthographic representations, and that they do so from the relatively early stages of learning to read. Experiment 2 replicated this effect. Furthermore, we observed semantic interference regardless of whether the embedded word shared its pronunciation with the carrier (e.g., the hip in ship) or not (e.g., the crow in crown), and regardless of its position within the carrier, suggesting that interference was not dependent on phonological mediation. These findings show that by 7-years-of age, children have begun to establish an orthographic system that is capable of activating sub-word orthographic patterns, strong enough to connect with meaning, when reading words silently.     

Semantic access in second-language visual word processing: Evidence from the semantic Simon paradigm

The present study investigated whether visually presented second-language words activate their meaning during low-level word processing, just as native-language words do. Using the semantic Simon paradigm (De Houwer, 1998) with a letter-case judgment task, Dutch-English bilingual participants were instructed to classify targets’ letter case using verbal labels (e.g., by saying “animal” to uppercase targets or “occupation” to lowercase targets). Results showed that both native-language and second-language targets yielded faster responses if the verbal response corresponded to the targets’ semantic category (e.g., the response “animal” to the target LEEUW or LION) than when it did not (e.g., LAWYER), even though the meaning of target words was irrelevant for the task. These results show that second-language word forms may quickly and automatically activate their meaning through strong form-to-meaning mappings, which is consistent with theories of bilingual lexicosemantic organization, such as that of Duyck and Brysbaert (2004).     

Cognitive aspects of lexical availability

Lexical availability measures the ease with which a word can be generated as a member of a given category. It has been developed by linguistic studies aimed, among other things, at devising a rational basis for selecting words for inclusion in dictionaries. The measure accounts for the number of people who generated a given word as a member of a designated semantic category and the position in which they produce the word. We present an analysis of lexical availability from a cognitive perspective. Data were analysed for Spanish speakers generating words from five semantic categories—clothes, furniture, body parts, animals, and intelligence. Six properties of words were investigated as potential predictors of lexical availability. Predictors were concept familiarity, typicality, imageability, age of acquisition, word frequency, and word length. Categories differed on these variables, and regression analysis found concept familiarity, typicality, and age of acquisition to be significant predictors of lexical availability. The cognitive basis of these findings and the practical consequences of selecting words on the basis of lexical availability are considered.     

Familiarity and organization of category terms in semantic memory

In order to determine production frequencies for various category terms, 219 college students were asked to generate category terms (e.g. Automobiles, Vegetables, Relatives) during a 4-rain period. The production frequency (i.e., the number of subjects who listed a particular term) for a given category term may be considered as reflecting the familiarity or amount of usage of that category term, and, as such, should be of value to memory researchers in designing experiments. Additionally, examination of the order in which terms were produced showed that subjects "clustered" related category terms, (e.g., "Countries" and "States" were often produced successively). This clustering of category terrms is supportive of the hypothesis that categories are organized in semantic memory in some kind of higher order structure.     

On the role of refixations in letter strings: the influence of oculomotor factors

Recent studies of reading and word recognition have shown that eye-movement behavior depends strongly on the position in the word that the eye first fixates; the probability of refixating in a word is lowest with the eye near the middle of the word, and it increases as the eye fixates to either side. It has generally been assumed that the cause for this optimal landing position phenomenon lies in the very strong drop-off of visual acuity even within the fovea; refixation should be more likely when the eye starts from a noncentral position, because here less information can be extracted during one fixation. It may, however, be the case that the phenomenon is caused not by acuity drop-off, but by differences in within-word oculomotor scanning tactics as a function of the position that the eye initially fixates. To test this, in the present experiment we kept visual information constant while we varied the initial fixation position. We used homogeneous strings of letters of different length. One letter in each string was different from the rest (e.g., kkkkkok), and this was the letter that the subject initially fixated. This target letter had to be identified before saccading to a comparison string. The position of the target letter in the string was varied from trial to trial. If, owing to acuity limitations, refixations reflect insufficient information extraction, then, because the target letter is always directly fixated, the pattern of refixations in this condition should be independent of the first fixation position. However, the obtained refixation probability showed a strong dependence on the position of first fixation. The number of refixations was independent of the absolute length of the letter strings, but it seemed to be influenced by the proportion of the string over which the eye had to pass. The larger this proportion, the higher the probability of refixation. The results suggest that to a certain extent refixations in letter strings (or words) reflect properties of the oculomotor system rather than visual information extraction.     

Congruency effects in the letter search task: Semantic activation in the absence of priming

Semantic priming is typically eliminated when participants perform a letter search on the prime, suggesting that semantic activation is conditional upon one's attentional goals. However, in such studies, semantic activation (or the lack thereof) is not measured during the letter search task itself but, instead, is inferred on the basis of the responses given to a later target. In the present study, direct online evidence for semanticactivation was tested using words whose meaning should bias either a positive or a negative response (e.g.,present vs. absent). In Experiment 1, a semantic congruency effect was obtained, with faster responses when the word meaning matched the required response. Experiment 2 replicated the congruency effect while, simultaneously, showing the elimination of semantic priming. It is concluded that letter search does not affect the initiation of semantic activation. Possible accounts for the elimination of priming following letter search include activation-based suppression and transfer-inappropriate processing.     

Category size effects in semantic and letter fluency in Alzheimer's patients

Many studies have found that patients with Alzheimer's disease (AD) perform significantly worse than normal controls on verbal fluency tasks. Moreover, some studies have found that AD patients' deficits compared to controls are more severe for semantic fluency (e.g., vegetables) than for letter fluency (e.g. words that begin with F). These studies, however, have not taken category size into account. A comparison of AD patients and age-matched controls on three semantic and three letter categories revealed that both the size and type of a category significantly predicted AD patients' deficits on verbal fluency tasks. These results suggest that the verbal fluency of AD patients will be most attenuated on large semantic categories.