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The contexts of plausible denial
~OURNAL OF VERBAL LEARNING AND VERBAL BEHAVIOR 4~
7-11 (1965)
The Contexts of Plausible Denial 1 P. C. WASON Medical Research Council, Industrial Psychology Research Unit, University College, London This investigation is designed to determine whether pragmatic factors in language affect the time taken to respond to negative statements. In assertive discourse the function of such statements is generally to emphasize that a fact is contrary to an expectation. The subjective context for their utterance is the assumption that another person, or persons, might classify a fact wrongly. This investigation, however, is concerned solely with possible objective contexts of plausible denial, i.e., with the characteristics of facts which can be readily denied irrespective of the attempt to communicate them. In the absence of context it takes longer to respond to negative statements than to affirmative ones, even when' the amount of information conveyed by the statements is equated (Wason, 1961), and when neutral signs, substituted in the statements for "is" and "isn't," are interpreted in terms of affirmation and denial (Wason and Jones, 1963). Recent research by Miller and his students 1 This research was carried out while the author was a Research Fellow in Cognitive Studies at Harvard University, 1962-1963, on leave of absence from the Medical Research Council. The investigation was supported by a grant from the National Foundation (No. NSF G-16486) to Harvard University, Center for Cognitive Studies. I am particularly indebted to Professor George A. Miller for his interest and for a most helpful criticism of the argument. Grateful acknowledgments are also due to Dr. R. J. Audley and Dr. A. R. Jonckheere for thorough discussion of methodological and statistical problems, to Dr. Harris Savin for help with the apparatus, and to Miss Susan Carey for conducting the experiment and assisting with the computation.
on the psychology of grammar has shown that both syntactic and semantic factors affect this phenomenon. I t has been demonstrated (Miller, 1962) that, given two lists of sentences in various grammatical forms, it takes longer to match affirmatively expressed sentences with the correlative negative sentences than to match the affirmative sentences with the identical sentences. But is was also shown that it takes even longer to match sentences expressed in the active voice with correlative sentences in the passive voice. The results were in good agreement with predictions based on a hypothesis concerned with the psychological relevance of "transformational grammar" (Chomsky, 1957), i.e., a grammar in which sentences of any grammatical complexity are regarded as being generated by the successive application of transformation rules to simple, active, declarative sentences. It would appear that the response latency to negative statements is some function of grammatical structure. The matching task used in Miller's experiment, however, was designed to reflect only the syntactic level of language; the truth or falsity of the sentences was irrelevant to their identification. McMahon (1963) has shown that, when sentences of differing grammatical complexity have to be evaluated as true or false, the results are consistent in general with a theory of transformations, with three exceptions concerning negatives. (1) The evaluation time for negative sentences was considerably longer than that for passive sentences. This result has been corroborated by Slobin with children as Ss (Slobin, 1963).
8
WASON
(2) Sentences containing the preverbs "always" and "never" (e.g., "13 always follows 5," "5 never follows 13") differed significantly in evaluation time in spite of the fact that no negative transformation of a syntactical kind is involved. (3) When a delay was introduced between the presentation of a sentence and the stimulus necessary to evaluate it, the time taken to store the sentence, which was self-paced by the Ss, reflected the syntactical transformations involved. Only the negative transformation, however, and not the passive one, affected the time taken to evaluate the sentence as true or false. These exceptions indicate that, at the semantic level of truth and falsity, negation exercises additional effects. I n the present experiment two related but independent hypotheses about the objective contexts of plausible denial are postulated: the exceptionality hypothesis and the ratio hypothesis. The exceptionality hypothesis is as follows: Given a set of similar stimuli, xl, x2 . • • Xn, and a stimulus, y, which is perceived to differ from these in one important attribute, it is more plausible to assert that y is not x than to assert that xi is not y. For example, the statement to a child, "a whale is not a fish," would usually be more illuminating than the statement, "a herring is not an animal." A whale might be wrongly classified as a fish, b u t a herring would hardly be classified as an animal. Similarly, the statement, "the train was not late this morning," would obviously be more pertinent when the train is normally late than when it it normally punctual. The ratio hypothesis is as follows: Given two sets of stimuli which differ considerably in magnitude, it is more plausible to deny that the smaller set possesses a property of the larger set than to deny the converse. For example, the two statements, "of the eight contributions, one is not in Class l " (said with reference to insurance contributions),
and "one quarter of this square'is not red," seem intrinsically plausible ways of describing two facts. On the other hand, negative reference to the larger set seems more strained: "of the eight contributions, seven are not in Class 1 , " "three quarters of this square is not red." I n discourse, of course, the contexts defined in these hypotheses frequently occur together. The tasks used were designed to separate them by varying the way in which the same series of abstract stimuli is described. METttOD
Design. The experimental conditions used to test both hypotheses were four types of statement, each associated with a stimulus consisting of similar items (seven circles in the same color) and a dissimilar item (one circle in a different color): (1) affirmative statements about the color of the dissimilar item (DA); (2) negative statements about the color of the dissimilar item (DN); (3) affirmative statements about the color of a similar item (or items) (SA); (4) negative statements about the color of a similar item (or items) (SN). These conditions were presented in a series of 24 trials to two groups: an Exceptionality group (to test the exceptionality hypothesis) and a Ratio group (to test the ratio hypothesis). In both groups it was predicted that the difference between the time taken to respond to negative and affirmative statements about the color of the dissimilar items would be less than the corresponding difference for statements about the similar items, i.e., (DN - - DA) < (SN - - SA). The serial order of the conditions was counterbalanced in accordance with a previous design (Wason, 1959), each type occurring once in a different order for each S in every block of four trials, making a total of six presentations of each condition. Tasks. Only two colors were used in the stimuli: blue and red. Hence every sfimtilus consisted of either seven red items and one blue, or seven blue items and one red. Each trial had three successive phases. Exceptionality group: (1) The stimulus, in which the items were numbered consecutively from one to eight, was exposed for 3 sec; (2) the Ss were instructed to describe the stimulus aloud in their own words so that it could be identified, e.g., "circle No. 4 is blue and the rest are red"; (3) one of the four types of statement, referring to a specific
CONTEXTS OF PLAUSIBLE DENIAL item in the stimulus was presented, with the predi~ cate omitted, e.g., "circle No. 7 is . . . ," "circle No. 4 i s not . . ." The Ss responded with the color (blue or red) affirmed, or denied, of the item mentioned. The response was timed. Ratio group: (1) The treatment was the same as that in the Exceptionality group, but the items were not numbered; (2) the Ss were instructed to state aloud the number of items in each color, e.g., "seven circles are red and one is blue"; (3) the treatment was the same as that in the exceptionality group, but the statements were as follows: "exactly one circle is . . . . ," "exactly one circle is not . . . ," "exactly seven circles are . . . ," "exactly seven circles are not . . . . " Subjects. The Ss, 48 paid volunteers (35 women and 13 men), were students attending a summer school at Harvard University. They were assigned alternately to the groups and tested individually. Material. Twenty-four sets of stimuli were made for each group, the dissimilar item in each set appearing as red and as blue twice in each of the possible positions in the stimulus array except the first and eighth. The eight items were 0.2~ inch in diameter and were pasted on cards 6 X 4 inches in length in two rows of four. They were presented to a quarter of the Ss in a randomly determined order; to a quarter in the reverse of this order; to a quarter in the original order with colors interchanged; and to a quarter in the reverse Of this order. In the Exceptionality group 24 statements (each typed on cards 6 )< 4 inches in length) were matched with the 24 stimuli under the following constraints: (1) each of the four types of statement referred once to an item in each of the possible positions in the array except the first and eighth; (2) the correct response was blue on half the trials in every block of four and red on the other half. Only the latter constraint applied in the Ratio group where the four standard statements were each repeated six times. Procedure. At each trial the material was placed on a moving belt behind an apparatus. By depressing a switch /~ brought the stimulus into line with an aperture in front of the S; a second switch was then depressed to illuminate the stimulus and start a timer. After 3 sec. a third switch w a s depressed which removed the stimulus, stopped the timer,
9
and brought the statement into line with the aperture. The S's description of the stimulus was recorded by a second E and the timer was reset. The second switch was then depressed again to expose the statement and start the timer. The S responded by pressing either a key marked red, or a key marked blue (on the left and right of the apparatus, respectively), which stopped ' the timer and removed the statement. A pilot light informed R of the response. The time, to the nearest 0.01 sec, was recorded, t~)gether with the response. The material for the next trial was then loaded, that from the previous. one having been automatically ejected. The Ss were instructed in the sequence of events and were shown examp!es of the stimuli and statements. They were told they would be timed but were warned not to sacrifice accuracy for speed. Finally, they were trained in giving the responses by pressing the keys in answer to a random sequence of the words "blue" and "red" spoken by E. RESULTS
The Hypotheses. T h e m e a n r e s p o n s e t i m e to e a c h
c o n d i t i o n was
computed
for e a c h
S ( N --- 6). T a b l e 1 gives t h e m e a n of t h e s e values for b o t h g r o u p s ( N ~
24), t o g e t h e r
w i t h t h e m e a n n u m b e r of errors ( N z The prediction, (DN --DA)
<
144).
(SN -- SA),
was t e s t e d b y c a l c u l a t i n g t h e i n t e r a c t i o n Q, where
Q ~-~ ( S N - - S A )
-- (DN--DA),
for
e a c h S. T h e d i s t r i b u t i o n of Q was n o r m a l in the Exceptionality group and approximately n o r m a l in t h e R a t i o g r o u p . Scores a s s o c i a t e d w i t h errors w e r e n o t r e j e c t e d f r o m t h e c o m p u t a t i o n . W i t h o u t e r r o r s the m e a n s of t h e c o n d i t i o n s d e c r e a s e d on a v e r a g e b y 0.0.2 sec in t h e E x c e p t i o n a l i t y g r o u p a n d b y 0.06 sec in t h e
Ratio
group.
In
the Exceptionality
g r o u p Q - - + 0 . 2 5 sec ( r e l a t e d m e a n t - - 2.59, p < .01, o n e - t a i l e d ) ; in the R a t i o g r o u p Q - - - 0 . 1 6 sec (1'elated m e a n t ~
1.01, n o t sig-
n i f i c a n t ) . H e n c e , on t h e a s s u m p t i o n t h a t t h e effects o f t h e c o m p o n e n t s of t h e c o n d i t i o n s
TABLE 1 MEAN lk~SPONS~ TI~ES (SEC) AND MEAN NUMBER OF ERRORS Ratio group
Exceptionality group
Resp. time Errors
DA
DN
SA
SN
DA
DN
SA
SN
1.60 0.05
1.96 0.08
1.93 0.03
2.53 0.11
1.60 0.08
2.51 0.08
1.68 0.08
2.44 0.08
I0
WASON
are additive, the exceptionality hypothesis is .01) between the values of (DN - - DA) confirmed and the ratio hypothesis is not in the two groups. Inspection of Table 1 shows confirmed. On the alternative assumption that this result is entirely due to the difference that the effects of the components are multi- in response times to DN (1.96 sec in the plicative rather than additive, the individual Exceptionality group and 2.51 sec in the observations were converted into log trans- Ratio group), the response times to DA being forms. The same results were obtained with the same (1.60 sec). these transformed scores, b u t t h e exceptionThe DN statements have the same denotaality hypothesis was confirmed at only the tion in both groups, but they differ in the 0.025 confidence level. way in which the negated property, which Comparison between Groups. The mean is given as the response, has been coded in value of (DN - - DA) in the Ratio group the initial description of the stimulus. Con(+0.91 sec) was significantly greater than sider a stimulus in which the dissimilar item the corresponding value in the Exceptionality is blue and the similar items are red. In the group ( + 0 . 3 6 sec) (t -7- 3.49, p < .01), Exceptionality group the property negated in but the mean values of (SN - - SA) did not the statement would have been initially differ significantly. ( T h e same results were affirmed of a residual class which does not exist independently of the dissimilar item: obtained on the log transforms.) Initial Descriptions. In the Exceptionality "the rest are red." But the dissimilar item group 19 Ss consistently coded the stimuli in would, of course, cease to be an exception terms of an exceptional item followed by a without this residual class. The dissimilar residual class, e.g., ~'-'circle No. 4 is blue and item is the dominant feature and the residual the rest are red." Three Ss consistently men- class in the subsidiary feature, but the two tioned the exception last, e.g., "all the circles are reciprocally related. On analogy with are red except for No. 4 which is blue," perceptual phenomena, the dissimilar item and two Ss oscillated between the two kinds is the figure and the residual class is the of coding. In the Ratio group 16 Ss consist- ground against which the figure is coded as ently mentionbd the dissimilar item last, e.g., ari exception. In the Ratio group, on the "seven circles are red and one is blue," six other hand, the dissimilar item is negated consistently inverted this order, and two were in terms of a property which would have inconsistent. In both groups the mean re- • been initially affirmed of a discrete class which sponse times of the Ss, who consistently men- does have an independent existence: "seven tioned the dissimilar item last, were less on circles are red." These differences between the groups in all four conditions than the mean of those who consistently mentioned it first. The num- the initial coding suggest that the ease or bers are, of course, t~oo small to determine difficulty involved in denying a property of whether this result is a function of the order a class is a function o,f the formal characin which the items were described. It is clear, teristics of the contrast class of which the however, that this variable has no differential property is, explicitly or implicitly, predicated. The more this contrast class is pereffects on the response to the conditions. ceived, o r coded as subsidiary to the class DISCUSSION of interest, the more readily can its property The result which gives some insight into be abstracted and negated with respect to the confirmation of the exceptionality hypoth- the class of interest. The relevant variables esis and the nonconfirmation of the ratio cannot be more accurately defined until further -work has been done. The problem, in hypothesis is the tmpredicted difference (p <
CONTEXTS
OF P L A U S I B L E D E N I A L
general, is to isolate the distinctive features of descriptions which predispose a person to assent to a negative statement. The present investigation has shown that contextual variables associated with the concept of exceptionality affect the response to negation, in addition to the syntactic and semantic variables identified by Miller and his associates. I t is a task for the future to determine the contextual parameters which interact with the response to other grammatical categories. SUMMARY Two hypotheses were tested about the contexts which facilitate response to negative statements. The same" series of stimuli, each stimulus consisting of seven similar items and one dissimilar item, was described by two independent groups in differing terms. The dependent variable was the time taken to complete a statement presented immediately after each stimulus had been described. When the stimuli are described in terms of an exceptional item and a residual class, the response to negative statements is facilitated, if these statements deny that the exceptional item possesses the property of the residual class.
11
On the other hand, when the stimuli are described in terms of a smaller and a larger class, no facilitation of response to the corresponding negative statements is observed. I t is hypothesized that the determining factor in these results is the way in which the negated property is coded in the descriptions of the stimuli. REFERENCES
CHOIVISKY~ N. Syntactic structures. The Hague: Moulton & Co., 1957. MCMAHON, L. E. Grammatical analysis as part of understanding a sentence. Unpublished doctoral dissertation, Harvard University, 1963. MILLER, G. A. Some psychological studies of grammar. Amer. Psychologist, 1962, 17, 748-762. SLOBIN, D. I. Some psychological aspects of grammatical transformations in childhood and adulthood. Unpublished doctoral dissertation, Harvard University, 1963. WAsoI% P. C. The processing of positive and negative information. Quart. ]. exp. Psychol., 1959, 11, 92-107. WASON, P. C. Response to affirmative and negative binary statements. Brit. ]. Psychol., 1961, 52, 133-142. WASON, P. C., AND JON~S, S. Negatives: denotation and connotation. Brit. ]. Psychol., 1963, 54, 299307. (Received January 28, 1964)
7-11 (1965)
The Contexts of Plausible Denial 1 P. C. WASON Medical Research Council, Industrial Psychology Research Unit, University College, London This investigation is designed to determine whether pragmatic factors in language affect the time taken to respond to negative statements. In assertive discourse the function of such statements is generally to emphasize that a fact is contrary to an expectation. The subjective context for their utterance is the assumption that another person, or persons, might classify a fact wrongly. This investigation, however, is concerned solely with possible objective contexts of plausible denial, i.e., with the characteristics of facts which can be readily denied irrespective of the attempt to communicate them. In the absence of context it takes longer to respond to negative statements than to affirmative ones, even when' the amount of information conveyed by the statements is equated (Wason, 1961), and when neutral signs, substituted in the statements for "is" and "isn't," are interpreted in terms of affirmation and denial (Wason and Jones, 1963). Recent research by Miller and his students 1 This research was carried out while the author was a Research Fellow in Cognitive Studies at Harvard University, 1962-1963, on leave of absence from the Medical Research Council. The investigation was supported by a grant from the National Foundation (No. NSF G-16486) to Harvard University, Center for Cognitive Studies. I am particularly indebted to Professor George A. Miller for his interest and for a most helpful criticism of the argument. Grateful acknowledgments are also due to Dr. R. J. Audley and Dr. A. R. Jonckheere for thorough discussion of methodological and statistical problems, to Dr. Harris Savin for help with the apparatus, and to Miss Susan Carey for conducting the experiment and assisting with the computation.
on the psychology of grammar has shown that both syntactic and semantic factors affect this phenomenon. I t has been demonstrated (Miller, 1962) that, given two lists of sentences in various grammatical forms, it takes longer to match affirmatively expressed sentences with the correlative negative sentences than to match the affirmative sentences with the identical sentences. But is was also shown that it takes even longer to match sentences expressed in the active voice with correlative sentences in the passive voice. The results were in good agreement with predictions based on a hypothesis concerned with the psychological relevance of "transformational grammar" (Chomsky, 1957), i.e., a grammar in which sentences of any grammatical complexity are regarded as being generated by the successive application of transformation rules to simple, active, declarative sentences. It would appear that the response latency to negative statements is some function of grammatical structure. The matching task used in Miller's experiment, however, was designed to reflect only the syntactic level of language; the truth or falsity of the sentences was irrelevant to their identification. McMahon (1963) has shown that, when sentences of differing grammatical complexity have to be evaluated as true or false, the results are consistent in general with a theory of transformations, with three exceptions concerning negatives. (1) The evaluation time for negative sentences was considerably longer than that for passive sentences. This result has been corroborated by Slobin with children as Ss (Slobin, 1963).
8
WASON
(2) Sentences containing the preverbs "always" and "never" (e.g., "13 always follows 5," "5 never follows 13") differed significantly in evaluation time in spite of the fact that no negative transformation of a syntactical kind is involved. (3) When a delay was introduced between the presentation of a sentence and the stimulus necessary to evaluate it, the time taken to store the sentence, which was self-paced by the Ss, reflected the syntactical transformations involved. Only the negative transformation, however, and not the passive one, affected the time taken to evaluate the sentence as true or false. These exceptions indicate that, at the semantic level of truth and falsity, negation exercises additional effects. I n the present experiment two related but independent hypotheses about the objective contexts of plausible denial are postulated: the exceptionality hypothesis and the ratio hypothesis. The exceptionality hypothesis is as follows: Given a set of similar stimuli, xl, x2 . • • Xn, and a stimulus, y, which is perceived to differ from these in one important attribute, it is more plausible to assert that y is not x than to assert that xi is not y. For example, the statement to a child, "a whale is not a fish," would usually be more illuminating than the statement, "a herring is not an animal." A whale might be wrongly classified as a fish, b u t a herring would hardly be classified as an animal. Similarly, the statement, "the train was not late this morning," would obviously be more pertinent when the train is normally late than when it it normally punctual. The ratio hypothesis is as follows: Given two sets of stimuli which differ considerably in magnitude, it is more plausible to deny that the smaller set possesses a property of the larger set than to deny the converse. For example, the two statements, "of the eight contributions, one is not in Class l " (said with reference to insurance contributions),
and "one quarter of this square'is not red," seem intrinsically plausible ways of describing two facts. On the other hand, negative reference to the larger set seems more strained: "of the eight contributions, seven are not in Class 1 , " "three quarters of this square is not red." I n discourse, of course, the contexts defined in these hypotheses frequently occur together. The tasks used were designed to separate them by varying the way in which the same series of abstract stimuli is described. METttOD
Design. The experimental conditions used to test both hypotheses were four types of statement, each associated with a stimulus consisting of similar items (seven circles in the same color) and a dissimilar item (one circle in a different color): (1) affirmative statements about the color of the dissimilar item (DA); (2) negative statements about the color of the dissimilar item (DN); (3) affirmative statements about the color of a similar item (or items) (SA); (4) negative statements about the color of a similar item (or items) (SN). These conditions were presented in a series of 24 trials to two groups: an Exceptionality group (to test the exceptionality hypothesis) and a Ratio group (to test the ratio hypothesis). In both groups it was predicted that the difference between the time taken to respond to negative and affirmative statements about the color of the dissimilar items would be less than the corresponding difference for statements about the similar items, i.e., (DN - - DA) < (SN - - SA). The serial order of the conditions was counterbalanced in accordance with a previous design (Wason, 1959), each type occurring once in a different order for each S in every block of four trials, making a total of six presentations of each condition. Tasks. Only two colors were used in the stimuli: blue and red. Hence every sfimtilus consisted of either seven red items and one blue, or seven blue items and one red. Each trial had three successive phases. Exceptionality group: (1) The stimulus, in which the items were numbered consecutively from one to eight, was exposed for 3 sec; (2) the Ss were instructed to describe the stimulus aloud in their own words so that it could be identified, e.g., "circle No. 4 is blue and the rest are red"; (3) one of the four types of statement, referring to a specific
CONTEXTS OF PLAUSIBLE DENIAL item in the stimulus was presented, with the predi~ cate omitted, e.g., "circle No. 7 is . . . ," "circle No. 4 i s not . . ." The Ss responded with the color (blue or red) affirmed, or denied, of the item mentioned. The response was timed. Ratio group: (1) The treatment was the same as that in the Exceptionality group, but the items were not numbered; (2) the Ss were instructed to state aloud the number of items in each color, e.g., "seven circles are red and one is blue"; (3) the treatment was the same as that in the exceptionality group, but the statements were as follows: "exactly one circle is . . . . ," "exactly one circle is not . . . ," "exactly seven circles are . . . ," "exactly seven circles are not . . . . " Subjects. The Ss, 48 paid volunteers (35 women and 13 men), were students attending a summer school at Harvard University. They were assigned alternately to the groups and tested individually. Material. Twenty-four sets of stimuli were made for each group, the dissimilar item in each set appearing as red and as blue twice in each of the possible positions in the stimulus array except the first and eighth. The eight items were 0.2~ inch in diameter and were pasted on cards 6 X 4 inches in length in two rows of four. They were presented to a quarter of the Ss in a randomly determined order; to a quarter in the reverse of this order; to a quarter in the original order with colors interchanged; and to a quarter in the reverse Of this order. In the Exceptionality group 24 statements (each typed on cards 6 )< 4 inches in length) were matched with the 24 stimuli under the following constraints: (1) each of the four types of statement referred once to an item in each of the possible positions in the array except the first and eighth; (2) the correct response was blue on half the trials in every block of four and red on the other half. Only the latter constraint applied in the Ratio group where the four standard statements were each repeated six times. Procedure. At each trial the material was placed on a moving belt behind an apparatus. By depressing a switch /~ brought the stimulus into line with an aperture in front of the S; a second switch was then depressed to illuminate the stimulus and start a timer. After 3 sec. a third switch w a s depressed which removed the stimulus, stopped the timer,
9
and brought the statement into line with the aperture. The S's description of the stimulus was recorded by a second E and the timer was reset. The second switch was then depressed again to expose the statement and start the timer. The S responded by pressing either a key marked red, or a key marked blue (on the left and right of the apparatus, respectively), which stopped ' the timer and removed the statement. A pilot light informed R of the response. The time, to the nearest 0.01 sec, was recorded, t~)gether with the response. The material for the next trial was then loaded, that from the previous. one having been automatically ejected. The Ss were instructed in the sequence of events and were shown examp!es of the stimuli and statements. They were told they would be timed but were warned not to sacrifice accuracy for speed. Finally, they were trained in giving the responses by pressing the keys in answer to a random sequence of the words "blue" and "red" spoken by E. RESULTS
The Hypotheses. T h e m e a n r e s p o n s e t i m e to e a c h
c o n d i t i o n was
computed
for e a c h
S ( N --- 6). T a b l e 1 gives t h e m e a n of t h e s e values for b o t h g r o u p s ( N ~
24), t o g e t h e r
w i t h t h e m e a n n u m b e r of errors ( N z The prediction, (DN --DA)
<
144).
(SN -- SA),
was t e s t e d b y c a l c u l a t i n g t h e i n t e r a c t i o n Q, where
Q ~-~ ( S N - - S A )
-- (DN--DA),
for
e a c h S. T h e d i s t r i b u t i o n of Q was n o r m a l in the Exceptionality group and approximately n o r m a l in t h e R a t i o g r o u p . Scores a s s o c i a t e d w i t h errors w e r e n o t r e j e c t e d f r o m t h e c o m p u t a t i o n . W i t h o u t e r r o r s the m e a n s of t h e c o n d i t i o n s d e c r e a s e d on a v e r a g e b y 0.0.2 sec in t h e E x c e p t i o n a l i t y g r o u p a n d b y 0.06 sec in t h e
Ratio
group.
In
the Exceptionality
g r o u p Q - - + 0 . 2 5 sec ( r e l a t e d m e a n t - - 2.59, p < .01, o n e - t a i l e d ) ; in the R a t i o g r o u p Q - - - 0 . 1 6 sec (1'elated m e a n t ~
1.01, n o t sig-
n i f i c a n t ) . H e n c e , on t h e a s s u m p t i o n t h a t t h e effects o f t h e c o m p o n e n t s of t h e c o n d i t i o n s
TABLE 1 MEAN lk~SPONS~ TI~ES (SEC) AND MEAN NUMBER OF ERRORS Ratio group
Exceptionality group
Resp. time Errors
DA
DN
SA
SN
DA
DN
SA
SN
1.60 0.05
1.96 0.08
1.93 0.03
2.53 0.11
1.60 0.08
2.51 0.08
1.68 0.08
2.44 0.08
I0
WASON
are additive, the exceptionality hypothesis is .01) between the values of (DN - - DA) confirmed and the ratio hypothesis is not in the two groups. Inspection of Table 1 shows confirmed. On the alternative assumption that this result is entirely due to the difference that the effects of the components are multi- in response times to DN (1.96 sec in the plicative rather than additive, the individual Exceptionality group and 2.51 sec in the observations were converted into log trans- Ratio group), the response times to DA being forms. The same results were obtained with the same (1.60 sec). these transformed scores, b u t t h e exceptionThe DN statements have the same denotaality hypothesis was confirmed at only the tion in both groups, but they differ in the 0.025 confidence level. way in which the negated property, which Comparison between Groups. The mean is given as the response, has been coded in value of (DN - - DA) in the Ratio group the initial description of the stimulus. Con(+0.91 sec) was significantly greater than sider a stimulus in which the dissimilar item the corresponding value in the Exceptionality is blue and the similar items are red. In the group ( + 0 . 3 6 sec) (t -7- 3.49, p < .01), Exceptionality group the property negated in but the mean values of (SN - - SA) did not the statement would have been initially differ significantly. ( T h e same results were affirmed of a residual class which does not exist independently of the dissimilar item: obtained on the log transforms.) Initial Descriptions. In the Exceptionality "the rest are red." But the dissimilar item group 19 Ss consistently coded the stimuli in would, of course, cease to be an exception terms of an exceptional item followed by a without this residual class. The dissimilar residual class, e.g., ~'-'circle No. 4 is blue and item is the dominant feature and the residual the rest are red." Three Ss consistently men- class in the subsidiary feature, but the two tioned the exception last, e.g., "all the circles are reciprocally related. On analogy with are red except for No. 4 which is blue," perceptual phenomena, the dissimilar item and two Ss oscillated between the two kinds is the figure and the residual class is the of coding. In the Ratio group 16 Ss consist- ground against which the figure is coded as ently mentionbd the dissimilar item last, e.g., ari exception. In the Ratio group, on the "seven circles are red and one is blue," six other hand, the dissimilar item is negated consistently inverted this order, and two were in terms of a property which would have inconsistent. In both groups the mean re- • been initially affirmed of a discrete class which sponse times of the Ss, who consistently men- does have an independent existence: "seven tioned the dissimilar item last, were less on circles are red." These differences between the groups in all four conditions than the mean of those who consistently mentioned it first. The num- the initial coding suggest that the ease or bers are, of course, t~oo small to determine difficulty involved in denying a property of whether this result is a function of the order a class is a function o,f the formal characin which the items were described. It is clear, teristics of the contrast class of which the however, that this variable has no differential property is, explicitly or implicitly, predicated. The more this contrast class is pereffects on the response to the conditions. ceived, o r coded as subsidiary to the class DISCUSSION of interest, the more readily can its property The result which gives some insight into be abstracted and negated with respect to the confirmation of the exceptionality hypoth- the class of interest. The relevant variables esis and the nonconfirmation of the ratio cannot be more accurately defined until further -work has been done. The problem, in hypothesis is the tmpredicted difference (p <
CONTEXTS
OF P L A U S I B L E D E N I A L
general, is to isolate the distinctive features of descriptions which predispose a person to assent to a negative statement. The present investigation has shown that contextual variables associated with the concept of exceptionality affect the response to negation, in addition to the syntactic and semantic variables identified by Miller and his associates. I t is a task for the future to determine the contextual parameters which interact with the response to other grammatical categories. SUMMARY Two hypotheses were tested about the contexts which facilitate response to negative statements. The same" series of stimuli, each stimulus consisting of seven similar items and one dissimilar item, was described by two independent groups in differing terms. The dependent variable was the time taken to complete a statement presented immediately after each stimulus had been described. When the stimuli are described in terms of an exceptional item and a residual class, the response to negative statements is facilitated, if these statements deny that the exceptional item possesses the property of the residual class.
11
On the other hand, when the stimuli are described in terms of a smaller and a larger class, no facilitation of response to the corresponding negative statements is observed. I t is hypothesized that the determining factor in these results is the way in which the negated property is coded in the descriptions of the stimuli. REFERENCES
CHOIVISKY~ N. Syntactic structures. The Hague: Moulton & Co., 1957. MCMAHON, L. E. Grammatical analysis as part of understanding a sentence. Unpublished doctoral dissertation, Harvard University, 1963. MILLER, G. A. Some psychological studies of grammar. Amer. Psychologist, 1962, 17, 748-762. SLOBIN, D. I. Some psychological aspects of grammatical transformations in childhood and adulthood. Unpublished doctoral dissertation, Harvard University, 1963. WAsoI% P. C. The processing of positive and negative information. Quart. ]. exp. Psychol., 1959, 11, 92-107. WASON, P. C. Response to affirmative and negative binary statements. Brit. ]. Psychol., 1961, 52, 133-142. WASON, P. C., AND JON~S, S. Negatives: denotation and connotation. Brit. ]. Psychol., 1963, 54, 299307. (Received January 28, 1964)