Affective startle modulation in anticipation and perception
Affective startle modulation in anticipation and perception
Affective startle modulation in anticipation and perception
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Psychophysiology, 38 ~2001!, 719–722. Cambridge University Press. Pr<strong>in</strong>ted <strong>in</strong> the USA.<br />
Copyright © 2001 Society for Psychophysiological Research<br />
BRIEF REPORT<br />
<strong>Affective</strong> <strong>startle</strong> <strong>modulation</strong> <strong>in</strong> <strong>anticipation</strong> <strong>and</strong> <strong>perception</strong><br />
DEAN SABATINELLI, MARGARET M. BRADLEY, <strong>and</strong> PETER J. LANG<br />
National Institute of Mental Health Center for the Study of Emotion <strong>and</strong> Attention, University of Florida, Ga<strong>in</strong>esville, USA<br />
Abstract<br />
Startle <strong>modulation</strong> was <strong>in</strong>vestigated as participants first anticipated <strong>and</strong> then viewed affective pictures <strong>in</strong> order to<br />
determ<strong>in</strong>e whether affective <strong>modulation</strong> of the <strong>startle</strong> reflex is similar <strong>in</strong> these different task contexts. Dur<strong>in</strong>g a 6-s<br />
<strong>anticipation</strong> period, a neutral light cue signaled whether the upcom<strong>in</strong>g picture would portray snakes, erotica, or<br />
household objects; at the end of the anticipatory period, a picture <strong>in</strong> the signaled category was viewed for 6 s. Male<br />
participants highly fearful of snakes were recruited to maximize emotional arousal dur<strong>in</strong>g <strong>anticipation</strong> <strong>and</strong> <strong>perception</strong>.<br />
Results <strong>in</strong>dicated that the <strong>startle</strong> reflex was potentiated when anticipat<strong>in</strong>g either unpleasant ~phobic! or pleasant ~erotic!<br />
pictures, compared to neutral stimuli, whereas dur<strong>in</strong>g <strong>perception</strong>, reflexes were potentiated when view<strong>in</strong>g unpleasant<br />
stimuli, <strong>and</strong> reduced when view<strong>in</strong>g pleasant pictures. The <strong>startle</strong> reflex is modulated by hedonic valence <strong>in</strong> picture<br />
<strong>perception</strong>, <strong>and</strong> by emotional arousal <strong>in</strong> a task context <strong>in</strong>volv<strong>in</strong>g picture <strong>anticipation</strong>.<br />
Descriptors: Emotion, Anticipation, Startle reflex, <strong>Affective</strong> pictures<br />
The magnitude of the <strong>startle</strong> reflex covaries with hedonic valence<br />
dur<strong>in</strong>g stimulus <strong>perception</strong>. <strong>Affective</strong> <strong>modulation</strong> of the <strong>startle</strong><br />
reflex is found when people view pictures or films, listen to<br />
sounds, or smell odors ~for an overview, see Bradley, Cuthbert, &<br />
Lang, 1999!. In each case, larger reflexes are elicited when process<strong>in</strong>g<br />
unpleasant stimuli, compared to pleasant stimuli. Furthermore,<br />
these modulatory differences are greatest for unpleasant <strong>and</strong><br />
pleasant stimuli that are rated as highly arous<strong>in</strong>g ~Cuthbert, Bradley,<br />
& Lang, 1996!. We have suggested that reflex <strong>modulation</strong><br />
dur<strong>in</strong>g <strong>perception</strong> reflects motivational prim<strong>in</strong>g, <strong>in</strong> which activation<br />
of the defensive motivational system by an unpleasant stimulus<br />
primes related reflexes, such as the <strong>startle</strong> reflex ~Lang,<br />
Bradley, & Cuthbert, 1997!.<br />
Potentiation of the bl<strong>in</strong>k reflex has also been found when<br />
participants simply anticipate the occurrence of an unpleasant<br />
event, such as <strong>in</strong>tense noise ~Patrick & Berthot, 1995! or shock<br />
~Grillon, Ameli, Woods, Merikangas, & Davis, 1991!. Determ<strong>in</strong><strong>in</strong>g<br />
whether potentiation dur<strong>in</strong>g aversive <strong>anticipation</strong> is related to stimulus<br />
unpleasantness or to stimulus arousal relies on assess<strong>in</strong>g<br />
reflex magnitude dur<strong>in</strong>g the <strong>anticipation</strong> of a similarly arous<strong>in</strong>g<br />
pleasant stimulus. Studies of <strong>startle</strong> <strong>modulation</strong> dur<strong>in</strong>g <strong>anticipation</strong><br />
have not typically <strong>in</strong>cluded pleasant stimuli, due at least <strong>in</strong><br />
This work was supported <strong>in</strong> part by National Institute of Mental Health<br />
grants MH37757 <strong>and</strong> MH43975 <strong>and</strong> P50-MH52384, a NIMH Behavioral<br />
Science grant to the Center for the Study of Emotion <strong>and</strong> Attention<br />
~CSEA!, University of Florida, Ga<strong>in</strong>esville, Florida.<br />
Address repr<strong>in</strong>ts requests to: Margaret M. Bradley, Box 100165 HSC,<br />
University of Florida, Ga<strong>in</strong>esville, FL 32610-0165, USA. E-mail: bradley@<br />
ufl.edu.<br />
719<br />
part to difficulties <strong>in</strong> identify<strong>in</strong>g an arous<strong>in</strong>g appetitive stimulus<br />
that is also <strong>in</strong> the same sensory modality as an electric shock or a<br />
noise blast. Here, we measured the magnitude of the <strong>startle</strong> reflex<br />
while participants anticipated the presentation of highly arous<strong>in</strong>g<br />
unpleasant or pleasant pictures. Pictures were used as stimuli<br />
because numerous studies have confirmed that <strong>perception</strong> of these<br />
stimuli elicits emotional reactions <strong>in</strong> self-report, physiological, <strong>and</strong><br />
behavioral systems ~e.g., Lang, Greenwald, Bradley, & Hamm,<br />
1993!.<br />
Compared to the <strong>anticipation</strong> of an <strong>in</strong>tense unconditioned stimulus<br />
such as electric shock ~Grillon et al., 1991!, pictures may be<br />
less likely to engage strong anticipatory responses. Thus, <strong>in</strong> the<br />
present study, we selected picture stimuli that were maximally<br />
arous<strong>in</strong>g. Previous research ~e.g., Hamm, Cuthbert, Globisch, &<br />
Vaitl, 1997! has found that aversive respond<strong>in</strong>g is heightened when<br />
fearful participants view fear-related pictures; therefore the present<br />
study presented pictures of snakes to participants report<strong>in</strong>g high<br />
snake fear. For pictures rated as pleasant, erotic materials elicit the<br />
strongest affective reactions, particularly for men ~Bradley, Codispoti,<br />
Sabat<strong>in</strong>elli, Cuthbert, & Lang, 2000!, who were recruited as<br />
participants <strong>in</strong> the current study.<br />
Each trial consisted of an <strong>anticipation</strong> <strong>and</strong> a <strong>perception</strong> period.<br />
Dur<strong>in</strong>g each 6-s anticipatory period, one of three cue lights signaled<br />
that the upcom<strong>in</strong>g picture would depict either snakes, erotica,<br />
or household objects. Follow<strong>in</strong>g <strong>anticipation</strong>, the picture was<br />
presented for 6 s. An acoustic <strong>startle</strong> probe was presented <strong>in</strong> the<br />
latter half of the <strong>anticipation</strong> or <strong>perception</strong> period, <strong>and</strong> the reflexive<br />
eyebl<strong>in</strong>k response measured. If the <strong>startle</strong> reflex is modulated by<br />
picture content similarly <strong>in</strong> <strong>anticipation</strong> <strong>and</strong> <strong>perception</strong>, reflexes<br />
elicited when anticipat<strong>in</strong>g unpleasant ~snake! pictures will be larger
720 D. Sabat<strong>in</strong>elli, M.M. Bradley, <strong>and</strong> P.J. Lang<br />
than those elicited when anticipat<strong>in</strong>g pleasant ~erotic! pictures.<br />
Conversely, if reflex <strong>modulation</strong> dur<strong>in</strong>g <strong>anticipation</strong> is primarily<br />
sensitive to emotional arousal, reflexes will be potentiated when<br />
anticipat<strong>in</strong>g emotionally arous<strong>in</strong>g ~pleasant or unpleasant!, compared<br />
to neutral, stimuli. As larger electrodermal responses have<br />
been found when anticipat<strong>in</strong>g ~Simons, Öhman, & Lang, 1979! or<br />
perceiv<strong>in</strong>g ~e.g., Bradley et al., 1999; Lang et al., 1993! affectively<br />
arous<strong>in</strong>g stimuli, this measure was <strong>in</strong>cluded here to assess the<br />
specificity of the <strong>startle</strong> reflex as an <strong>in</strong>dex of affective process<strong>in</strong>g.<br />
Method<br />
Participants<br />
Thirty-two male University of Florida students were recruited<br />
after be<strong>in</strong>g identified as meet<strong>in</strong>g a prelim<strong>in</strong>ary criterion of elevated<br />
snake fear. Participation was voluntary <strong>and</strong> compensated<br />
with course credit or a payment of $10. After complet<strong>in</strong>g the<br />
procedure, all participants filled out a snake fear questionnaire<br />
~SNAQ; Klorman, Weerts, Hast<strong>in</strong>gs, Melamed, & Lang, 1974!.<br />
Twenty-four participants fall<strong>in</strong>g above the 85th percentile of snake<br />
fear for men were accepted <strong>in</strong>to the f<strong>in</strong>al group ~f<strong>in</strong>al SNAQ<br />
mean 13.5, SD 5!.<br />
Materials <strong>and</strong> Design<br />
Forty-eight color pictures were selected from the International<br />
<strong>Affective</strong> Picture System 1 ~Center for the Study of Emotion <strong>and</strong><br />
Attention, 1999!, <strong>in</strong>clud<strong>in</strong>g equal numbers of erotic, household<br />
object, <strong>and</strong> snake scenes. In addition to three practice pictures, five<br />
blocks of n<strong>in</strong>e pictures were arranged such that three pictures from<br />
each category were presented r<strong>and</strong>omly <strong>in</strong> a block. Three presentation<br />
orders were developed such that, across participants, each<br />
picture was seen equally often <strong>in</strong> the first, second, or third portion<br />
of each block. Pictures were presented us<strong>in</strong>g a Kodak Ektagraphic<br />
III AM slide projector situated adjacent to the experimental room.<br />
A slide screen hung approximately 2m<strong>in</strong>front of the participant,<br />
with three clear lights arranged horizontally above the screen,<br />
20 cm apart from each other. Each of the three lights was used to<br />
cue the presentation of a specific category of pictures ~snakes,<br />
erotica, or household objects!, counterbalanced across participants.<br />
Each trial consisted of a 6-s anticipatory <strong>in</strong>terval, dur<strong>in</strong>g which one<br />
of the three lights was cont<strong>in</strong>uously lit, followed by a6s<strong>perception</strong><br />
period, <strong>in</strong> which a picture <strong>in</strong> the cued category was presented.<br />
Intertrial <strong>in</strong>tervals ranged from 10 to 20 s.<br />
The acoustic <strong>startle</strong> probe consisted of a 99 dB, 50-ms presentation<br />
of white noise, with <strong>in</strong>stantaneous rise time, produced by a<br />
Coulbourn S81-02 noise generator, gated through a Coulbourn<br />
S82-24 amplifier, <strong>and</strong> presented over matched Telephonics TDH-49<br />
headphones. Of the 43 <strong>startle</strong> stimuli presented, 24 occurred dur<strong>in</strong>g<br />
the 6-s <strong>anticipation</strong> <strong>in</strong>terval ~4,000 or 5,500 ms after cue onset!,<br />
8 for each of the three picture categories. Twelve probes were<br />
presented dur<strong>in</strong>g the 6-s <strong>perception</strong> <strong>in</strong>terval ~3,500 or 4,000 ms<br />
1 The International <strong>Affective</strong> Picture System ~IAPS! is available on<br />
CD-ROM <strong>and</strong> as photographic slides. The stimulus sets <strong>and</strong> technical<br />
manual ~CSEA, 1999! can be obta<strong>in</strong>ed on request from Margaret M.<br />
Bradley or Peter J. Lang, NIMH Center for the Study of Emotion <strong>and</strong><br />
Attention, Box 100165 HSC, University of Florida, Ga<strong>in</strong>esville, FL 32610-<br />
0165, USA.<br />
IAPS numbers used <strong>in</strong> this study were: Erotica: 4210, 4220, 4232,<br />
4290, 4300, 4310, 4607, 4608, 4651, 4652, 4655, 4664, 4680, 4800, 4810;<br />
Household objects: 7002, 7006, 7009, 7025, 7030, 7034, 7040, 7140, 7190,<br />
7217, 7224, 7234, 7235, 7490, 7900; Snakes: 1000, 1010, 1020, 1030,<br />
1040, 1050, 1070, 1080, 1090, 1100, 1110, 1111, 1112, 1113, 1120.<br />
after picture onset!, four for each picture category. Three probes<br />
were presented dur<strong>in</strong>g practice trials, <strong>and</strong> four probes were presented<br />
dur<strong>in</strong>g <strong>in</strong>tertrial <strong>in</strong>tervals. N<strong>in</strong>e non-probed trials were also<br />
<strong>in</strong>cluded.<br />
Physiological Record<strong>in</strong>g <strong>and</strong> Data Reduction<br />
Stimulus control <strong>and</strong> physiological data acquisition were accomplished<br />
us<strong>in</strong>g an IBM-compatible computer runn<strong>in</strong>g VPM software<br />
~Cook, 1994!.<br />
The eyebl<strong>in</strong>k component of the <strong>startle</strong> reflex was recorded<br />
electromyographically from the orbicularis oculi muscle beneath<br />
the left eye, us<strong>in</strong>g m<strong>in</strong>iature SensorMedics Ag0AgCl electrodes<br />
placed 1.5 cm apart. The raw signal was amplified by 30,000 <strong>and</strong><br />
b<strong>and</strong>-pass filtered at 90–250 Hz us<strong>in</strong>g a Coulbourn S75-01 amplifier.<br />
The amplified signal was then rectified <strong>and</strong> <strong>in</strong>tegrated us<strong>in</strong>g<br />
a Coulbourn S76-01 contour-follow<strong>in</strong>g <strong>in</strong>tegrator set at an actual<br />
time constant of 123 ms, <strong>and</strong> sampled at 20 Hz beg<strong>in</strong>n<strong>in</strong>g 3 s<br />
before each trial. Sampl<strong>in</strong>g <strong>in</strong>creased to 1000 Hz 50 ms prior to the<br />
onset of the <strong>startle</strong> probe <strong>and</strong> cont<strong>in</strong>ued for 250 ms. Sampl<strong>in</strong>g then<br />
cont<strong>in</strong>ued at 20 Hz until 3 s after picture offset. Startle bl<strong>in</strong>ks were<br />
scored off-l<strong>in</strong>e with an <strong>in</strong>teractive computer program that scored<br />
onset latency <strong>and</strong> peak.<br />
Sk<strong>in</strong> conductance was transduced with SensorMedics st<strong>and</strong>ard<br />
electrodes filled with a 0.05 molar NaCl0Unibase cream electrolyte<br />
affixed to the hypothenar em<strong>in</strong>ence of the left palm. A Coulbourn<br />
S71-22 sk<strong>in</strong> conductance coupler provided a constant 0.5 V<br />
across the two electrodes. After log transformation, change scores<br />
were calculated for sk<strong>in</strong> conductance by subtract<strong>in</strong>g the mean<br />
activity <strong>in</strong> the 1 s preced<strong>in</strong>g cue-light onset from the average<br />
response dur<strong>in</strong>g each of the 6-s <strong>anticipation</strong> <strong>and</strong> 6-s <strong>perception</strong><br />
<strong>in</strong>tervals.<br />
Procedure<br />
The physiological sensors were attached while the participant<br />
recl<strong>in</strong>ed <strong>in</strong> a comfortable chair. The participant was then told<br />
which of the three cue lights ~left, middle, right! would signal<br />
whether the upcom<strong>in</strong>g picture would <strong>in</strong>volve snakes, household<br />
objects, or erotica. Picture onset co<strong>in</strong>cided with cue-light offset,<br />
<strong>and</strong> participants were <strong>in</strong>structed to look at the picture the entire<br />
time it was on the screen, <strong>and</strong> to ignore occasional noises presented<br />
over the headphones. Follow<strong>in</strong>g the session, participants filled out<br />
the SNAQ <strong>and</strong> three other questionnaires, <strong>and</strong> were debriefed.<br />
Data Analysis<br />
A23 repeated-measures analysis of variance was conducted for<br />
bl<strong>in</strong>k magnitude <strong>and</strong> sk<strong>in</strong> conductance change <strong>in</strong>dividually, with<br />
Process<strong>in</strong>g Period ~<strong>anticipation</strong>, <strong>perception</strong>!, <strong>and</strong> Picture Content<br />
~erotica, household object, snake! as with<strong>in</strong>-subjects factors. For<br />
repeated-measures analyses, a Greenhouse–Geisser correction was<br />
used when appropriate.<br />
Results<br />
Startle Reflex<br />
Modulation of the <strong>startle</strong> reflex by picture content differed <strong>in</strong><br />
<strong>anticipation</strong> <strong>and</strong> <strong>perception</strong>, as <strong>in</strong>dicated by a significant Period<br />
~<strong>anticipation</strong>, <strong>perception</strong>! Content ~erotic, household object, or<br />
snake pictures! <strong>in</strong>teraction, F~2,46! 5.13, p .05, E .96 ~see<br />
Figure 1!.<br />
Dur<strong>in</strong>g <strong>anticipation</strong>, the <strong>startle</strong> reflex was modulated by picture<br />
content, F~2,46! 5.03, p .05, E .89, with larger bl<strong>in</strong>ks<br />
elicited when anticipat<strong>in</strong>g either pictures of erotica or snakes,
Reflex <strong>modulation</strong> <strong>in</strong> <strong>anticipation</strong> <strong>and</strong> <strong>perception</strong> 721<br />
Figure 1. Top panel: Startle bl<strong>in</strong>k magnitude when anticipat<strong>in</strong>g the presentation<br />
of pictures of erotica, household objects, or snakes ~left!, <strong>and</strong><br />
dur<strong>in</strong>g <strong>perception</strong> of these pictures ~right!. Bottom panel: Sk<strong>in</strong> conductance<br />
change when anticipat<strong>in</strong>g the presentation of pictures of erotica, household<br />
objects, or snakes ~left! <strong>and</strong> dur<strong>in</strong>g <strong>perception</strong> of these pictures ~right!.<br />
compared to neutral pictures, quadratic F~1,23! 6.77, p .05. 2<br />
Compared to anticipat<strong>in</strong>g neutral pictures, bl<strong>in</strong>ks were clearly<br />
potentiated when anticipat<strong>in</strong>g erotica, F~1,23! 7.86, p .05,<br />
marg<strong>in</strong>ally potentiated when anticipat<strong>in</strong>g snakes, F~1,23! 4.01,<br />
p .06, <strong>and</strong>, importantly, bl<strong>in</strong>ks elicited when anticipat<strong>in</strong>g erotic<br />
<strong>and</strong> snake pictures did not differ.<br />
Dur<strong>in</strong>g picture view<strong>in</strong>g, bl<strong>in</strong>k magnitude was aga<strong>in</strong> related to<br />
picture valence, F~2,46! 3.75, p .05, E .87, but, as expected,<br />
this relationship was l<strong>in</strong>ear rather than quadratic, <strong>in</strong> that larger<br />
bl<strong>in</strong>ks were elicited when view<strong>in</strong>g pictures of snakes, compared to<br />
when view<strong>in</strong>g erotica, F~1,23! 5.73, p .05. Compared to<br />
2 Includ<strong>in</strong>g probe delay ~4 s or 5.5 s follow<strong>in</strong>g cue onset! <strong>in</strong> the analysis<br />
of <strong>startle</strong> magnitude dur<strong>in</strong>g picture <strong>anticipation</strong> yielded a marg<strong>in</strong>al <strong>in</strong>teraction<br />
of picture content <strong>and</strong> probe delay, F~2,46! 2.96, p .08.<br />
However, because <strong>startle</strong> <strong>modulation</strong> dur<strong>in</strong>g <strong>anticipation</strong> has been shown to<br />
be highly sensitive to the tim<strong>in</strong>g of stimulus onset ~e.g., Anthony &<br />
Putnam, 1985!, follow-up tests were conducted. Picture content affected<br />
bl<strong>in</strong>k magnitude at each delay, F~2,46! 3.77, p .05 for 4-s probes;<br />
F~2,46! 4.12, p .05 for 5.5-s probes. At the earlier probe time, larger<br />
bl<strong>in</strong>ks were elicited dur<strong>in</strong>g <strong>anticipation</strong> of erotic, compared to snake,<br />
pictures, F~1,23! 10.69, p .01. At the later probe position, bl<strong>in</strong>ks were<br />
potentiated when anticipat<strong>in</strong>g erotic <strong>and</strong> snake pictures, compared to household<br />
object picture <strong>anticipation</strong>, quadratic F~2,46! 7.20, p .05. Bl<strong>in</strong>k<br />
magnitude did not significantly change as a function of probe delay when<br />
anticipat<strong>in</strong>g either erotica or snakes.<br />
household object pictures, bl<strong>in</strong>ks were significantly <strong>in</strong>hibited when<br />
view<strong>in</strong>g erotica, F~1,23! 5.16, p .05. Bl<strong>in</strong>ks elicited when<br />
view<strong>in</strong>g snake pictures were not potentiated, compared to neutral<br />
pictures, for the group as a whole. However, for highly fearful<br />
participants ~e.g., scores above the 95th percentile of snake fear;<br />
n 8!, reliable <strong>startle</strong> potentiation was obta<strong>in</strong>ed for snake, compared<br />
to neutral, pictures, F~2,14! 7.33, p .01.<br />
Sk<strong>in</strong> Conductance<br />
As expected, sk<strong>in</strong> conductance change varied with picture content,<br />
F~2,46! 16.60, p .001, E .78. Larger electrodermal changes<br />
occurred when anticipat<strong>in</strong>g or view<strong>in</strong>g emotional ~erotic or snake!<br />
compared to neutral, pictures, quadratic F~1,23! 18.30, p <br />
.001, an effect that was significant <strong>in</strong> both <strong>anticipation</strong>, F~1,23! <br />
9.37, p .01, <strong>and</strong> <strong>perception</strong>, F~1,23! 18.96, p .001. A<br />
significant <strong>in</strong>teraction of period <strong>and</strong> content, F~2,46! 3.56, p <br />
.05, E .99, <strong>in</strong>dicated that although responses to erotica were<br />
elevated compared to household objects <strong>in</strong> <strong>anticipation</strong>, F~1,23! <br />
16.36, p .001, <strong>and</strong> <strong>perception</strong>, F~1,23! 20.01, p .001,<br />
responses to snakes were elevated <strong>in</strong> <strong>perception</strong> only, F~1,23! <br />
9.39, p .01.<br />
Discussion<br />
Startle reflex magnitude dur<strong>in</strong>g <strong>anticipation</strong> reflected the emotional<br />
arousal of the expected stimulus, rather than its hedonic<br />
valence. Anticipat<strong>in</strong>g an emotionally arous<strong>in</strong>g picture, compared<br />
to a neutral picture, augmented <strong>startle</strong> magnitude, regardless of<br />
whether the upcom<strong>in</strong>g picture was pleasant or unpleasant. Reflex<br />
potentiation dur<strong>in</strong>g aversive <strong>anticipation</strong> replicates prior studies<br />
that have used shock as the predicted stimulus ~e.g., Grillon et al.,<br />
1991!, <strong>in</strong>dicat<strong>in</strong>g that fearful pictures prompt similar anticipatory<br />
<strong>modulation</strong>. The current data suggest, however, that the <strong>startle</strong><br />
reflex is also potentiated dur<strong>in</strong>g <strong>anticipation</strong> of highly arous<strong>in</strong>g<br />
pleasant stimuli, specifically as men anticipated the presentation of<br />
pictures of erotica. This pattern of <strong>startle</strong> <strong>modulation</strong> differs from<br />
the widely replicated effect found dur<strong>in</strong>g picture <strong>perception</strong>, <strong>in</strong><br />
which smaller bl<strong>in</strong>ks occur when view<strong>in</strong>g pleasant, compared to<br />
unpleasant pictures. Indeed, once the anticipated erotic picture was<br />
presented, <strong>startle</strong> magnitude became <strong>in</strong>hibited relative to neutral<br />
<strong>and</strong> unpleasant pictures. Electrodermal activity, on the other h<strong>and</strong>,<br />
showed consistently greater responses when anticipat<strong>in</strong>g or perceiv<strong>in</strong>g<br />
erotic, relative to neutral, pictures.<br />
There was no evidence that <strong>anticipation</strong> of engag<strong>in</strong>g stimuli <strong>in</strong><br />
the visual modality ~i.e., erotic pictures! accentuated reflex <strong>in</strong>hibition<br />
to an acoustic <strong>startle</strong> probe, as a modality-directed attention<br />
account might predict ~Anthony & Graham, 1985!. Rather, as<br />
noted above, reflexes were significantly larger when anticipat<strong>in</strong>g<br />
erotic, compared to neutral, pictures, <strong>and</strong> furthermore, were equivalent<br />
when anticipat<strong>in</strong>g either snake or erotic stimuli. It is possible,<br />
of course, that this anticipatory pattern is unique to men who are<br />
fearful of snakes. However, the fact that electrodermal <strong>and</strong> <strong>startle</strong><br />
responses dur<strong>in</strong>g picture <strong>perception</strong> were completely consistent<br />
with previous data from unselected participants ~e.g., Bradley<br />
et al., 1999! argues aga<strong>in</strong>st this hypothesis.<br />
Although previous studies have found <strong>startle</strong> <strong>modulation</strong> by<br />
hedonic valence <strong>in</strong> the absence of a picture stimulus, these effects<br />
have been obta<strong>in</strong>ed follow<strong>in</strong>g the presentation of a specific picture<br />
stimulus. For example, <strong>startle</strong> cont<strong>in</strong>ues to be modulated by hedonic<br />
valence if the participant is <strong>in</strong>structed to ma<strong>in</strong>ta<strong>in</strong> a mental<br />
image of a just-presented picture ~Schupp, Cuthbert, Bradley,<br />
Birbaumer, & Lang, 1997!, or if a picture is briefly presented
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~500 ms! <strong>and</strong> <strong>startle</strong> reflexes are elicited shortly after picture offset<br />
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Center for the Study of Emotion <strong>and</strong> Attention ~CSEA-NIMH!. ~1999!.<br />
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Ga<strong>in</strong>esville, FL, The Center for Research <strong>in</strong> Psychophysiology, University<br />
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~Received July 25, 2000; Accepted January 4, 2001!