N400 to Semantically Anomalous Pictures and Words

Arti Nigam, James E. Hoffian, and Robert F. Simons University of Delaware

Abstract Downloaded from http://mitprc.silverchair.com/jocn/article-pdf/4/1/15/1754910/jocn.1992.4.1.15.pdf by guest on 18 May 2021 The N400 component of the human event-related in one condition by a line drawing representing the same potential appears to be related to violations of semantic expec- concept (eg, the word “socks” was replaced by a picture of tancy during language comprehension.The present experiment socks). The N400 recorded in the Pictures Condition was found investigated whether the N400 is related specifically to activity to be identical to the N400 generated by words in terms of in a language system or is an index of a conceptual system that amplitude, scalp distribution, and latency. These results suggest is accessed by both pictures and words. Sentences were visually that the N400 is an index of activity in a conceptual presented one word at a time with the last word being replaced that is accessed by both pictures and words.

INTRODUCTION 1985a) rather than in a sentence context. The principal finding is that pairs of unrelated words or words that do In a seminal study, Kutas and Hillyard (1980) discovered not fit into the category established by the other words a component of the human event-related brain potential in the series elicit N400s. This is presumably due to (ERP) that appeared to be uniquely associated with lan- by semantically related words and words be- guage processing. Their subjects read sentences in which longing to a common category. the last word was occasionally anomalous, for example: Although these results are consistent with the claim “He likes cream and sugar in his socks.” The anomalous that N400 is inversely related to activation of word-level word elicited a negative component (the N400) with a nodes in a mental lexicon, they do not address the issue peak latency of approximately 400 msec and a maximum of whether N400 is specific to the language system. Per- amplitude at centroparietal scalp locations. Some studies haps N400 is a manifestation of a mismatch detection have shown a small right-greater-than-left hemispheric process that is common to a variety of tasks, not just asymmetry (Kutas & Hillyard, 1982), although this finding those involving language. Indeed, several investigators is not always reliable (Bentin, McCarthy, &Wood, 1985). have reported negative deflections to physical mis- Subsequent work showed that N400 was better de- matches in several sensory modalities, e.g., in audition scribed in terms of “cloze probability” rather than se- (Naatanen, 1985) and vision (Ritter, Simpson, &Vaughn, mantic anomaly (Kutas & Hillyard, 1980, 1984a). Thus, 1983). However, studies that have directly compared a semantically acceptable endings that are unexpected variety of linguistic and nonlinguistic tasks within the (e.g., “He likes cream and sugar in his tea.”) elicit an same experiment tend to support the claim that N400 is N400. These findings suggest that N400 amplitude may elicited only in language tasks. be inversely related to the degree of activation .of word Polich (1985b) compared ERPs to expectancy devia- nodes in a mental lexicon. This activation model predicts tions in four different contexts: (1) sentences, (2) se- that all words in a sentence should be associated with mantically related word series, (3) numeric series in an N400, with amplitude decreasing across word posi- simple arithmetic progression, and (4) alphabet series in tions as the increasing contextual constraints provide a similar progression. In this experiment, N400 was elic- greater degrees of “top-down’’activation. This prediction ited by expectancy deviations only in the sentences con- has been confirmed in several papers (Kutas, Van Petten, dition. In every other condition, ERPs to deviant-ending & Besson, 1988; Van Petten & Kutas, 1990, 1991). trials were relatively more positive than ERPs to normal- Additional support for the activation model comes ending trials. Besson and Macar (1987) obtained similar from studies in which words are presented in pairs results; they compared ERF’s to expectancy deviations in (Stuss, Picton, & Cerri, 1988; Kutas & Hillyard, 1989) or four contexts: (1) sentences, (2) familiar melodic tunes, series (Harbin, Marsh, & Harvey, 1984; Fischler, Bloom, (3) ascending or descending melodic scales, and (4) Childers, Roucos, & Perry, 1983; Rugg, 1985; Polich, geometric shapes systematically changing in size. A mis-

0 192 Massachusetts Institute of Technology Journal of Cognitive Neuroscience Volume 4, Number 1

Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/jocn.1992.4.1.15 by guest on 27 September 2021 match was constructed in melodic tunes by replacing the language system, and a clear test of this hypothesis would last note by a wrong note. In melodic scales, which went be to determine if an N400 is elicited by the conceptual either up or down, and in geometric shapes, which be- processing of pictures. Kutas and Hillyard (1984b) ex- came either larger or smaller within a given trial, mis- amined anomalous ending sentences in which the last matches were made by replacing the last element with word was replaced by a complex, unrecognizable draw- one that did not follow the sequence. As in Polich’s ing. These endings elicited a negative component that experiment (1985b), only unexpected words in the sen- was quite different in latency and scalp distribution from tences condition elicited a readily identifiable N400. Un- the N400 found with all-word anomalous sentences. Sim- expected endings in the tunes, scales, and shapes ilarly, Stuss, Picton, and Cerri (1986) found that unex- conditions elicited a , with no evidence of N400. pected pictures in a picture-naming task produced an In evaluating the hypothesis that N400 is uniquely N417 component with a markedly different scalp distri- related to language, it is useful to make a distinction bution than that associated with the N400. Although these between the mental lexicon, which is responsible for results suggest that the negative components elicited by storing knowledge about words, and an amodal system words and pictures are different, it should be noted that Downloaded from http://mitprc.silverchair.com/jocn/article-pdf/4/1/15/1754910/jocn.1992.4.1.15.pdf by guest on 18 May 2021 that represents conceptual knowledge independent of the abstract drawings used by Kutas and Hillyard would input modality (Potter, Kroll, Yachzel, Carpenter, & Sher- not be expected to have representations in a conceptual man, 1986; Theios & Amrhein, 1989). Clearly, language system. It is also unclear whether the naming task used is only one of several surface forms that are available for by Stuss et al. would require access to the conceptual conveying a concept. For example, both pictures and system. written words are visual symbols that may access a com- Similar comments apply to an experiment reported by mon, underlying conceptual system. Potter, Kroll, and Barrett, Rugg, and Perrett (1988) that compared EWs to colleagues have reported several findings in support of matching and nonmatching pairs of photographs of hu- this claim. For example, Potter et al. (1986) presented man faces. Subjects were presented sequentially with sentences to subjects using rapid serial visual presenta- pairs of photographs of famous and unfamiliar people; tion (RSVP) in which a noun was sometimes replaced by on half the trials, the two photographs were identical, a corresponding picture. Speed and accuracy of compre- and on half, they were different. In the famous people hension was comparable for all-word sentences and condition, mismatching faces produced negativity with a those containing a picture (REBUS sentences). In con- latency and scalp distribution similar to the N400. How- trast, naming a picture was about 200 msec slower than ever, for unfamiliar faces, there was no significant differ- naming a word suggesting that performance on REBUS ence in ERPs elicited by matches and mismatches. The sentences was not being mediated by covert naming of difference between the EWs elicited by famous and un- the picture. familiar faces is consistent with the idea that famous faces Additional support for the distinction between surface may have representations in an amodal conceptual sys- form systems and an amodal conceptual system is pro- tem. However, there is also the possibility that subjects vided by 0011 and Potter (1984). They compared a lexical used names to mediate performance in the famous peo- decision task with words and pseudowords to an object ple condition and the resulting N400 could be attributed decision task using drawings of objects and pseudo- to this covert naming. objects. Reaction time in each of these tasks was quite The present study was designed to directly compare similar suggesting the operation of a common conceptual pictures and words in terms of their ability to elicit the system. In contrast, when subjects performed in a com- N400 component. The principal theoretical question is bined version of these tasks in which the surface form whether the cognitive process indexed by the N400 com- of the items was unpredictable, there was a marked ponent reflects activity in a form-specific linguistic system elevation of reaction times, suggesting the presence of or an amodal, conceptual system that supports compre- form-specific systems as well. hension of both words and pictures. This hypothesis was More direct evidence for an amodal conceptual system tested using two kinds of sentences: all-word sentences mediating the comprehension of both words and pic- and sentences in which the last word was replaced by a tures was presented by Kroll and Venugopal(1984). They picture representing the same concept (see Fig. 1). Sim- found that an object decision about a picture was ilar N400s in the two conditions would provide evidence speeded by a preceding linguistic context that was com- favoring the position that the N400 is an index of con- patible with the pictured object. Facilitation of processing ceptual processing. of one surface form produced by presentation of se- The possibility that performance in the pictures con- mantically related information in a different surface form dition is mediated by covert naming can be evaluated by is the strongest evidence of a common underlying con- examining the latency of the N400 in the two conditions. ceptual system. Several investigators have found that naming of pictures These results raise the possibility that N400 is an index is some 150-200 msec slower than word naming (Potter of activity in the conceptual system rather than a specific et al., 1986; Theios & Amrhein, 1989). Theios and Amr-

IG Journal of Cognitive Neuroscience Volume 4, Number 1

Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/jocn.1992.4.1.15 by guest on 27 September 2021 Despite the overall difference between the words and Normal Sentence Type: pictures conditions, a substantial N400 component was a prominent feature of the ERP associated with the anom- I can never find a matching pair of alous sentences in both conditions. A comparison of N400-range amplitude for the two Sentence Types shows Anomalous Sentence Type: that anomalous sentences were associated with signifi- cantly greater negativity than were normal sentences I ate an apple and am [F(1,25) = 45.82,~< 0.00011. N400 achieved its maxi- mum amplitude in the centroparietal region. The analysis of variance showed a main effect of Electrode Site Figure 1. An example of a Normal and Anomalous sentence in the [F(4,100) = 5.94, p < 0.0003], with amplitude smaller at Pictures Condition. Note that this diagram is not to scale and in the Oz than at other sites. The effect of Site was specific to experiment, pictures and words were approximately the same size. the Anomalous Sentence Type. In addition, a significant Sentence Type X Electrode Site interaction [F(4,100) = Downloaded from http://mitprc.silverchair.com/jocn/article-pdf/4/1/15/1754910/jocn.1992.4.1.15.pdf by guest on 18 May 2021 6.15, p < 0.0003]indicates that the scalp distribution of hein (1989) showed that this difference is due to two N400 differs for normal and anomalous sentence types. processes occurring in picture naming that do not occur Figure 3 shows the difference waveforms at the five in word naming. First, a word can be named without Electrode Sites, averaged across subjects within the access to meaning, presumably through a grapheme-to- Words and Pictures Conditions. In the difference wave- phoneme conversion system, whereas pictures require forms, N400 is apparent at all five Sites. As with the semantic access to retrieve a label. Second, a word gen- averaged waveforms, N400 had the smallest amplitude at erally produces a single name while a picture may pro- Oz [main effect of Site: F(4,lOO) = 11.44,p < O.OOOl]. duce several possible labels, leading to further delays as N400 amplitude is essentially the same in both Words the set of alternatives is winnowed down to the one and Pictures Conditions [main effect of Condition: “correct” name required by the experimenter. Further, F(1,25) = l.00,p > 0.321. they showed that in a task that only required access to Planned comparisons of N400 amplitude at the left and meaning rather than verbal labels, pictures and words right Electrode Sites showed no significant difference were equally fast. The present task can clearly be per- either in the Pictures Condition [t(ll) = 1.489,p > 0.101 formed by ignoring the modality (pictures vs. words) of or in the Words Condition [t(13) = -1.19,p > 0.101. the input and using meaning codes. Therefore, if the Since 4 out of 12 subjects in the Pictures Condition were N400 reflects activity in an amodal conceptual system, left handed, hemispheric asymmetry was also assessed we should find similar N400s for both picture and word separately for right-handed subjects alone and for left- endings. On the other hand, if N400 indexes activity in handed subjects alone. A comparison of the averaged a linguistic system and subjects are covertly naming the and difference waveforms of left-handed and right- pictures, we should find that the latency of the N400 in handed subjects in the Pictures Condition shows no dif- the picture condition is delayed 150-200 msec relative ference with respect to asymmetry; neither group to the word condition, showed a difference in N400 amplitude between the left and right hemispheres. RESULTS Regarding N400 peak latency, there were no significant differences between Words and Pictures Conditions. N400 There were no effects of Condition [F(1,25) < 11, and Figure 2 shows the grand averaged waveforms at the five no Site x Condition interaction effect [F(4,100) = 1.41, Electrode Sites for Words and Pictures Conditions, and p > 0.23511 on N400 latency. for Normal and Anomalous Sentences. In the N400 la- tency range, amplitude was more negative in the Words Condition than in the Pictures Condition [Condition main effect F(1,25) = 4.47, 0.051. In fact, ERP waveforms p < Early Sensory Components to Words were more negative overall, compared to ERP waveforms to Pictures, after the first 200 msec. An analysis In the present study, a series of early visual components of variance conducted on the mean amplitude of wave- is observed in the grand average waveform from Oz (see forms in the 200 to 900 msec latency range showed the Fig. 2); this is consistent with findings in a variety of effect of Condition to be significant [F(1,24)= 6.56,~< studies using visual stimuli (see, for example, Mangun & 0.021. This negativity seems to be unrelated to the N400 Hillyard, 1987). The series observed here was P100, component since it is independent of Sentence Type, N180, P210, N235. Although there is a suggestion of a such that both normal and anomalous sentences pro- larger PlOO amplitude for pictures than words, it did not duced more negativity in the Words Condition. reach significance [t(24) = 1.97,~< 0.101.

Nigum et ul. 17

Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/jocn.1992.4.1.15 by guest on 27 September 2021 Figure 2. Grand average ERP waveforms for five recording sites as a function of condition (Picture vs. Word) and sen- tence type (Normal vs. Anoma- lous ending).

Left Right -4 -4

-2 -2 Downloaded from http://mitprc.silverchair.com/jocn/article-pdf/4/1/15/1754910/jocn.1992.4.1.15.pdf by guest on 18 May 2021 0 0 2 2

4 4 6 6

8 6 0 200 4w 600 8000 200 400 600 Mx) Latry (rmlllrsondr)

-----NormplWo& -.... NormaIPeturs -Anom Words -Anom Pictures

Figure 3. Difference ERP waveforms constructed by sub- tracting the normal sentence ERP from the anomalous sen- .3 -3 tence EW. Data are shown for -2 -2 five recording sites as a func- -1 -1 tion of condition (Picture vs. 0 0 Word). 1 1 2 2 3 3 0 2w 400 Mo 8000 2w m Mo 8000 2w m Mo 800

Left Right -4 -3 -3 -2 -2 -1 -1

0 0 1 1 2 2

DISCUSSION were found between the N400 elicited by all-word sen- The present experiment compared the N400 component tences and the N400 elicited by picture-ending sentences, of the event-related brain potential (ERP) produced by either in amplitude, latency, or scalp distribution. The the conceptual processing of words and pictures. Sen- similarity in N400 latency across Conditions seems to tences that ended in anomalous words or pictures pro- rule out the possibility that the name of each picture was duced a clear N400 component that was absent in accessed prior to evoking the N400; if this were the case, sentences with normal endings. This component was the N400 to pictures would occur later than the N400 to similar to that reported by Kutas and Hillyard (for ex- words. These findings show that the N400 component is ample, 1980, 1982), with respect to its amplitude, onset not uniquely tied to the surface properties of a language and peak latency, and scalp distribution. No differences module but instead reflects activity in a system that is

18 Journal of Cognitive Neuroscience Volume 4, Number 1

Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/jocn.1992.4.1.15 by guest on 27 September 2021 common to both pictures and words. By similar argu- etal sites. It seems possible that this anterior negativity ment, the N400 is also not specifically tied to an imaginal has a different origin and identity from the N400 com- code or system. Rather, the findings of this study are ponent, which appears to require meaningful stimuli in consistent with the hypothesis of a shared, amodal con- a semantic context. ceptual system. Two studies by Rugg (1984a, b) stand out as somewhat How well does the conceptual hypothesis fare in ac- anomalous in the N400 literature. Rugg (1984a) used counting for those tasks that do and do not produce pairs of words in which the relationship between the N400s? Recall that neither number series (Polich, 1985b) pair was acoustic rather than semantic; subjects had to nor melodies (Besson & Macar, 1987) are associated report whether the two words rhymed with each other with an N400, which would suggest that concepts in these or not. Pairs were semantically unrelated. Rugg reported domains reside in a representation system that is distinct finding an N400-like component in the ERF’s to nonrhym- from that underlying pictures and words. Although this ing pairs, compared to the ERF’s to rhyming pairs. In inference is somewhat post hoc, there is some support- addition to being in the N400 latency range, this com- ing evidence to be found in the neuropsychological lit- ponent resembled the N400 of the present study with Downloaded from http://mitprc.silverchair.com/jocn/article-pdf/4/1/15/1754910/jocn.1992.4.1.15.pdf by guest on 18 May 2021 erature. Acalculia refers to a selective deficit in the ability respect to scalp distribution as well. Rugg (1984b) was to comprehend numbers or perform calculations even able to replicate the finding using word pairs in which though language comprehension remains intact (Mc- the second word was a pseudoword, thus decreasing the Carthy & Warrington, 1990). Similarly, amusia may in- likelihood that some kind of automatically engaged se- clude “melody deafness,” which is an impaired recall or mantic analysis process was responsible for the N400. It recognition of familiar melodies (Kolb & Whishaw, is unclear what is common between the task in Rugg’s 1990). There is at least some evidence that this deficit studies and the semantic tasks that have been shown to may coexist with normal function in other cognitive do- elicit N400. mains such as language. The finding that N400 is obtained for some kinds of semantic knowledge and not others raises the possibility that this component could be a CONCLUSION useful tool in discovering the structure of conceptual Our finding of similar N400s elicited by words and pic- knowledge. tures is consistent with several other findings in the N400 The conceptual hypothesis is also consistent with those literature. It has been found that similar N400s are elic- studies that have found negative components that appear ited by linguistic materials presented in a variety of for- to be different in scalp distribution from the prototypical mats ranging from visual (Kutas & Hillyard, 1980) and N400. For example, Kutas and Hillyard’s study using sen- auditory words (McCallum, Farmer, & Pocock, 1984) to tences that ended in anomalous pictures (1984b) elicited American Sign Language (Kutas, Neville, & Holcomb, a component that was different from the N400 reported 1987). The present results extend these findings to non- here and in Kutas and Hillyard’s earlier studies (e.g., verbal, pictorial materials and clearly implicate an amo- 1982). Anomalous pictures in Kutas and Hillyard’s dal, abstract semantic system as the representation (1984b) study evoked a negative ERF’ component with an indexed by the N400. earlier latency (320 msec) and different scalp distribution (absent at the parietal site), compared to the N400 evoked by all-word anomalous sentences. The notable METHOD difference between the design of their study and the Subjects present one is our use of pictures that were meaningful (i.e., each picture was a readily interpretable, concrete Twentysix undergraduates (1 1 female, 15 male, ranging representation of a known object or concept); Kutas and in age from 17 to 21 years) were selected from the pool Hillyard (1984b) had used abstract line drawings as of students in an introductory psychology course. Sub- anomalous stimuli; these pictures were nonrepresenta- jects received credit for participation, and were also paid tional or difficult to interpret. $5.00 per hour for time spent beyond the first hour. Similarly, the negative components elicited by Stuss Fourteen subjects were assigned to the Words Condition, et al. (1986) to low-frequency pictures, by Neville et al. and 12 were assigned to the Pictures Condition. Subjects (1982) to simple word naming, and by Stuss et al. (1983) were screened for handedness and native language. to word naming, picture naming, and geometric shape Three female subjects and one male subject in the Pic- comparisons, all show a scalp distribution similar to that tures Condition were left-handed. Subjects were ex- obtained by Kutas and Hillyard (1984b) to meaningless cluded for whom English was a second language. pictures. In Stuss et al. (1986), an expectancy was created solely by repetition. In the Neville et al. (1982) and Stuss Stimulus Material et al. (1983) studies, no expectancy or priming was cre- ated at all. In each case, the component was larger over Sentences were used to provide a context, since the anterior electrode sites, being smallest or absent at pari- clearest and prototypic N400 has been elicited using the

Nigum et ul. 19

Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/jocn.1992.4.1.15 by guest on 27 September 2021 anomalous-ending sentence paradigm. Forty percent of was in the homologous position on the right side, to the sentences ended in a semantically incongruous word, serve as a comparison. Each active electrode was referred and 60% ended in an expected word. The ending word to a linked mastoid reference. Eye blinks were monitored of each sentence was presented either in a linguistic using electrodes placed directly above the left brow and format (Words Condition) or in a picture format (Pictures on the left lower orbital ridge. Horizontal eye movement Condition). was monitored using electrodes placed at the outer can- The stimuli for the Words Condition consisted of 120 thi of the right and left eyes. normal-ending sentences and 80 anomalous-ending sen- EEG and electro-oculogram (EOG) were recorded tences. Each item was a simple, subject-predicate sen- with miniature surface Ag-AgC1 electrodes. The skin was tence, 6 to 12 words in length, and each sentence ended abraded at each electrode site, and electrodes were fixed in a concrete noun that was the object of the verb. Stimuli in place by Grass EC-2 electrode cream or electrode for the Pictures Condition consisted of the same 200 collars when necessary. Electrode impedance was kept items except that the last word of each sentence was below 5 k0 for scalp electrodes and below 10 k0 for replaced by a line-drawing that was representative of the EOG electrodes. EEG was processed through Coulbourn Downloaded from http://mitprc.silverchair.com/jocn/article-pdf/4/1/15/1754910/jocn.1992.4.1.15.pdf by guest on 18 May 2021 word. These line drawings were taken from a standard- Model S75-01 High-gain bioamplifiers (gain = 20k; band- ized set of pictures published by Snodgrass and Vander- pass = 0.1-40 Hz). EOG was processed through Coul- wart (1980). Pilot testing established that the sentences bourn Model S75-07 direct-coupled bioamplifiers (gain classified as Normal Sentences had very expected end- = 5K low-pass filter cutoff = 41.2 Hz). ings, and those classified as Anomalous Sentences had EEG and EOG were digitized every 5 msec by the IBM- very unexpected endings. The familiarity of pictures used PC/AT computer beginning 100 msec before the onset of in normal sentences was comparable to that of pictures each target stimulus and continuing for 1000 msec. The used in anomalous sentences. single-trial EEG data were corrected off-line for both vertical and horizontal eye movement artifact using the regression technique described by Gratton, Coles, and Stimulus Display Donchin (1783). Ten averaged waveforms were then Stimuli were displayed on a Mitsubishi XC color display computed for each subject (five Electrode Sites and two monitor, using a Matrox PG640A graphics processor con- Sentence Types). trolled by an IBM-PC/AT. The room was kept dark during stimulus presentation. Sentences were displayed one word or picture at a time (100 msec duration) with a Procedure 600 msec interword interval. Each sentence was followed by the pattern ‘‘XGZX,”displayed in the center of the Each subject was tested in a single session lasting ap- screen for 1000 msec, indicating the start of the next proximately 80 mins. Subjects were informed that they trial. There was a 600 msec delay preceding and follow- were participating in an experiment on language com- ing this intertrial marker. All stimuli were presented at prehension and associated brain activity. They were told the center of the screen, in black, within a 4 cm high that they would read a series of sentences displayed on and 22 cm wide white rectangle. The screen outside the the screen, and at the end of all the sentences, they would rectangle was black. A low luminance was used for the complete a questionnaire about the sentences they saw. stimulus background to reduce eye strain. Subjects Electrodes were attached, and’subjectswere presented viewed the screen from a distance of approximately 55 with four demonstration sentences, three of which were cm; all stimuli subtended a vertical angle of approxi- normal-ending and one of which was anomalous-ending. mately 4” with horizontal angles ranging from 3” to 15”. Subjects were told that some times the sentences would make sense, and some times they would not, but their task was just to read each sentence. Subjects were asked Recording System to try to minimize blinking during a trial; they were told Electroencephalogram (EEG) activity was recorded from to try to wait for the intertrial marker, “XxxXX,”to come five scalp electrodes, referred to linked mastoid. Three on the screen, before blinking, so as to minimize eye electrodes were placed according to the International movement artifact. The room was then darkened, and 10-20 convention (Harner & Sannit, 1974) at Cz, Pz, and subjects started the stimulus presentation by pressing a Oz, located on the midline of the scalp over central, button. After each set of 10 sentences, there was a rest parietal, and occipital cortical areas respectively. Sym- period, marked by instructions displayed on the screen. metric temporoparietal electrodes were placed over the The instructions told subjects to restart the display by left and right hemispheres, laterally (by 30% of interaural pressing the button again when they were ready to con- distance) and posterior (by 12.5% of the nasion-inion tinue. distance) to the vertex (Kutas & Hillyard, 1782, 1783). After all 200 sentences had been displayed, electrodes Over the left hemisphere, this electrode was located were removed and subjects were given a paper-and- approximately over Wernicke’s area. The right electrode pencil recognition task. This task was intended primarily

20 Journal of Cognitive Neuroscience Volume 4, Number 1

Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/jocn.1992.4.1.15 by guest on 27 September 2021 as a check of treatment integrity, that is, to verify that in the late components of the event-related potential due subjects attended to the stimuli. to age and to semantic and non-semantic tasks. Electroen- cephalography and Clinical Neurophysiology,59( 6), 489- 496. Harner, P. F., & Sannit, T. (1974). A review of the intewla- Data Analysis tional ten-twenty system of electrode placement. Quincy, Averaged ERP waveforms were computed after subtract- MA. Grass Instrument Company. Kolb, B., & Whishaw, I. Q. (1990). Fundamentak of human ing the prestimulus baseline. Peak analyses were con- neuropsychology. New York: Freeman. ducted by finding the maximum positive or negative Kroll, J. F., & Potter, M. C. (1984). Recognizing words, pic- deflection in particular temporal windows as follows: P1 tures, and concepts: A comparison of lexical, object, and (60-140 msec), N1 (110-190 msec), P2 (190-260 msec), reality decisions. Journal of Verbal Learning and Verbal N2 (230-300 msec), and N400 (270-420 msec). These Behavior, 23, 39-66. Kroll, J. F., & Venugopal, V. (1984). Lexical and object deci- amplitude values were subjected to a mixed model anal- sions in sentence context. Paper presented at the Meeting

ysis of variance (ANOVA) with two within-subject vari- of Psychonomic Society, San Antonio. Downloaded from http://mitprc.silverchair.com/jocn/article-pdf/4/1/15/1754910/jocn.1992.4.1.15.pdf by guest on 18 May 2021 ables (Electrode Site and Sentence Type), and one Kutas, M., & Hillyard, S. A. (1980). senseless sen- between-subjects variable (Condition: pictures or tences: Brain potentials reflect semantic incongruity. Sci- words). To isolate further the difference between the ence, 207(4427), 203-205. Kutas, M., & Hillyard, S. A. (1982). The lateral distribution of waveforms to normal and anomalous sentences, differ- event-related potentials during sentence processing. Neu- ence waveforms were computed for each subject by sub- ropsychologia, 20(5), 579-590. tracting the Normal Sentence Type waveform, point-by- Kutas, M., & Hillyard, S. A. (1983). Event-related brain poten- point, from the Anomalous Sentence Type waveform, for tials to grammatical errors and semantic anomalies. Mem- each Electrode Site. These difference waveforms have ory and Cognition, lI(5), 539-550. Kutas, M., & Hillyard, S. A. (1984a). Brain potentials during the advantage of excluding those factors that are common reading reflect word expectancy & semantic association. to the processing of both sentence types, thereby isolat- Nature (London),307(5954), 161-163. ing ERP effects that reflect the detection of the anomalous Kutas, M., & Hillyard, S. A. (198413). Event-related potentials ending. The N400 peak amplitude and latency in the (ERPs) elicited by novel stimuli during sentence process- ing. Sixth International Conference on Event-Related Slow difference waveforms were also analyzed, with a Site X Potentials of the Brain: Cognition, Information Processing, Condition ANOVA. and Language; 1981. Annals of the New York Academy of Sciences, 425, 236-241. Kutas, M., & Hillyard, S. A. (1989). An electrophysiological Acknowledgments probe of incidental semantic association. Journal of Cogni- tive Neuroscience, 1, 38-49. This research was supported by the Army Research Office un- Kutas, M., Neville, H. J., & Holcomb, P. J. (1987). A prelimi- der the contract DAALO3-86-K-0080 and was submitted by the nary comparison of the N400 response to semantic anom- first author in partial fulfillment of the requirements for a alies during reading, listening, and signing. In R. J. Masters degree. Portions of this paper were presented at the Ellingson, N. M. F. Murray, & A. M. Halliday (Eds.), 7be Lon- 30th Annual meeting of the Society for Psychophysiological don Symposia (pp. 325-330). Elsevier Science Publish- Research, Boston, MA, October 1990. NY: ers. Kutas, M., Van Petten, C., & Besson, M. (1988). Event-related Reprint requests should be sent to James E. Hoffman, Depart- potential asymmetries during the reading of sentences. ment of Psychology, University of Delaware, Newark, Delaware Electroencephalograpby and Clinical Neurophysiology, G9, 19716. 218-233. Mangun, G. R., & Hillyard, S. A. (1987). The spatial allocation of visual attention as indexed by event-related brain poten- REFERENCES tials. Human Factors, 29(2), 195-211. Barrett, S. E., Rugg, M. D., & Perrett, D. I. (1988). Event-re- McCallum, W. C., Farmer, S. F. & Pocock, P. V. (1984). The lated potentials and the matching of familiar and unfamiliar effects of physical and semantic incongruities on auditory faces. Neuropsychologia,26(1), 105-1 17. event-related potentials. Electroencephalograpby and Clini- Bentin, S., McCarthy, G., & Wood, C. C. (1985). Event-related cal Neurophysiology, 59, 477-488. potentials, lexical decision, and semantic priming. Elec- McCarthy, R. A,, & Warrington, E. K. (1990). Cognitive neuro- troencephalography and Clinical Neuropbysiology, 60, psychology: A clinical introduction. San Diego: Academic 343-355. Press. Besson, M., & Macar, F. (1987). An event-related potential Naatanen, R. (1985). Stimulus processing: Reflections in event- analysis of incongruity in music and other non-linguistic related potentials, magnetoencephalogram, and regional contexts. Psychophysiology, 24, 14-25. cerebral blood flow. In M. I. Posner & 0. S. M. Marin Fischler, I., Bloom, P. A,, Childers, D. G., Roucos, S. E., & (Eds.), Mechanism of attention: Attention and pear- Perry, N. W., Jr. (1983). Brain potentials related to stages of mance XI (pp. 355-373). Hillsdale, NJ: Erlbaum. sentence verification. Psychophysiology, 20(4), 400-409. Neville, H. J., Kutas, M., & Schmidt, A. (1982). Event-related Gratton, G., Coles, M. G. H., & Donchin, E. (1983). A new potential studies of cerebral specialization during reading. method for off-line removal of ocular artifact. Electroenceph- Brain and Language, 16, 300-315. alography and Clinical Neurophysiology, 55, 468-484. Polich, J. (1985a). Semantic categorization and event-related Harbin, T. J., Marsh, G. R., & Harvey, M. T. (1984). Differences potentials. Brain and Language, 26( 2), 304-32 1.

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