Automatic and attentional processes in the effects of sentence contexts on word recognition

JOURNAL OF VERBAL LEARNING AND VERBAL BEHAVIOR 18, 1 20

(1979)

Automatic and Attentional Processes in the Effects of Sentence Contexts on Word Recognition IRA FISCHLERAND PAUL A. BLOOM

University of Florida An incomplete sentence context facilitated a subsequent lexical decision only when the test word was a highly likely completion of the sentence. Context had no effect on congruent but unlikely words, whileit inhibited responses to anomalouswords. The inhibition was eliminated in a control condition in which none of the test words meaningfully completed the context. In contrast, subjects could not eliminate the inhibition or the facilitation when they were instructed to ignore the implication of each context. It was concludedthat contextualinformation in reading is typicallyused to focusattention on a class of responseswhichconservethe meaningfulnessofthe sentence, but that the deployment of attention will vary with the predictability of the material. A .fundamental component of skilled reading is the ability to quickly and accurately recognize a word given an appropriate visual stimulus. Even for inexperienced readers, word recognition appears to be influenced by the structure and meaning of the material being read (e.g., Goodman, 1969). Any complete model of the reading process must, therefore, be able to specify when and how the contextual information present in a sentence affects the recognition of words. The present paper is addressed to three aspects of this problem: First, how specific is the effect of context on word retrieval? As a sentence is being read, what is the size and nature of the set of words potentially influenced by the context? Second, given this set of words, is the

The research reported in this paper was supported by a National Institute of Mental Health Grant, No. RO3 MH30395, to the first author. We thank Daniel Tumarkin, Eric Nietzke, Robert Murray, and Lisa Rosenfeld for their assistance in data collection. James Neely, Richard Schuberth, and the anonymous reviewer are to be thanked for valuable comments on an earlier version of the paper. Portions of the first three experiments were reported at the meeting of the American Psychological Association, San Francisco, August, 1977. Reprint requests should be addressed to Ira Fischler, Department of Psychology, University of Florida, Gainesville, Florida 32611.

effect of context predominantly one of facilitation or inhibition? And third, to what extent can a skilled reader control the specificity and nature of these contextual effects? In other words, how automatic is the influence of sentence contexts on word retrieval? Both syntactic and semantic constraints have been shown to affect the identification of words under a variety of conditions. Miller and Isard (1963), for example, found that with auditory presentation, a sequence of words was more accurately reported if they formed a syntactically correct sentence. Similar results have been obtained with- rapid visual presentation of the words of a sentence (Forster, 1970). The effect of disrupting normal syntax on performance should not be surprising, since such violations rarely occur in normal text, and errors in oral reading rarely violate syntactic rules (Weber, 1970). More importantly, knowing that the next word of a sentence must be a noun places few constraints on the identity of the word, particularly since many lexical items can serve multiple syntactic roles. Conserving syntactic structure, then, still leaves a considerable set of words which may or may not be affected by context. Tulving and Gold (1963) found that the visual duration threshold for a word was 0022-5371/79/'010001-20502.00/0 Copyright © 1979 by Academic Press, Inc.

2

F1SCHLER AND BLOOM

reduced if the word was preceded by a semantically congruent sentence context. Words which were syntactically appropriate but incongruent with the context (e.g., "Three people were killed in a highway RASPBERRY") showed increased thresholds compared to those for words with no prior context. The facilitation appeared to be a function of the probability that the context would elicit the particular test word, since several items which were semantically acceptable (e.g., COLLISION in the above sentence) showed no effect of context, compared to the no-context control. Morton (1964) also found less reduction in visual threshold for appropriate but unlikely response words. Although these results have typically been addressed to the questions of how contextual and visual information are combined (e.g., Tulving, Mandler, & Baumal, 1964; Morton, 1969; Marslen-Wilson & Welsh, 1978), they also suggest that a sentence context produces two distinct effects on word recognition: There is, on the one hand, a facilitation of a rather small set of words likely to follow a given context, and on the other hand, an inhibition of a much larger set of words which do not conserve the overall meaning of the sentence. A theoretical framework for dealing with the facilitation and inhibition of signals has recently been developed, primarily by Posner and Snyder (1975a,b) and by Schneider and Shiffrin (e.g., 1977), which distinguishes automatic and attentional aspects of information processing. Automatic processes Occur rapidly, facilitate certain responses without inhibiting other responses, and are unaffected by. a subject's strategies and expectancies. These qualities follow from the independence of such processes from ,a limited-capacity attentional system. Automatic processes are also unavoidable, in the sense that a subject cannot choose n o t to make an automatic response, given an appropriate stimulus. Attentional processes, in contrast, are effortful and slow to implement, actively inhibit other responses requiring attention, and are under

the subject's active control. This framework has been applied with success to a wide range of tasks, including visual search (Schneider & Shiffrin, 1977), letter-matching (Posner & Snyder, 1975b) and the development of word recognition skills (LaBerge & Samuels, 1974). The distinction between automatic and attentional processes has proven useful in describing the effects of a single-word semantic context on lexical decision latency. In the lexical decision task, a subject must decide ,whether or not a given string of letters is a word. Meyer and Schvaneveldt (1971) showed that when subjects had to decide that two items were both words, latency was shorter if the second was a primary associate of the first, than if the two words were unrelated. While Schvaneveldt and Meyer (1973) argued for an automatic "spread of excitation" model of the effect, Posner and Snyder (1975a) suggested that both automatic and attentional factors could be operating and that they could be separated by manipulating the expectations of the subject, by varying the time available between the priming stimulus and the test item, and by adding a control condition which compares latency for both related and unrelated pairs to a "no-prime" control condition. In the last technique, attentional factors are indicated by a significant inhibition of latency for unrelated pairs compared to the control condition. If this occurs, any facilitation observed for related pairs may have both attentional and automatic components. Evidence for both types of processes was reported by Neely (1976, 1977). Neely (1976) presented subjects with a priming stimulus that was either a word or a neutral signal, followed by a stimulus that required a lexical decision. On positive trials, latency to the test stimulus was shorter if it was an associate of the prime, compared to the neutral signal condition. Latency was actually slower for words with unrelated primes than with neutral primes, indicating the inhibitory effect described by Posner and Snyder (1975a). Neely

EFFECTS OF CONTEXT ON WORD RECOGNITION

has also shown that if the time between the prime and the test stimulus is reduced to 250msec, the inhibitory effect disappears, whereas a significant facilitation remains. This facilitation for semantically related words (e.g., BODY-head) is still obtained at the 250msec interval when subjects are told to expect a test item from a different semantic category than the prime and when the proportion of test items actually related to the prime is low (e.g., the prime word BODY in such a "shift" condition would be followed by exemplars of birds on 80~o of the positive trials, and exemplars of body parts on 20~o of these trials). By Posner and Snyder's (1975a) logic, these results also demonstrate an automatic component to association. Fischler (1977a) found a significant facilitation for semantically related pairs under conditions which precluded active expectancies about the associates. Conversely, with a prime-test delay of about 600msec, Tweedy, Lapinski, and Schvaneveldt (1977) found a significant effect of the probability of a relatedpair trial on the size of the facilitation, as would be expected from an attentional priming process. These results indicate that both automatic and attentional processes may contribute to the effect of a semantic context in the lexical decision task. The presence of both inhibition and facilitation in the earlier visual threshold studies suggests that a similar analysis is possible for semantic contexts which take the form of sentences, rather than single words. Recently, Schuberth and Eimas (1977) found that sentence contexts produced facilitation of the lexical decision for words congruent with the context, and inhibition of the decision for incongruent words. These results d~monstrated the feasibility of using the lexical decision priming paradigm for analyzing the effects of sentence contexts on word retrieval. The present research may be considered an elaboration of the Schuberth and Eimas (1977) study, although our theoretical framework is quite different from the modified Logogen model (Morton, 1.969)

3

which Schuberth and Eimas make use of in discussing their results. Details of their experiments will be considered below. Taylor's (1953) Cloze technique for assessing the predictability of sentence contexts was used in the present experiments to establish the scope of the facilitation and inhibition effects observed by Tulving and Gold (1963) and by Schuberth and Eimas (1977). The set of sentence contexts used covered the entire range of response dominance. That is, some contexts elicited a particular response with high frequency, while others elicited a wide variety of responses, with no single highly dominant response. Presentation of the dominant, or primary, response as a test item produces a function relating latency to the predictability of a given test word. If, upon reading a sentence context, a subject expects a particular word to occur, then a facilitation for highly dominant words should be obtained, but this facilitation should decrease rapidly with decreases in predictability, and there should be inhibition for low-dominant responses, even though they are the wimary ones for that context. On the other hand, the lack of inhibition for unlikely responses observed by Tulving and Gold (1963) suggests that the facilitation is automatic, with activation proportional to the word's likelihood given the sentence context. This could be the case even if the comprehension of the context itself required attention and effort (see, for example, Kintsch & Keenan, 1973; Dooling, 1972). While the generation of expectancies may require effort, once a word or set of words has been activated by this process, these words could then remain more available at no cost to other test words. A second function is obtained by presenting unlikely but acceptable test words. It may be that the effects of context on the availability of these words depends on whether a dominant response to the sentence exists. If, for example, a subject forms expectancies only for highdominant contexts, then unlikely test words might be inhibited if they follow such contexts,

4

FISCHLER

but not if they follow contexts of low dominance. A third function is obtained by presenting words which are syntactically acceptable but semantically anomalous in a given context. Prior results suggest there will be an overall inhibition of such words. Again, the amount of inhibition may vary with the dominance of the Cloze response. For example, if both the facilitation and inhibition observed by Schuberth and Eimas are created by a single process, such as the generation of expectancies for dominant contexts only, more inhibition should be obtained with such contexts. For negative trials, pronounceable nonwords were generated which were highly similar to the corresponding sets of test words. For example, following the context, "He mailed the letter without a," a subject might be shown "STIMP." Such a "dominant nonword" should tend to elicit a positive response, and produce either more false alarms than contexts with less dominant responses, and/or longer latencies for correct negative responses. In Experiment 1 of the present study, the degree of facilitation and inhibition was determined for the three major classes of test words by comparing latency in each condition to a control condition in which no context was presented prior to the lexical decision. In Experiments 2 and 3, a condition which controlled for the reading and comprehension of a sentence context was developed and was used to analyze the effects of response dominance. It also served as the control condition in the subsequent experiments. The attentional component of the context effects was further examined by increasing the time available for reading the sentence context (Experiment 4) and by changing the instructional set given to the subjects (Experiment 5). EXPERIMENT 1

Method Subjects. Sixty-four psychology students participated in Experiment 1. Subjects were

AND

BLOOM

"

assigned to one of two groups, context or noprime control, on the basis of when they signed up for the experiment. Three subjects in the context condition were deleted from further analysis because their subsequent verbal reports indicated that they did not attempt to read the sentences. One subject in the no-prime condition was deleted because of excessive errors (> 15~o). This left 30 subjects in each condition. Materials. A large set of incomplete sentences was given to an introductory psychology class of 100 students, who were told to complete each with a single appropriate word. From this set, 96 sentences were chosen over which the probability of the primary response (Dominance) ranges from .99 to .09, with an average probability of .53. These responses served as the primary test words. For each sentence context, a semantically appropriate but unlikely test word (mean probability of .03) was also selected. Finally, a test word which was syntactically, although not semantically, appropriate was selected for each context. The length, number of syllables, and frequency (Ku6era & Francis, 1967) of the words were matched across the three word types. Associations between individual context words and the test words were avoided. A pronounceable nonword was generated for each of the resulting 288 words by changing a single letter per syllable; thus each context was associated with six test items: three words (primary, unlikely, and anomalous) and three highly similar nonwords. A typical Context-test set is shown in Fig. 1. Apparatus. Stimuli were presented on a Super Bee videoterminal controlled by a PDP-8 computer. Response latencies were recorded on-line for later analysis. The letters were displayed white-on-black in a 5 x 7 dotmatrix. Writing time was approximately 1msec/letter. Procedure. Subjects in the Context condition were told that each trial in the experiment would involve reading a sentence context and making a lexical decision. The

EFFECTS OF CONTEXT ON WORD RECOGNITION

Experimental Condition Context (Expts. 1,4,5): No Prime (Expt. 1): Anomalous Control (Expt. 2):

Type of Lexical Decision Test: Primary (.99 > p > .09): Unlikely (mean p = .03): Anomalous (p = .00):

5

Example of Priming Stimulus She cleaned the dirt from her xxx xxxxxxx xxx xxx xxxxx xxx He poured himself a glass of

Word

Nonword

SHOES HANDS TERMS

CHOES MANDS FERMS

FIG. 1. Typicai sentence contexts and corresponding lexical decision test items used in the experiments.

nature of the lexical decision was explained. It was pointed out that when the test item was a word it would usually make sense given the sentence context, much as it would during normal reading. All but three subjects (who were replaced) indicated after the experiment that they had read the sentence contexts and had noticed the relationship between the context and test word. The importance of reading the sentence context was stressed, and subjects were told to respond as quickly and accurately as possible. In the no-prime condition, subjects saw a string of x's prior to the lexical decision stimulus. Subjects in this condition were told to merely observe the x's and then make a lexical, decision about the test item. Each sentence context (or string of x's~ was displayed on the video-terminal in lower case letters for 2 sec and then was deleted. One-half sec later, the lexical decision stimulus was presented in capital letters, subtending a horizontal visual angle of 1.24-3.70 °. The test item was left-justified, where the sentence or string of x's had begun. The test stimulus remained until a response was made. Two keys at opposite ends of the terminal keyboard were used for responding. Half of the subjects in each condition were told to respond with the forefinger of the left hand if the test item was a word and with the forefinger of the right hand if it was a nonword. The remainder of the subjects in each condition received opposite response instructions. Each subject in the context condition was shown each of the 96 sentence contexts

followed by one of the six test types; each item was tested equally often across subjects with each set of six subjects forming a replication. The order of the contexts was completely randomized. The first three trials of the session were composed of context-test sets other than those described above, and served to familiarize the subjects with the task.

Results The mean latency for correct responses within each of the six test conditions was calculated for each subject, and served as a single score in the analyses. Mean latencies across subjects are shown in the first two columns of Table 1. Considering the data for word trials first, it can be seen that the context had a substantial effect on lexical decision latency. Response times for unlikely word trials were 49msec longer than those for primary-word trials, while times for anomalous word trials were nearly 90 msec longer than those for unlikely words. Comparison to the no-prime control latencies indicates a small facilitation (21 msec) for primary words. The latencies for nonword trials, in contrast, show little effect of either context or of probability: The largest difference among the six means is only 22 msec. the error rates, shown in Table 2, yield a similar pattern: More errors occurred on nonword trials, and only the anomalous word items showed a substantial increase in errors over the no-prime control condition. An analysis of variance was performed with Response (word or nonword), Test Type

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FISCHLER AND BLOOM TABLE 1

MEAN LATENCY(IN MSEC)FOR SIX TYPESOF LEXICALDECISIONTEST ITEMSOVERFIVE EXPERIMENTALCONDITIONS Experimental condition

Type of test

2-sec context (Expt. 1)

No-prime control (Expt. 1)

Anomalous control (Expt. 2)

3-sec context (Expt. 4)

Suppression of context (Expt. 5)

Primary words Unlikely words Anomalous words

630 (18)" 679 (17) 768 (22)

651 (18) 649 (15) 655 (14)

640 (11) 665 (14) 662 (14)

644 (19) 697 (21) 770 (26)

636 (21) 678 (25) 739 (26)

Primary nonwords Unlikely nonwords Anomalous nonwords

794 (23) 798 (24) 798 (28)

793 (23) 820 (23) 803 (21)

779 (17) 811 (19) 792 (24)

838 (28) 847 (33) 813 (31)

800 (25) 804 (25) 801 (29)

aStandard error of means by subject. TABLE 2 PERCENTAGEOF ERRORFOR SIX TYPESOF LEXICALDECISIONTEST ITEMSOVERFIVE EXPERIMENTALCONDITIONS Experimental condition

Type of test

2-sec context (Expt. 1)

Primary Words Unlikely words Anomalous words

2.5 3.1 9.4

Primary nonwords Unlikely nonwords Anomalous nonwords

7.5 5.0 8.1

~

No-prime control (Expt. 1)

Anomalous control (Expt. 2)

3-sec context (Expt. 4)

Suppression of context (Expt. 5)

1.9 5.0 3.8

3.8 3.1 1.9

2.7 2.9 8.5

0.8 3.1 6.7

7.5 6.3 8.8

8.1 6.3 7.5

8.9 6.8 8.1

6.8 7.5 7.1

(primary, unlikely, or anomalous) and Group p<.05. This is seen in the overall slower (context or no-prime) as factors. The analysis latencies for words, but not for nonwords, in treated subjects as the only r~.ndom effect, the context condition. The Test Type by since each subject received a different subset of Response interaction was also significant, items in each condition, the main effect of F(2,116) = 15.45, p < .001. Group was not significant, F(1,58)< 1. There The interaction of Group, Test Type, and was a highly significant main effect of Response was significant, F(2,116)=15.14, Response with words producing faster re- p<.001. Subsequent pair-wise comparisons sponses, than nonwords, F(1,58)=142.70~ using Tukey's hsd procedure1 (see Winer 1971, p<.001. There was also a significant main p. 198) showed the primary-word trials to be effect of Test Type, F(2,116) -- 25.41, p < .001. 1In these and all other pair-wise comparisons reported The interaction of Group and Test Type was here, the between-groups MSe was derived by pooling the significant, F(2,116) = 19.23, p < .001; this is M S for subjects with all the interactions of subjects by seen in the increase in latency across test type other factors. The M S e for comparisons within subjects for the context, but not for the no-prime and across Test Type was derived by pooling the M S for condition. The Group by Response inter- the Subject x Test Type and Subject x Test Type x action reached significance, F(1,58),-- 5.12, Response interactions.

EFFECTS OF CONTEXT ON WORD RECOGNITION

somewhat faster than the unlikely-word trials, q(2,232) = 5.88, p < .01, and the unlikely word trials substantially faster than anomalous word trials, q(2,232) = 10.67, p < .01. However, between-group comparisons showed that neither the primary word nor unlikely word trials differed significantly from the corresponding control trials, q(2,348)= 1.01 and 1.05, respectively. The anomalous word trials, on the other hand, were significantly slower for the context than for the no-prime control condition, q(2,348) = 5.42, p < .01. Within the context condition, the relationship between the context and test had a clear effect on performance: Words which were primary responses to the context were responded to more quickly than were congruent but unlikely responses, which in turn produced substantially faster times than did semantically anomalous words. The betweengroups assessment of facilitation and inhibition, however, revealed only a substantial inhibition for anomalous words, and no effect of context for either primary or unlikely words, compared to the control condition. The absence of a significant facilitation for primary words by the presentation of a sentence context is inconsistent with earlier findings. Although between-group comparisons showed that the primary word latency with a context was not significantly different from that for the control, it seemed reasonable that the response might be facilitated for the most predictable words: Recall that the primary response words actually range in probability from .09 to .99, with an average of .53. A more basic question about the appropriateness of the no-prime conditionas baseline for assessing facilitation and inhibition had to be dealt with, however, before the effect of dominance could be determined. The relatively small amount of facilitation and substantial inhibition inferred here depends on the assumption that the act of reading and comprehending a sentence per se does not interfere with the subsequent lexical decision. If, however, the reading process for the context group

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tends to retard overall response time, then the means for this group would be slower by some constant amount, and therefore, the amount of facilitation would be underestimated, and inhibition overestimated. One version of this argument is that a sentence context constitutes a memory load which may interfere with subsequent responding. This load would presumably be of greater importance with complex primes such as sentences, than with single-word contexts. Schuberth and Eimas (1977), who first addressed this issue, required subjects to recall the sentence context following the lexical decision, insuring that the context be maintained in memory during the response. Nonetheless, overall latencies for their context and isolatedword conditions were not significantly different (630msec vs 644msec). In a further attempt to control for memory load, a condition was included in which subjects saw the names of four digits prior to the lexical decision. This procedure slowed responses significantly (62msec) compared to the isolated-word condition. The implication is that reading and maintaining a sentence have little effect on latency. The possibility remains, however, that the memory requirement reduced the overall context effect in the Schuberth and Eimas (1977) study; that is, having to remember and report the surface structure of a sentence may interfere with its comprehension. It seemed worthwhile, then, in view of the absence of facilitation in Experiment 1, to determine if the requirement of reading a sentence per se prior to the lexical decision might slow responding generally. EXPERIMENT 2 Clearly, the choice of a control group for assessing contextual effects is not trivial. An attempt was made in the next experiment to more closely approximate the linguistic task faced by subjects in the context condition in reading and comprehending a sentence. This was done by presenting to a new group of subjects the same sentence contexts and test

8

FISCHLER AND BLOOM

items as the context group of Experiment 1, but re-pairing the sentences and tests such that no test word was semantically appropriate in its context. If the inhibition of responses is under a subject's attentional control (Posner & Snyder, 1975a), the anomalous-control latencies should differ from the no-prime condition only to the extent that sentence comprehension per se interferes with the lexical decision, and subsequently can serve as a more appropriate baseline for assessing the relative degree of facilitation and inhibition.

Method Subjects. Thirty-two psychology students participated in Experiment 2. Two subjects were deleted from further analysis due to excessive errors. Thus 30 subjects were left in the anomalous control condition. Materials. The same sentence contexts and test items used in the context condition of Experiment 1 were employed. However, the sentences and test items were re-paired, so that each test word was anomalous given the sentence context. An example is given in Fig. 1. Apparatus. The same apparatus used in the first experiment was used in Experiment 2. Procedure. The procedure for the anomalous control subjects was the same as that for the context subjects in Experiment 1, except that these subjects were told that when the test item was a word, it would not make sense given the sentence context. However, subjects were still asked to read and comprehend the sentence context, and all reported they did so. Results The mean latency for correct responses within the six test types was calculated as before. Mean latencies across subjects are shown in Table 1, along with the data from Experiment 1. The results may be summarized briefly: There is no consistent or substantial difference between the latencies of the two control conditions. The largest difference between any two sets of items is 16msec. (It should be kept in mind that the primary and

unlikely words are now functionally "anomalous" for the subject. A three-way analysis of variance was performed, comparing the anomalous condition with the no-prime condition of Experiment 1. As expected, latency was shorter for words than for nonwords in both conditions, F(1,58) = 195.24, p < .001. The only other effect which reached significance was the main effect of Test Type, F(2,116)=6.22, p<.01. The crucial point is that there was not a slgnificant difference between the two groups, F(1,58) < 1.00. None of the interactions was significant. A second three-way analysis of variance was performed comparing the latencies of the context group from Experiment 1 and anomalous control group. Again, latency to words was faster than to nonwords, F(1,58)= 109.33, p < .001. The main effect of Test Type was also significant, F(2,116)=26.06, p<.001, and there was no overall difference between the two groups, F(1,58)< 1.00. Although there was no main effect of group, the interaction of Group and Test Type was significant, F(2,116)=12.87, p<.001. The Group by response interaction, unlike that of Experiment 1, was not significant, F(1,58)=2.10, p>.10. This was apparently due to the somewhat faster responses for words in the anomalous control. The Response by Test Type interaction was again significant, F(2,116) = 19.23, p < .001. The interaction of particular interest, Group by Test Type by Response, was significant, F(2,116)=13.68, p<.001. Betweengroup comparisons showed that neither primary-word nor unlikely-word trials differed significantly from the corresponding control items. Only the anomalous word trials were significantly different, showing inhibition in the context condition relative to the anomalous control condition, q(2,348)= 5.31, p < .01. These results closely follow the pattern obtained in Experiment 1. The error rates presented in Table 2 showed a pattern similar to. that obtained in Experi-

EFFECTS OF CONTEXT ON WORD RECOGNITION

ment 1 in that more errors occurred on nonword trials, and only the anomalous-word trials showed substantially more errors in the context than in the control condition. No significant differences were found in error rate between the no-prime and anomalous control groups. EXPERIMENT 3 Since the context and test word never formed a normal sentence in this condition, it was possible that subjects simply did not read the sentences, producing their own "noprime" condition, despite the instructions. To examine this possibility, an additional 12 context and 12 anomalous-control subjects were tested, and an incidental recognition test of the contexts was given following the session. The test consisted of 100 contexts, half of which were old. For each context, subjects indicated whether or not each context had been presented. The subject pool, materials, and apparatus were identical to that of the first two e:~periments, as was the procedure for the appropriate groups. Results and Discussion Mean response latencies were calculated as before. The overall pattern duplicated that observed in Experiment 2. No further tests were performed on these data. Recognition scores were computed for each subject and mean percent correct calculated across subjects for each condition. Recognition performance in the anomalous condition, 61.6~o, was significantly better than chance, t(11) = 5.09, p < .001, but only marginally worse than that of the context condition (68.3Yo), t(11)= 1.99, p<.10. Recognition memory for the sentence contexts was thus not impressive in either condition. The important point, however, is that recognition performance is not affected by whether subjects are expecting most of the sentences to make sense. Experiments 2 and 3 together indicate that having to read a sentence context has little

9

effect per se on lexical decision latency. Since there is apparently no difference between the no-prime and anomalous controls, and the anomalous condition at least makes the context and control tasks more similar, the anomalous control will be used for the subsequent comparisons and will be referred to simply as the control condition. We can now return to the question of the effect of dominance on latency. It was suggested before that facilitation should be a function of the predictability of the test word. To answer this question, the contexts were grouped into eight levels of dominance, with 12 contexts at each level. The mean dominance within levels ranged from .91 to .19. Mean c o r r e c t response latencies for the primary-word trials were calculated for each word, across subjects. This was done for both the context condition of Expel-merit 1 and the control condition of Experiment 2. Mean latency across sentences within each dominance level was then derived. These are shown in Table 3, along with means for the same words in the control condition. Only the highest dominance level (.91) was significantly different from the corresponding control condition, t(11) -- 6.76, p < .001. Since the mean for the control condition appeared somewhat higher (687msec) than that of the lower dominance levels, the significance of the high dominance facilitation was also tested against the no-prime data. Again, a significant facilitation was observed, t(11)=2.96, p<.01. The no-prime and anomalous conditions did not differ, t ( l l ) = 1.98, p<.10. Facilitation is thus limited to situations where the context strongly suggests a particular word, and that word is actually presented. The narrow range of stimuli facilitated supports an attentional interpretation of the effect, with subjects correctly generating only the most likely words. But if this were the case, then the latency to low-dominant primary test words, which would not typically be expected by subjects, should have been inhibited. This did not occur. One modification of the atten-

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FISCHLER AND BLOOM TABLE 3

MEAN LATENCY(IN MSEC)FOR PRIMARYWORDSOVEREIGHT PROBABILITYLEVELSAND FIVE EXPERIMENTALCONDITIONS Experimental conditions

Mean probability of primary word

2-sec context (Expt. 1)

No-prime control (Expt. 1)

Anomalous control (Expt. 2)

3-sec context (Expt. 4)

Suppression of context (Expt. 5)

91.5 78.3 66.4 55.4 48.7 37.5 28.8 19.3

553 606 668 637 634 634 667 654

638 641 705 677 604 623 737 665

687 625 634 623 646 645 667 614

584 598 671 609 610 652 720 659

599 609 640 620 621 664 655 673

TABLE 4 MEAN LATENCY(IN MSEC)AND ERROR RATE(IN PARENTHESES)FOR HIGH-DOMINANTVERSUSALL OTHER CONTEXTSOVER FOUR TYPES OF LEXICALDECISION TEST ITEMS Dominance level High (p= .92)" Type of test Primary words Unlikely words Anomalous words Primary nonwords

All others (,78 < p < A9)b

Context

Control

Context

Control

553 694 761 784

687 702 646 801

641 677 769 802

633 660 664 784

(.00) (.05) (.08) (.15)

(.00) (.05) (.03) (.05)

(.03) (.03) (.10) (.06)

(.04) (.03) (.02) (.08)

an = 12 sentences. bn = 84 sentences.

tional hypotheses is that subjects are sensitive to the dominance of a context, and only form and maintain expectancies when dominance is high. This predicts that latency for unlikely word trials should be inhibited, but only when a corresponding facilitation was observed for high-dominant words. The appropriate mean latencies were calculated, and are shown in Table 4, along with the corresponding means for primary word trials, for comparison. Clearly, there is no increase in latency at the high dominance level for unlikely word test

items, and unlikely word latency was not significantly different from the control latencies for the high dominance contexts. Table 4 also shows the latencies for the anomalous-word trials for high dominance contexts. Again, there is no evidence for increased inhibition with high dominance. Apparently, although facilitation is highly circumscribed, it is not purchased at the cost of inhibiting responses to other words. There was one other consequence of presenting a high-dominant context. The mean

EFFECTS OF CONTEXT ON WORD RECOGNITION

correct latencies and error rates for the primary-nonword trials are also given in Table 4. It can be seen that when a nonword was presented that closely resembled the primary word (e.g., STIMP for STAMP), correct latency did not increase, but the false alarm rate was substantially higher (15 versus 6~o) than that for the primary-nonword trials under lower dominance levels, which in turn did not differ from the error rate for unlikelynonword trials (5~o). A similar effect was reported by Marslen-Wilson and Welsh (1978), who found that the tendency to make phonemic restorations in a shadowed message increased with increasing contextual constraints. The effect of dominance on the various types of test items suggest two conclusions: First, the absence of any inhibition implies that once a word has been activated by the context, it remains readily available at no cost to other responses. That is, the facilitation is automatic. Second, the fact that facilitation is limited to a very narrow range of dominance shows that facilitation is not simply proportional to the predictability of the test word. The higher false-alarm rate for high-dominant words suggests that the presence of these nonwords did not produce an overall tendency for subjects to be more cautious and thus avoid such errors. This in turn suggests that the absence of facilitation for the other types of congruent word trials, compared to the control condition, did not result from a shift to a more rigorous response criterion in the context group. In this regard, it should be noted that the error rate on unlikely word trials is identical in the context and anomalous control conditions. In any event, such a criterion shift should affect all responses equally, and the particular advantage for high-dominance words, which was obtained within subjects, would still need to be explained. Since the primary and unlikely words were actually given as Cloze responses to the contexts, they were all "congruent" items, in

11

the sense that they were appropriate and reasonable completions of the sentences. Further, as we noted before, direct associations between context words and test words were avoided. It could be that the highdominance test words would be rated as more "related" to their contexts than would other test words. Thus, high-dominance items may be more "associated" to the context as a whole. But the Cloze procedure seems to us a more direct way of determining what the average subject's responses might b e - t h a t is, what words a context typically elicits-- while relatedness ratings are more post hoc judgments, presumably multidimensional in nature, regarding the "literative goodness" of particular responses. These judgments would seem, if not independent from Cloze probability, at least separable from it: Words could certainly be generated which would be unlikely Cloze responses, but which would be rated much more appropriate for a context than the "typical" Cloze responses. Finally, if the relatedness ratings for the present materials were indeed highly correlated to the Cloze probabilities, we would still be faced with the problem of explaining the particular dominance-facilitation function obtained. There are two possible reasons why only the contexts with dominance above .90 show facilitation. A contextual-latency hypothesis holds that although the 2-sec context duration and 500-msec stimulus interval was long enough to read and comprehend the basic meaning, the implications of the context, in terms of possible final words, could not be generated for any but the most dominant contexts. This extension of Marbe's Law, which holds that stronger associates are elicited more quickly than weaker associates, would seem to be reasonable, though we know of no data regarding the latency of Cloz'e responses. The second possibility, suggested above, is a reading-strategy hypothesis: Under normal reading conditions, a subject should not be able to accurately predict the particular word

12

FISCHLER AND BLOOM

that will be used in a given context. Aborn, Rubenstein, and Sterling (1959) showed that although the syntactic class of a final missing word was almost totally redundant (98~o agreement), the actual word that had been used in the original sentence was guessed only 25~ of the time. Skilled readers, then, may not typically generate particular expectancies, even though it may result in a slight facilitation of word recognition at no cost, because there is effort involved which may slow reading, and they simply will not be correct often enough for such a strategy to be worthwhile. A simple way to distinguish these possibilities in the present paradigm is to increase the duration of the context. The contextuallatency hypothesis predicts that as subjects are given more time to generate expectancies, facilitation will be observed at lower levels of dominance; the primary-word trials should show a significant overall facilitation and the facilitation should be more directly related to dominance. In contrast, the reading-strategy hypothesis predicts that the lower dominance levels will be unaffected. An additional context condition was run to distinguish these two hypotheses. EXPERIMENT 4 Method

Thirty introductory psychology students participated in the experiment for course credit. The same materials and apparatus used in the previous experiments were employed here. The procedure was also identical to that of the context condition of Experiment 1 except that the duration of the centext was increased 50% from 2 to 3 sec. The interstimulus interval remained at 500 msec. Results and Discussion

The mean latency for correct responses within the six tdst types was calculated for each subject. Mean latency across subjects is •shown in Table 1. Although the longer duration resulted in somewhat longer latencies

for nonword trials, the overall pattern of latencies is identical to that of Experiment 1. The additional time to examine the context, then, had no apparent effect on response latency to primary test words. A three-way analysis of variance comparing the 2-sec and 3-sec context conditions showed no effect of Group, F(1,58)<1.00. As before, Test Type had a significant effect on latency, F(2,116)=43.56, p<.001, as did Response, F(1,58)--91.86, p<.001. The interaction of Test Type and Response was also substantial, F(2,116)=80.56, p<.001. None of the interactions of Group with the other factors approached significance. Mean correct response latency for the eight dominance levels was calculated across sentences for the primary-word trials. These are shown in Table 3. As predicted by the readingstrategy hypothesis, the dominance functions for the two context conditions are nearly identical Pairwise comparisons across groups revealed no significant differences at any dominance level. Increasing the duration of the context did not alter the contextual effects observed in the initial experiments. The narrow range of facilitation produced is, therefore, not due to subjects having insufficient time to generate possible target words for the less dominant contexts. This suggests that after some minimal amount of processing (Cosky & Gough, Note 1; cf. Fischler & Bloom, Note 2), no further information is obtained from the context that will affect recognition of subsequent words. Since a great deal has been written about the usefulness of semantic context in reading, it was surprising to find that facilitation was so modest in terms of the range of words affected. The.conditions which would seem to be the best analogy to material encountered in normal reading, the unlikely-word and lowdominant primary-word trials, produced no effect at all on latency. As mentioned earlier, the absence of facilitation for the set of congruent test words as a whole contrasts with

EFFECTS OF CONTEXT ON WORD RECOGNITION

results of Schuberth and Eimas (1977). Since their stimuli were selected by the experimenters, and confirmed by judges, to be highly congruent with the context (e.g., "The puppy chewed the BONE"), it seemed likely that these words were also highly probable Cloze responses. However, we later found out (Schuberth, Note 3) that the overall Cloze probability of their test words was .12, which corresponds to the low end of the present range of dominance, and none of their contexts produced Cloze responses with dominance above .70. The present study differs from that of Schuberth and Eimas in several potentially important ways: The amount of facilitation and inhibition was assessed between groups; the distribution of Cloze responses was wider and better balanced; some nonwords were generated from high-dominant words (see above); the probability that a positive trial would be an anomalous one was .33, compared to .50 in Schuberth and Eimas' study; and subjects were not required to make an overt response to the context. Of these, we believe that the difference in Cloze probabilities is the likeliest source of the contrasting results. The presence of high-dominant responses may shift attention somewhat away from generally congruent to particularly likely responses, and counter any overall advantage gained by congruence. The absence of inhibition for the anomalous control condition is in a sense an extreme example of subjects' ability to respond to changes in the probability of certain types of trials. We are presently testing this hypothesis within congruent tests by varying the proportion of dominant test words presented. With a large proportion of high-dominant items, the unlikely word trials should produce significant inhibition, while in the absence of highdominant items, there should be facilitation for unlikely words. In any case, our conclusions regarding the scope and degree of facilitation must be considered tentative. We have suggested, in fact,

13

that there is no single answer to the first two questions raised at the outset, and that readers will make use of sentence contexts in a way that depends on the context in which the sentences themselves are embedded. EXPERIMENT 5

The final experiment concerns the degree to which subjects can deliberately control the contextual effects observed. The narrow range of words facilitated by context in these studies suggests that subjects generate particular response words for only high-dominant sentences. It has not been determined whether this limitation is a deliberate attentional strategy or is itself an automatic precess developed during years of reading. Also, it has been assumed to this point that the inhibition observed for words not conserving the meaningfulness of the context was due to an attentional focusing on a small semantic class of words. Support for this is found in a consideration of trials for the context and anomalous control conditions Of Experiments 1 and 2. In the context condition, subjects are seeing test words that do not make sense given the context, while other test words do make sense. Thus, when subjects cannot predict when meaningfulness will be conserved, a substantial inhibition is obtained. When no context makes sense, this inhibition disappears. This strongly implies that subjects can control the inhibition, One unanswered question, however, concerns the purpose of the inhibition. The overall positive latency is slower with context than without it, despite the fact that the context and test form reasonable sentences on two-thirds of the positive trials. If inhibition is under a subject's control, and there is no overall benefit from the context in this situation, it would seem that subjects should simply stop forming expectancies about the meaning of the sentence. In Experiment 5, an attempt was made to determine if either the facilitation of particular words or the inhibition of anomalous words

14

FISCHLER A N D BLOOM

could be controlled simply by instructions not to form expectancies about the sentence. This was done by telling subjects that although the test words would typically make sense given the context, they should ignore this relationship, and suppress as best they could their expectancies about the imminent test. Method Subjects. Thirty-two introductory psychology students participated in Experiment 5 for course credit. Two subjects were deleted from further analysis because of excessive errors. This left 30 subjects in what will be referred to as the suppression group. Materials and apparatus. The same materials and apparatus used in the last experiment were employed in Experiment 5. Procedure. Subjects received instructions identical to those of the context subjects of Experiments 1 and 4, except that they were told to try to treat the reading of the sentence and the subsequent lexical decision as two separate tasks and, after reading the sentence context, to avoid generating any expectancies about the test item. After completing this part of the experiment, subjects were given a recognition test identical to that used in Experiment 3. Results and Discussion ~

The mean recognition score across subjects in the suppression group was 68.7~o correct. Recognition scores for the first 12 subjects were compared to those for the 12 context subjects in Experiment 3. A t test indicated no significant difference between the two groups, t ( l l ) = 1.67, p<.10. The subjects in the suppression condition were, therefore, reading the sentences as instructed. Mean latencies for the six test types were calculated across subjects as before, and are shown in the final column of Table 1. The results are nearly identical with those of the context condition of Experiment 1, with the exception of the anomalous word trials, which appear to be somewhat faster than those of the

context condition (739 versus 768 msec). Error rates also were similar to those of the context group, but with a slightly lower error rate for anomalous word trials. In order to assess whether the instructions decreased the contextual effects at all, an analysis of variance was performed comparing the suppression and context groups. There was no main effect of Group, F(1,58)< 1.00, but significant main effects of Response, F(1,58)=119.64, p<.001, and Test Type, F(2,116)=49.24, p<.001. The Response by Test Type interactions was significant, F(2,116)=43.71, p<.001. None of the interactions involving Group approached significance. The mean latency for correct primary-word trials was calculated for each of the eight dominance levels, as before. These data are shown in Table 3. As with the context condition, the shortest latencies were obtained with the two highest-dominance contexts. There appeared to be somewhat less facilitation for the high dominance level in the suppression than in the context group (599 versus 553 msec), but the suppression latency for high dominance was still significantly faster than that of the control condition, t(11)=3.50, p<.005. No other dominance level was significantly different from the control. If thus appears that subjects could not suppress the semantic implications of a sentence context which had just been read. Both the facilitation for high dominance contexts and the inhibition for anomalous words was obtained, although both effects seemed somewhat diminished. To assess whether some subjects were better able than others to suppress the contextual effects, the suppression group was divided first on the basis of the recognition scores, and then on the basis of verbal reports obtained at the end of the session. High Recognition (n= 15) was defined as greater than the median of 69~o correct. The means are shown in Table 4. A two-way analysis of variance was performed

EFFECTS OF CONTEXT ON WORD RECOGNITION

15

TABLE 5 MEAN LATENCY(IN MSEC)FOR THREE TYPES OF LEXICALDECISIONTEST ITEMSACROSSRECOGNITION PERFORMANCEAND ACROSS RATED EXPECTANCY Division of subjectsa Recognition score b Type of test Primary words Unlikely words Anomalous words

Rated expectancy c

High

Low

High

Low

608 (22)d 651 (22) 708 (25)

663 (36) 704 (45) 770 (46)

595 (23) 614 (15) 688 (25)

670 (47) 731 (56) 782 (61)

aDerivation of subgroups is described in the text. bn = 15. Cn=9. dStandard error of means by subject.

on latencies for words only, with Group (high, low recognition) and Test Type as factors. There was a significant main effect of Test Type, F(2,56)=43.82, p<.001, but the main effect of Group and the interaction between Group and Test Type were not significant, F(1,28)=1.48, p>.20, and F(2,56)<1.00, respectively. The slight reduction in contextual effects for the suppression condition is clearly not due to a failure of some subjects to consistently read and comprehend the contexts. After the experiment was over, subjects were asked to what extent they generated expectations about what the lexical decision stimulus would be. Eighteen of the 30 subjects were then divided into two groups: high expectancy (more than 50~o) and low expectancy (less than 25~o of the sentences). The means are shown in Table 5. A 2 x 3 analysis of variance was done on latencies for words only, with Group (high and low expectancy) and Test Type as factors. Although there was a significant effect of Test Type, F(2,32) = 28.13, p<.001, the main effect of Group and the interaction between Group and Test Type were not significant, F(1,16)=2.84, p>.10, F(2,32)=1.16, p>.20. Thus, subjects in the suppression condition are influenced by the

context regardless of their reported expectancy level. The critical point is that subjects who were, by their own assessment, better able to follow the instructions and thus suppress their expectancies still exhibited the effects of the contexts. There seems to be no reason to doubt the earnestness of subjects in trying to follow the instructions of Experiment 5. It must be concluded that, faced with test items which are for the most part making sense given the context, subjects cannot simply choose to ignore the relationship between the context and the test item, even when there is no advantage to be gained by forming such expectancies. Yet it can be ignored when the "metacontext" indicated that anomaly was the norm. The implication of these two facts for understanding the nature of inhibition, and of automatic processes, will be discussed below. GENERAL DISCUSSION

The effect of a sentence context on lexical retrieval has been shown to involve both facilitation and inhibition of a range of test words. Although this replicates the effects of such contexts on visual thresholds (Tulving, Mandler, & Baumal, 1964), and on lexical

16

FISCHLER AND BLOOM

decision (Schuberth & Eimas, 1977), it is clear that these effects involve mechanisms more complex than the raising or lowering of the availability of a word as a function of the probability of its occurrence. First, whether compared to a no-prime or an anomalous control, there is substantially less facilitation for appropriate words than inhibition of inappropriate words. The ability to respond to a large set of words--apparently, all words except those which may reasonably complete a sentence-- is significantly inhibited by the context, while response to words which are perfectly meaningful in a given context but have very low probabilities of occurrence are not affected at all. Moreover, within the set of appropriate words, as the probability or dominance is increased, there is no corresponding proportional decrease in latency until the probability approaches certainty. Facilitation and inhibition are, at least in the present paradigm, far from symmetric effects. The facilitation produced for high-dominant contexts, though narrow in range, did not appear to have the other characteristics of an attentional process. Such contexts did not produce a corresponding inhibition of unlikely words, nor was the facilitation affected by increasing the time available for generation of expectancies. Finally, subjects could not avoid the effect when instructed to do so, another characteristic of an automatic process. The inhibition of anomalous words is unusual in two respects, given current theories of attentional inhibition (e.g., Posner & Snyder, 1975a). First, it seems to be a cost without a benefit; that is, the substantial inhibition of inappropriate words is not associated with a corresponding facilitation of appropriate but unlikely words. Second, the inability of subjects, given the suppression instructions, to eliminate the inhibition suggests that the concept of attentional mechanisms as being under a subject's active control needs to be revised. As Neely (Note 4) has pointed out, subject expectancies are typically confounded with practice when the probability of various

events is manipulated (see Ollman, 1977). The presence of inhibition in the suppression condition, together with the absence of inhibition in the anomalous control condition, suggests that the particular events that a subject has been dealing with, such as whether or not any of the sentences he is seeing makes sense, may override any conscious intentions about the task. Similarly, Neely (Note 4) found that the effect of word frequency on lexical decision time depends on the relative proportion of high- versus low-frequency words prior to a critical trial. Explicity telling subjects to expect a high- or low-frequency-test, in contrast, had little effect on performance. Although there are obviously more complex situations where attention can be consciously directed to one aspect of a task at the cost of another (e.g., shadowing one of two messages), this level of control may be difficult to bring to bear on overlearned skills such as the comprehension of sentences and the recognition of words. A recent study by West and Stanovich (1978) indicates that under some circumstances, a sentence context may produce facilitation for some words without a corresponding inhibition for words incongruent with the context. In their experiment, readers of three ages had to pronounce a word which had been preceded by a congruent or incongruent context, or by a neutral signal. The stimuli were selected by the experimenters, in a manner similar to that of Schuberth and Eimas (1977). For fourth- and sixth-grade readers, pronunciation latency was facilitated by a congruent context and inhibited by an incongruent context. For adult readers, however, only the facilitation was obtained. West and Stanovich argued that for the adult reader, word recognition had become automated to the extent that only the rapid, facilitatory effects of context would be obtained. Since the materials and design of the West and Stanovich experiment differ substantially from that of the present research, it is difficult to determine why inhibition was

EFFECTS OF CONTEXT ON WORD RECOGNITION

obtained in our study and not in theirs. A reasonable speculation, however, is that the respective tasks used in the two studies involve different aspects of word recognition. Coltheart (1979) recently reviewed the issue of lexical access and grapheme-phoneme translation, and concluded that the particular requirements of the task may determine whether or not a phonemic representation must precede lexical access. For young readers, a phonemic code may be a more integral part of word recognition than it is for adults. A pronunciation task for children might then be speeded by appropriate, or slowed by inappropriate, contexts. For adult readers, phonemic and lexical codes may be derived in parallel. If we assume that lexical access is somewhat faster than phonemic translation (Forster & Chambers, 1973), then with congruent contexts, the lexical route is speeded, and faster times are obtained. With incongruent contexts, the lexical route is slowed but the grapheme-phoneme route is una'ffected. This would produce inhibition of a lexical decision but no inhibition of pronunciation speed. This argument suggests that the lexical decision task is more appropriate than the pronunciation task for studying the effects of context in skilled reading (see also Fischler & Goodman, 1978), since phonemic representation of a word may not be an essential part of word recognition, while lexical access must be. The longer latencies associated with the lexical decision task may be more of a reflection of the lack of practice with such a task, as compared to grapheme-phoneme translation, than of the priority of phonemic over lexical codes. The lexical decision task is, of course, superficially quite different from the task of reading. One seldom encounters nonwords in prose, and therefore assumes, rather than decides, that each string of letters constitutes a word. Also absent in the present task is the need to relate the current sentence to the structure of a larger information context, and

17

the ability to use that larger context to place further constraints on the range of possible test words. Finally, a reader seldom reads a sentence up to the last word, waits, then tries to recognize the final word. Nonetheless the processes of direct interest here--the retrieval of words from an internal lexicon and the influence of a context on that retrieval--are shared by the present task and reading. In both cases, an item must be recognized as a lexical unit before further linguistic processesing can occur. Second, this recognition appears to necessarily involve the elicitation of semantic information associated with the lexical item (James, 1975; Shulman, Hornak, & Sanders, 1978). The effects of context observed here may then be understood by considering the relationship of the present task requirements to those of reading. It was thought that the three types of test words used captured the kind of situations a person might be expected to encounter during normal reading. Most often, each successive word would conserve the overall meaning of the sentence, as did the primary and unlikely test words. Also, one can rarely predict with high accuracy the particular word encountered. Despite the costfree facilitation such prediction apparently provides, the infrequency of high-dominance contexts means that such activity would be of little benefit in expediting reading. A person would be wise to develop a strategy which avoids the conscious anticipation of particular words. In contrast, a person cannot afford n o t to assess the semantic coherence of a passage as each new unit is analyzed. In both reading and listening, semantic anomaly is highly informative, indicating that an error may have been made, either in understanding the context or perceiving the new unit. There will also be situations, particularly when new, unexpected or metaphoric ideas are being described, where nothing has gone wrong, but the reader needs to stop the flow of information and try to determine why the word appeared to be

18

FISCHLER AND BLOOM

anomalous (Hoffman, Note 5). In either case, the anomaly is less a hindrance to responding than a signal that something must be done. From the reader's point of view, then, the response to anomalous words is more like an orientation than an inhibition: Semantic anomaly is unexpected and requires further action. The inhibition observed here may, therefore, be a cost without a benefit only in terms of word retrieval. Moreover, even this "cost" would be minimal, since the proportion of anomalous words used here is substantially higher than would typically be encountered in prose, and the magnitude of the inhibition even with a high proportion of anomalous trials would be small compared to other ongoing processes. The presence of both facilitation and inhibition of test words here suggests at least a superficial similarity between associative priming and sentence priming. The processes involved in the two situations, however, are unlikely to be identical. There is an obvious difference in the degree of processing required" for a single-word associate (e.g., CAT) versus a sentence context (e.g., "He tried to put the new collar on his") to influence a test word (e.g., DOG). The sentence has no single word strongly associated with the test word; in addition, there may be "configural" aspects of the sentence (e.g., Foss & Harwood, 1975) not obtainable from the meaning of the individual words. Hence, priming effects can be obtained with single words when the prime precedes the test word by as little as 40msec (Fischler & Goodman, 1978), while the words of sentence contexts must be displayed for a considerably longer time (Cosky & Gough, Note 1) t o influence word recognition. We have argued that readers are not typically generating particular responses to sentence contexts. De.spite the differences between the present results and those obtained by Schuberth and Eimas (!977), in neither case were unlikely but congruent words significantly slower than the control condition,

which would be the case if subjects were actually expecting particular words: If the probability that a subject generates the correct word is 20~, then 80~o of the time subjects will be expecting the wrong word, and inhibition should occur. In both studies, then, attention seems more directed to the class of words which conserve meaning. A similar argument can in fact be made for single-word priming studies. The average associative probability of items used in associative priming studies is typically less than 50~, with particular pairs often below 25~ (e.g., 17~ for DOCTOR-NURSE, according to the Keppel & Strand (1970) norms). In these studies, then, subjects are also likely to be wrong in predicting particular responses. It would seem that in both cases, attention (to whatever extent it is engaged in predictive activity in these tasks) is directed more to a class of words related in some semantic category (for associates) or episodic idea (for sentences) than to particular words. Other evidence for this claim in the associative-priming studies comes from Neely's (1977) observation that category dominance had no effect on degree of facilitation, and Fischler's (1977b) failure to find a correlation between associative strength and amount of facilitation. A reasonably complete description of how sentence contexts may be used in word recognition and reading has been outlined here. It is worth noting in conclusion that this description depended in part on combining an explicit information-processing model which distinguishes automatic and attentional processes, with an experimental manipulation of redundancy. Although structural linguistic variables must play a role in contextual effects, we are led tO believe, with Keele (1973), that measures of the quantity of information provided by a stimulus can be as important as more qualitative and structural factors in understanding performance.

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MARSLEN-WILSON, W. D., & WELSH, A. Processing interactions and lexical access during word recognition in continuous speech. Cognitive Psychology, 1978, 10, 29-63. MEYER, D. E., & SCHVANEVELDT, R. W. Facilitation in recognizing pairs of words: Evidence of a dependence between retrieval operations. Journal of Experimental Psychology, 1971, 90, 227-234. MILLER, G. A., & ISARD, S. Some perceptual consequences of linguistic rules. Journa[ of Verbal Learning and Verbal Behavior, 1963, 2, 217-228. MORTON, J. The effects of context on' the visual duration thresholds for words. British Journal of Psychology, 1964, 55, 165-180. MORTON, J. Interaction of information in word recognition. Psychological Review, 1969, 76, 1.65M78. NEELY, J. H. Semantic priming and retrieval from lexical memory: Evidence for facilitatory and inhibitory Processes. Memory& Cognition, 1976, 4, 648-654. NEELY, J. H. Semantic priming and retrieval from lexicaI memory: Roles of inhibitionless spreading activation and limited-capacity attention. Journal of Experimental Psychology: General, 1977, 106, 226-254. OLLMAN, R. Choice reaction time and the problem of distinguishing task effects from strategy effects. In S. Dornic (Ed.), Attention and performance VI. Hillsdale, N. J.: Lawrence Erlbaum, 1977. PosN~, M. I., & SNYDER, C. R. R. Attention and cognitive control. In R. L. Solso (Ed.), Information processing and cognition. Hillsdale, N. J.: Lawrence Erlbaum, 1975. (a) POSNER, M. I., & SNYDER, C. R. R. Facilitation and inhibition in the processing of signals. In P. M. A. Rabbitt & S. Dornic (Eds.), Attention and performance V. London: Academic Press, 1975. (b) SCHNEIDER, W., & SHIFFRIN, R. M. Controlled and automatic human information processing: I. Detection, search and attention. Psychology Review, 1977, 84, 1-66. SCHUBERTH, R. E., & EIMAS, P. D. Effects of context on the classification of words and nonwords. Journal of

Experimental Psychology: Human Perception and Performance, 1977, 3, 2236. SCHVANEVELDT,R. W., & MEYER,D. E. Retrieval and comparison processes in semantic memory. In S. Kornblum (Ed.), Attention and peJformance IV. New York: Academic Press, 1973. SHULMAN,H. G., HORNAK, R., & SANDERS,E. The effects of graphemic, phonetic, and semantic relationships on access to lexical structures. Memory & Cognition, 1978, 6, 115-123. TAYLOR, W. L. "Cloze" procedure: A new tool for measuring readability. Journalism Quarterly, 1953, 30, 415. TULVING, E., & GOLD, C. Stimulus information and

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REFERENCE NOTES contextual information as determinants of tachistoscopic recognition of words. Journal of Experi1. COSKY,M., & GouGrl, P. B. The effect of context on mental Psychology, 1963, 66, 319-327. word recognition. Paper presented at the meeting of TULVlNG,E., MANDLER,G., & BAUMAL,R. Interaction of the Midwestern Psychological Association, Chicago, two sources of information in tachistoscopic word May 1973. recognition. Canadian Journal of Psychology, 1964, 2. FISCHLER, I., & BLOOM, P. A. Effects of rapidly 18, 62-71. presented contexts on word retrieval in reading. Paper TWEEDY, J. R., LAPINSKY, R. H., & SCHVANEVELDT, presented at the meeting of the Southeastern R. W. Semantic-context effects on word recognition: Psychological Association, Atlanta, March 1978. Influence of varying the proportion of items presented in an appropriate context. Memory & 3. SCHUBERTH,R. E. Personal communication, June 18, 1978. Cognition, 1977, 5, 84-89. 4. NEELY, J. E. Personal communication, November, WEBER, R. M. First grader's use of grammatical context 1977. in reading. In H. Levin & J. P. Williams (Eds.), Basic 5. HOFFMAN,R. R. Conceptual base hypothesis and the studies on reading. New York: Basic Books, 1970. problem of anomalous sentences. Paper presented at WEST, R. F., & STANOYICH,K. E. Automatic contextual the meeting of the American Psychological Associfacilitation in readers of three ages. Child ation, San Francisco, August, 1977. Development, 1978, 49, 717-727. WtNER, B. J. Statistical principles in experimental design. (Received June 2, 1978) New York: McGraw-Hill, 1971.