the effect of accomplishment and failure on p300 potentials evoked by neutral stimuli

\PERGAMON Neuropsychologia 26 "0888# 302Ð319

9917Ð2821:88:,*see front matter Þ 0888 Elsevier Science Ltd[ All rights reservedPII] S 9 9 1 7 Ð 2 8 2 1 " 8 7 # 9 9 0 9 5 Ð 6

The e}ect of accomplishment and failure on P299 potentials evokedby neutral stimuli

Andrzej Michalski�Department of Neurophysiology\ Nencki Institute of Experimental Biology\ 2 Pasteur St\ 91!982 Warsaw\ Poland

Received 04 September 0886^ accepted 06 March 0887

Abstract

The e}ects of emotional states of {being successful| vs[ {being unsuccessful| were studied by measuring the P299 component ofevent!related potentials "ERPs#[ Nine subjects were instructed to reduce their P299 amplitude using feedback[ Feedback was randombut the relative probability of di}erent signals created the situations of {being successful| or {being unsuccessful|[ The probability of{small| feedback was 9[6 in {successful| and 9[04 in {unsuccessful| trials[ ERPs recorded without the feedback were used as a reference[Potentials\ evoked by light stimuli in a standard {odd!ball| procedure\ were recorded from Fz\ Cz and Pz scalp sites[ The amplitudesof P299 components were reduced in {unsuccessful| trials whereas in {successful| trials they did not di}er signi_cantly from responsesrecorded without the feedback[ There were no signi_cant di}erences in peak latencies[ These _ndings indicate that tonic emotionalstates a}ect the processing of neutral stimuli and that late components of ERPs can be useful indices in the analysis of thesealterations[ The results also indicate that the e}ects of positive and negative emotional states are not always reciprocal[ Manipulatedfeedback is suggested as an useful model in the studies of emotions[ Data can also facilitate the interpretation of the real feedbacke}ects[ Þ 0888 Elsevier Science Ltd[ All rights reserved[

Keywords] P299^ Success^ Failure

0[ Introduction

There have been numerous attempts to study the e}ectof emotions on the P299 potential[ In a number of experi!ments facial expressions have been used\ since these arestimuli considered to be phylogenetically specialized foremotional communication ð7Ł[ The results were con!tradictory[ In some studies the neutral faces evoked loweramplitudes than emotional ones ð0\ 1\ 19Ł^ in others theyevoked the highest responses ð23Ł[ Testing stimuli otherthan faces\ Radilova� and co!workers ð16Ð18Ł showed thaterotic stimuli produced more positive P299 waves thannon!erotic pictures[ Johnston and co!workers ð05Ð07Łshowed that both pictures of nude models of oppositesex and pictures of dermatological diseases evoked graterP299 amplitudes than neutral pictures[ This _nding wascon_rmed by Palomba and co!authors ð12\ 13Ł[ Apartfrom the di}erences in experimental methods\ oneelement of the procedure was common in all these studies]the same stimulus that evoked P299 potential also trig!gered the emotional response[

� Corresponding author[ Tel[] ¦37 11 548 74 60^ fax] ¦37 11 11 4231^ e!mail] michanÝnencki[gov[pl

To resolve the discrepancy between the results ofexperiments on hemispheric localization of emotions\Sobo�tka and co!authors ð21Ł suggested di}erent mech!anisms for the brief reactions to emotional stimuli and themore prolonged emotional states that a}ect processing ofthe neutral stimuli[ The analysis of available data ledthese authors\ in agreement with the hypothesis originallydeveloped by Gardner ð09Ł\ to conclude that patterns ofbrain functions associated with judgments of theemotional content of stimuli\ such as facial expressions\indicated the dominance of right hemisphere for bothpositive and negative emotions[ On the other hand\ thecharged emotional states associated with brain damageð8\ 29Ł\ injections of sodium amytal ð22Ł or watchingemotional _lms ð4Ł have been reported to produce pat!terns of activation that support an alternative hypothesisof Goldstein ð00Ł\ that the left hemisphere is dominantfor positive emotions and right hemisphere for negativeemotions[ Such di}erences suggest that event!relatedpotentials\ especially the late components\ may also bedi}erentially a}ected by prolonged emotional states andby brief responses to the emotional component of evok!ing stimuli[

The aim of the present experiment was to analyze thee}ects of tonic emotional states "being successful vs being

A[ Michalski:Neuropsycholo`ia 26 "0888# 302Ð319303

unsuccessful# on P299 component of the ERPs evokedby non!emotional stimuli "red and yellow ~ashes of light#[Since random feedback procedures were used to manipu!late the emotional states\ the results will also be relevantto the interpretation of the real feedback e}ects ð20Ł[

1[ Methods

1[0[ Subjects

Volunteers were informed that they were being askedto participate in standard feedback experiments and theirconsent was obtained[ Before the experiment\ each par!ticipant was asked to evaluate his:her level of anxiety andmood state using a ten!point scale[ The {normal| level ofanxiety and the {neutral| mood corresponded to value 4on the scale[ Data were collected from nine volunteers ofboth sexes "seven females and two males#\ aged 18Ð37years[ They were all familiar with the laboratory and theyall reported their anxiety level and mood state to rangebetween 3 and 5 on the scale[ Two additional participants"at the end of the series# expressed their concern that {theexperiment was strange|\ and they were excluded fromthe experiment[

1[1[ Recording

EEG signals were recorded with disc electrodes gluedat Fz\ Cz and Pz positions\ referenced to linked mastoidsand supplemented by vertical and horizontal EOG[ Sig!nals were sampled with 1937 Hz frequency\ 01 bit resol!ution\ digitally _ltered 9[05Ð29 Hz and reduced to 145Hz by averaging the adjacent points "Elmiko PaperlessEEG system#[ Data were stored in epochs containing 149ms before and 0 s after the stimulus onset[ Epochs wererejected by computer program if EOG amplitudeexceeded 39 mV[ Rejected epochs were replaced with thenew ones[

Flashes of spatially overlapped arrays of red and yel!low LED diodes "1> � 1> of the visual angle\ 09 cd:m1

luminosity on 0 cd:m1 background\ 099 ms duration#were used as stimuli in a standard odd!ball procedure"stimulus rate*1[4 s^ target probability*9[01^ minimumnumber of good target stimulus repetitions*29#[ Sub!jects were asked to mentally count the target stimuli andreport the number seen at the end of the recording[ Datawere rejected if the error in counting was bigger than19)[

1[2[ Procedures

To reduce the number of variables\ the yellow LEDdiode was always used as a target and the task instructionwas always to reduce the amplitude of P299 potentials"downtraining#[ Downtraining was selected because it

had produced bigger e}ects in an earlier experimentalattempt to use the real feedback paradigm "unpublisheddata from the same laboratory#[ Subjects were asked toreduce the P299 amplitude using feedback provided bythe spoken words {small|\ {medium| or {large|\ pro!nounced by the experimenter 0 s after the onset of eachtarget stimulus[ The words were taken from tables whichensured their random distribution\ regardless of theamplitude of real potentials[ In the {successful| trials theprobability of {small| was 9[6\ {medium|\ 9[04 and {large|\9[04[ In the {unsuccessful|\ trials the probability of {small|was 9[04\ {medium|\ 9[04 and {large|\ 9[6[ The exper!imental session always contained a sequence of _ve rec!ordings]

0[ recording without the feedback\1[ randomly selected {successful| or {unsuccessful| feed!

back recording\2[ recording without the feedback\3[ complementary {successful| or {unsuccessful| feedback

recording\4[ recording without the feedback[

1[3[ Data analysis

Epochs of EEG were averaged\ stored and printedusing Elmiko software package[ Di}erence curves werecomputed for each pair of target and non!target ERPs[Grand!averaged waveforms were computed by averagingdata for all subjects in each experimental condition[ Stat!istical analysis followed two basic strategies]

0[ Amplitudes and latencies of peaks were measuredusing cursors on the computer screen and the datawere transferred to SYSTAT program for multi!factoranalysis of variance "ANOVA#[

1[ Grand!averaged curves\ computed for each exper!imental condition\ were compared[ Within the regionsof visible di}erences the corresponding points ofgrand!averaged curves were expanded into sets ofpaired data "points of individual di}erence curves# andcompared with Student{s t!test[ Direct comparison ofthe curves avoided the arbitrary peak identi_cation\on the other hand\ it did not allow the {latency cor!rections| "the scatter of peak latencies could a}ect thegrand averaged waveshapes#[

2[ Results

The responses to target stimuli\ grand!averaged overall subjects\ are shown in Fig[ 0[ Three sets of curvesrepresent the data recorded from Fz "top#\ Cz "middle#and Pz "bottom# electrodes[ Dotted lines show the wav!eforms obtained without the feedback[ Dashed lines showthe potentials recorded with the dummy feedback thatcontained 69) of {small| messages[ Since the instruction

A[ Michalski:Neuropsycholo`ia 26 "0888# 302Ð319 304

Fig[ 0[ Grand!averaged ERPs evoked by target stimuli[ Potentials were recorded with Fz "top#\ Cz "middle# and Pz "bottom# electrodes[ Dotted linesshow the ERPs recorded without the feedback[ Dashed lines show the ERPs recorded with the feedback and the instruction to reduce the P299amplitude[ Feedback was random but it contained 69) of {small| signals[ The subjects were {successful|[ Solid lines show the ERPs recorded withthe feedback and the instruction to reduce the P299 amplitude[ Feedback was random but contained only 04) of {small| signals[ The subjects were{unsuccessful|[

was to reduce the P299 amplitude\ the subject was {suc!cessful|[ This situation will be referred to as a {positivecontext|[ Solid lines show the recordings obtained withthe dummy feedback that contained 04) of {small| mess!ages[ Since the instruction was still to reduce the P299

amplitude\ the subject was {unsuccessful|[ This situationwill be referred to as a {negative context|[

In addition to the early waves\ all the recordings showthe well developed late components within the P199 andP299 regions[ It is clear that the experimental procedures


a}ected the P299 waves much more than the earlier com!ponents[ Both types of feedback reduced the P299 ampli!tude but in the case of negative context the reduction wasgreater[

The P299 peak was de_ned as the positive value ofgreatest magnitude between 149 msÐ399 ms following thestimulus onset\ and the P199 peak was de_ned as thelargest positive value recorded between 049 msÐ189 msafter the stimulus onset[ Amplitudes\ measured in indi!vidual ERPs relative to 149 ms pre!stimulus baseline\were analyzed with two way ANOVA "electrode �context#[ Context variable included the positive context\negative context and no feedback condition[ Di}erences

Fig[ 1[ Grand!averaged ERPs evoked by non!target stimuli[ Figure conventions are the same as in Fig[ 0[

in both P299 and P199 peak amplitudes due to the contexttype were insigni_cant[ Latencies of both peaks\ analyzedwith the identical two way ANOVA\ also did not showany signi_cant e}ects of the context[

The grand!averaged potentials evoked by non!targetstimuli are illustrated in Fig[ 1 "_gure conventions arethe same as in Fig[ 0#[ Besides the early components\recordings from all electrodes showed well!developedP199 waves and only greatly reduced P299 components[The comparison of Figs 1 and 0 indicates that di}erences\due to the type of the context\ were much greater in thetarget responses[

In the individual non!target recordings\ the very small


size of the P299 components made it impossible to ident!ify and measure this component reliably[ Thus\ only P199waves were analyzed[ Two way ANOVA "electrode �context# showed that context type clearly did not producesigni_cant di}erences\ either in amplitudes or in latenciesof P199 waves in non!target responses[

However\ in spite of their statistical insigni_cance\ thedi}erences associated with the negative context in target

Fig[ 2[ Grand!averaged di}erence curves computed by subtracting ERPs evoked by non!target stimuli from ERPs evoked by target stimuli[ Figureconventions are the same as in Fig[ 0[ Black diamonds indicate the points of signi_cant di}erences between the curves recorded in {unsuccessful| trials"solid lines# and the control\ no!feedback trials "dotted lines#[

responses looked promising[ The concentration ofdi}erences within the P299 region indicated that theywere not entirely due to the random scatter[ In an attemptto remove some of the sources of uncontrolled amplitude~uctuations\ di}erence curves were computed by sub!tracting ERPs evoked by non!target stimuli from thoseevoked by target stimuli[ These di}erence curves\ grand!averaged for all subjects\ are shown in Fig[ 2 "_gure


conventions are the same as in Figs 0 and 1#[ All di}erencecurves show the distinct peaks of P199 and P299 com!ponents[ P199 amplitudes are clearly smaller in thedi}erence curves than in target responses\ whereas P299amplitudes are almost the same[ It is apparent that\ likein target ERPs\ dummy feedback a}ects predominantlythe P299 component[ The asymmetry between the e}ectsof positive and negative context seems to be even morepronounced in the di}erence curves] within the P299region the dashed lines "positive context# and the dottedlines "no feedback# are closer to each other than in targetERPs "Fig[ 0#[ In contrast\ the solid lines "negative con!text# show the marked di}erences[ Within the P199 regionthe di}erence curves show the e}ect that could not beseen in target ERPs] both types of dummy feedback "solidand dashed lines# reduce this component with respect tothe no feedback condition "dotted lines#[

The amplitudes and latencies of P299 and P199 com!ponents\ measured in the di}erence waves\ are presentedin Table 0[ A two!way ANOVA "electrode � context#showed a signi_cant e}ect of the type of context on theP299 amplitude "df �1\ F�2[00\ P³ 9[94#[ Post!hoctests showed that the amplitudes of P299 waves recordedwith negative context were signi_cantly smaller than theamplitudes recorded without the feedback "Bonferroni\P³ 9[933#[ Neither the di}erences in P299 peak latenciesnor the di}erences in P199 amplitudes and latencies weresigni_cant[

Black diamonds beneath the curves in Fig[ 2 indicatethe signi_cant di}erences between the correspondingpoints of negative context and no!feedback curves[ Atevery 13!ms\ within the range of 091 msÐ475 ms\ thecorresponding points of grand!averaged curves wereexpanded into sets of paired data "points of individualdi}erence curves# and compared with the Student{s t!test[All diamonds are clearly located within the P299 region[When the positive and negative context curves were com!

Table 0The e}ect of positive and negative context on the parameters of P299and P199 waves\ computed as a di}erence between potentials evokedby target and non!target stimuli[ Standard deviations are shown inparentheses beneath the mean values[

P299 P199

Amplitude Latency Amplitude LatencyðmVŁ ðmsŁ ðmVŁ ðmsŁ

Positive context 08[5 270[4 8[1 199[5"09[5# "16[4# "2[1# "05[2#

Negative context 04[8 275[2 8[8 193[9"7[1# "23[8# "1[7# "05[5#

No!feedback 11[0 274[1 09[9 190[2recordings "8[6# "07[9# "4[1# "05[2#

pared\ only one point of signi_cant di}erence was foundin the position of the second diamond in Pz recording[All the di}erences between the positive context curvesand the control no!feedback recordings failed to reachsigni_cance[

3[ Discussion

The present results demonstrate that being unsuc!cessful in the test "negative context# reduced the ampli!tude of the P299 potential[ Being successful "positivecontext# did not result in signi_cant di}erences[ It isunlikely that the enlargement caused by positive context\only failed to reach statistical signi_cance\ because theP299 amplitudes were slightly reduced rather thanenlarged in these trials[

Cognitive variables that are known to a}ect P299amplitude\ such as target stimulus probability or stimulusrepetition rate ð01\ 04Ł\ were constant in the experiment[The variables that could a}ect this amplitude were] thee}ect of the parallel task\ arousal level and emotion[

It was shown that the P299 amplitude was reduced byany parallel activity that competed for brain processingresources with the main experimental task ð5\ 6\ 02\ 03\08\ 10\ 14Ł[ Interviews with the subjects taking part in thisexperiment and the other experiments with real feedbackindicated that the process of using feedback informationincluded activities such as] the analysis of the internalstates of the brain during the last repetition of the targetstimulus\ the attempts to correlate them with the feedbackinformation\ the elaboration of the decision about whatto do next\ repetitive veri_cation and modi_cation ofthis decision etc[ These are all highly complex cognitiveprocesses that most likely recruit a large amount of pro!cessing resources and thereby limit the resources availablefor the main task of mental counting of target stimuli[Thus\ the general suppression of P299 amplitude couldbe expected[ The lack of suppression in positive contexttrials indicates the presence of other\ superimposed pro!cesses[

The enhancement of P299 amplitude by both positiveand negative emotions has been reported in a number ofother studies ð0\ 1\ 05Ð07\ 19\ 12\ 13\ 16Ð18Ł[ In all theseexperiments emotions were triggered directly by targetstimuli and there were no parallel activities[ The expla!nation of the present results can be based on the assump!tion that the enhancement\ produced by positive emotion\was strong enough to compensate for the e}ect of paralleltask but the enhancement produced by negative emotionwas signi_cantly weaker[ Is it likely that oppositeemotions change the P299 amplitude in the same direc!tion but with di}erent e}ectiveness< Chapman and co!authors found that positive words elicited larger ERPamplitudes than negative words for components in the199 msÐ319 ms latency range ð2\ 3Ł[ More recently\ Pal!


omba and co!authors ð13Ł noticed that pleasant stimulievoked slightly higher cortical positivity than unpleasantstimuli[ The di}erence did not reach the level of statisticalsigni_cance but the authors mentioned the e}ect as {evi!dent| ð13Ł[ ERPs associated with hitting the target with aphotoelectric gun were higher than those recorded whenthe target was missed ð21Ł[ The di}erence was statisticallysigni_cant and was found within the P299 latency rangebut the experimental design di}ered from the typical P299paradigm[ In all these studies\ the di}erences betweenpositive and negative emotions were smaller than pre!sently reported[ Thus\ the acceptance of the hypothesisof the interacting e}ects of parallel task and emotionleads to the conclusion that manipulated feedback ise}ective in producing di}erent emotional states[

It seems reasonable to assume that feedback experi!ments\ in which subjects attempt to control the amplitudeof their own brain potential\ produce higher arousal levelsthan the boring and aimless task of counting target stim!uli[ Available experimental data suggest that arousal\triggered by both pleasant and unpleasant stimuli\increases the P299 amplitude\ whereas relaxing stimuliseem to reduce it ð1\ 05\ 06\ 11\ 12\ 15Ł[ Arousal levelprobably in~uenced the results of the present experimentbut it does not readily explain the di}erence betweenpositive and negative context[ It seems unlikely that try!ing to achieve a good result and failing produces lessarousal than being successful from the beginning[ Thatis\ unless the subject gives up and loses interest[ Butcan such reactions occur within the time scale of thirtyrepetitions of target stimuli<

It seemed logical that experiments with {neutral| ran!dom feedback "49) {small| and 49) {big| feedback sig!nals# would provide the valuable reference[ Preliminaryexperiments in this laboratory have demonstrated thatthe amplitudes of P299 potentials\ recorded in suchexperiments\ did not di}er signi_cantly from amplitudesrecorded in no!feedback conditions[ The reports of thesubjects indicated that such {neutral| feedback sessionscould be interpreted as both success or failure dependingon the previous achievements[ If there were no previousexperiences\ the feeling of success or failure was probablyhighly in~uenced by the personality of the subject or thecurrent mood state[ Careful questioning and an increasein the number of feedback trials nearly uncovered thee}ect of the feedback manipulation[ Several subjects werelost to the experiment and the {neutral feedback| trialswere abandoned[

Random feedback procedures are often used to pro!vide a reference condition in the real feedback experi!ments ð20Ł[ The present results indicate that suchreference procedures should be treated with caution[Random feedback processing may involve complex pro!cesses and produce unexpected results[ No!feedback ref!erence can also introduce a di}erence due to the removalof the parallel task e}ect[ Perhaps the best strategy is to

use both controls\ but even than the interpretation of theresults can be complicated[

4[ Conclusion

Manipulated feedback is an interesting method of pro!ducing both positive and negative emotional states[ Theanalysis of the responses to neutral stimuli in di}erent\tonic emotional states directly addresses every day con!ditions[ Tonic emotional states a}ect the P299 potentialin a way that cannot be predicted from the responses toemotional stimuli[ The e}ects of positive and negativeemotional states may not be complementary[ This asym!metry can be explained by the interference of other pro!cesses\ such as the drain on central processing resources\but even then the additional assumption must be madethat the e}ects of positive and negative emotions di}erin strength[ Some indirect indications of such di}erencescan be found in the published literature[

Any attempt to use the present data for the interpret!ation of the real feedback e}ects would probably bepremature[ But at least they indicate how complicatedprocesses can be correlated with processing the feedbackinformation[

Acknowledgement

This research was supported by statutory grant of theNencki Institute[

References

ð0Ł Carretie� L\ Inglesias J[ ERP in response to facial expressions ofemotions[ Psychophysiology 0880^17]S05 "Abstract#[

ð1Ł Carretie� L\ Inglesias J[ An ERP study on the speci_city of facialexpression processing[ International Journal of Psychophysiology0884^08]072Ð81[

ð2Ł Chapman RM[ Connotative meaning and averaged evoked poten!tials[ In] Begleiter H\ editor[ Evoked brain potentials and behav!iour[ New York] Plenum\ 0868]060Ð85[

ð3Ł Chapman RM\ McCrary JW\ Chapman JA\ Martin JK[Behavioral and neural analyses of connotative meaning] wordclasses and rating scales[ Brain Language 0879^00]208Ð28[

ð4Ł Diamond SJ\ Farrington L[ Emotional response to _lms shown tothe right and left hemisphere of the brain measured by heart rate[Acta Psychologica 0867^30]144Ð59[

ð5Ł Donchin E\ Karis D\ Bashore TR\ Coles MGH\ Gratton G[ Cog!nitive psychophysiology and human information processing[ In]Coles MGH\ Donchin E\ Porges SW\ editors[ Psychophysiology]systems\ processes and applications[ New York] Guilford Press\0875]133Ð56

ð6Ł Donchin E\ Kramer A\ Wickens C[ Applications of brain event!related potentials to problems in engineering psychology[ In] ColesMGH\ Donchin E\ Porges SW\ editors[ Psychophysiology]systems\ processes and applications[ New York] Guilford Press\0875]691Ð07[

ð7Ł Eibl!Eibesfeldt I[ Human Ethology[ New York] Aldine de Gruyter\0878[


ð8Ł Gainotti G[ Emotional behavior and hemispheric side lesions[Cortex 0861^7]30Ð4

ð09Ł Gardner H[ The shattered mind[ New York] Knopf\ 0864[ð00Ł Goldstein K[ The Organism[ New York] American Book\ 0828[ð01Ł Hillyard SA\ Picton TW[ Event!related brain potentials and selec!

tive information processing in man[ In] Desmedt JE\ editor[ Cer!ebral evoked potentials in man[ Basel] Karger\ 0868]60Ð82[

ð02Ł Israel JB\ Chesney GL\ Wickens CD\ Donchin E[ P299 trackingdi.culty] Evidence for multiple resources in dual!task perform!ance[ Psychophysiology 0879^06]148Ð62[

ð03Ł Israel JB\ Wickens CD\ Chesney GL\ Donchin E[ The event!relatedpotential as an index of display monitoring workload[ HumanFactors 0879^11]101Ð13[

ð04Ł Johnson R Jr[ The amplitude of the P299 component of the event!related potential] review and synthesis[ In] Ackles PK\ JenningsRR\ Coles MGH\ editors[ Advances in psychophysiology\ vol 2\London] JAI Press\ 0876]58Ð026

ð05Ł Johnston VS\ Burleson M\ Miller DR[ Emotional value and latepositive components of ERPs[ In] Johnston R Jr\ Rohrbaugh JW\Parasuraman R\ editors[ Current trends in event!related potentialsresearch[ Amsterdam] Elsevier\ Electroencephalography and Clini!cal Neurophysiology\ 0876^S39]078Ð192[

ð06Ł Johnston VS\ Miller DR\ Burleson MH[ Multiple P2s to emotionalstimuli and their theoretical signi_cance[ Psychophysiology0875^12]573Ð83[

ð07Ł Johnston VS\ Wang XT[ The relationship between menstrual phaseand the P2 component of ERPs[ Psychophysiology 0880^17]399Ð8[

ð08Ł Kramer A\ Sirevaag E\ Braune R[ A psychophysiological assess!ment of operator workload during simulated ~ight missions[Human Factors 0876^18]034Ð59[

ð19Ł Laurian S\ Bader M\ Lanares J\ Oros L[ Topography of event!related potentials elicited by visual emotional stimuli[ InternationalJournal of Psychophysiology 0880^09]120Ð7[

ð10Ł Michalski A[ The e}ect of tonic pain on processing the non!painfulstimuli indexed by late components of event!related potentials[Acta Neurobiologiae Experimentalis 0887^47]44Ð53[

ð11Ł Miltner W\ Johnson R Jr\ Braun C\ Larbig W[ Somatosensoryevent!related potentials to painful and non!painful stimuli] e}ectsof attention[ Pain 0878^27]292Ð01[

ð12Ł Palomba D\ Angrilli A\ Bravi S[ Event!related potentials and heartrate changes to emotional pictorial stimuli[ Psychophysiology0882^29]S38 "Abstract#[

ð13Ł Palomba D\ Angrilli A\ Mini A[ Visual evoked potentials\ heartrate responses and memory to emotional pictorial stimuli[ Inter!national Journal of Psychophysiology 0886^16]44Ð56[

ð14Ł Polich J[ P299 from a passive auditory paradigm[ Electro!encephalography and Clinical Neurophysiology 0878^62]201Ð19[

ð15Ł Polich J\ Kok A[ Cognitive and biological determinants of P299]an integrative review[ Biological Psychology 0884^30]092Ð35[

ð16Ł Radilova� J\ Figar S\ Radil T[ Sexual arousal and visual perception[Activitas Nervosa Superior 0872^14]057Ð69[

ð17Ł Radilova� J\ Figar S\ Radil T[ Emotional states in~uence the visualevoked potentials[ Activitas Nervosa Superior 0873^15]048Ð59[

ð18Ł Radilova� J[ P299 and the emotional states studied by psycho!physiological methods[ International Journal of Psychophysiology0878^6]253Ð55[

ð29Ł Sackeim H\ Greenberg M\ Weiman A\ Gur R\ Hungerbuhler J\Geschwind N[ Functional brain asymmetry in the expression ofpositive and negative emotions] lateralization of insult in cases ofuncontrollable emotional outburst[ Archieves of Neurology0871^08]109Ð7[

ð20Ł Sommer W\ Schweinberger S[ Operant conditioning of P299[ Bio!logical Psychology 0881^22]26Ð38[

ð21Ł Sobo�tka S\ Grabowska A\ Grodzicka J\ Wasilewski R\ BudohoskaW[ Hemispheric asymmetry in event related potentials associatedwith positive and negative emotions[ Acta Neurobiologiae Exper!imentalis 0881^41]140Ð59[

ð22Ł Terzian H[ Behavioral and EEG e}ects of intracarotid sodiumamytal injections[ Acta Neurochirurgica 0853^01]129Ð8[

ð23Ł Vanderploeg RD\ Brown WS\ Marsh JT[ Judgments of emotionin words and faces] ERP correlates[ International Journal ofPsychophysiology 0876^3]082Ð194[

the effect of accomplishment and failure on p300 potentials evoked by neutral stimuli

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