IntroductionThe somatic marker hypothesis (Damasio, 1994) suggests that physiological changes in response to alternative choices provide useful, perhaps indispensible, input during an intuitive decision making process.

We expect that: physiological changes during stimulus presentation predict choices; people with a more acute sense of their own physiological changes (detectors) perform better on intuitive decision making tasks than non-detectors.

We compared performance of detectors and non-detectors on two measures of intuition: • intuition questionnaire (Taggart & Valenzi, 1981)• implicit grammar task. (Cleeremans et al., 1998 )

Method• 62 participants (22 male, 40 female)• 20 detectors,42 non-detectors classified on basis of performance on a heartbeat detection task (Wiens & Palmer, 2001)

Intuition questionnaireThirty statements on an intuitive or a rational approach.Participants indicate occurrence (never to always) on 6 point scale

Implicit grammar task• Sixty trials, self-paced•Two excluding algorithms (‘grammars’) generate words with different letter orders •Participants learn implicitly through trial by trial feedback to discriminate between exemplars of the two grammars

AcknowledgmentsA thank you to the psychology students

Nathalie FrankeMarlou HamersmaBart van der HelEva JesmiatkaFloortje van der Meer MohrWouter PronkSanne SchepersAlina Talhof

for cheerfully collecting the data.

ResultsMore men (55%) than women (20%) were heartbeat detectors (exact p = .01, two-sided).

Detectors did not differ from non-detectors on the three intuition scales of the intuition questionnaire, but scored non-significantly higher on all three ratio scales.

There was no significant learning on the grammar task, and detectors and non-detectors did not differ on total grammar scores.

A 2 (type of word) * 2 (hit or miss) * 2 (first or second interbeat interval) repeated measures ANOVA showed a significant 3-way interaction (F(1,61) = 3.98, p=.05), due to a change in heartrate from first to second heartbeat interval while participants viewed the word they would choose later, regardless of whether that was the correct word or not. (Fig 2)

ConclusionsPhysiological changes – such as changes in heartrate – while looking at a stimulus, appear to be related to future choices, as the somatic marker hypothesis suggests.

Detectors (people with a more acute sense of their own physiological processes) do not perform better on tasks that involve intuitive decision making.

Exploratory analyses suggests that detectors may be more rational than non-detectors, suggesting a link between anxiety control and sensitivity to physiological changes.

Caveats The grammar task that was designed to trigger implicit learning failed overall to produce learning in our participants. We could therefore not test whether the heartrate changes prior to choice would still occur when learning had taken place. If learning had taken place more generally, we might have seen a performance difference between detectors and non-detectors. However, the results of the intuition questionnaire make this less likely.In previous studies, performance of heartbeat detectors in implicit learning tasks showed mixed results; in some they performed better, in others there was no difference. (Katkin, Wiens, and Öhman, 2001, Wiens, Katkin, and Öhman, 2003). These mixed results may be a clue that heartbeat detectors are a mixed bunch as well. Their enhanced sensitivity may produce fear in some and an enhanced intuition in others.

Next At present we investigate whether a ten-day meditation retreat affects heartbeat detection and performance on implicit learning. We have included questionnaires on somatic complaints and neuroticism to discover whether sensitivity to physiological changes may be related to rationally repressed fear in some, but not in other detectors. We would predict performance on intuitive decisions to be best for detectors that do not feel unpleasant about their heightened sensitivity.

Exploring the role of the heart during an intuitive decision making task

Eva Lobach and Dick BiermanUniversity of Amsterdam and University for Humanistics, Utrecht

Figure 2. Heartrate (beats per minute) was calculated from the interbeat interval that included stimulus onset (IBI 1) and the following interbeat interval (IBI 2).Heartrate showed an increase during the stimulus word that the participant would later choose.

For further informationPlease contact Eva Lobach e.lobach@uva.nl, or Dick Bierman d.j.bierman@uva.nlPsychology Department, University of AmsterdamRoetersstraat 151018 WB Amsterdam Phone: +31 (0)20 525 7015 (Eva) or +31 (0)20 525 6727 (Dick)

Wiens, S., Katkin, E.S., & Öhman, A. (2003). Effects of trial order and differential conditioning on acquisition of differential shock expectancy and skin conductance conditioning to masked stimuli. Psychophysiology, 40, 989-997.

ReferencesCleeremans, A., Destrebecqz, A., and Boyer, M. (1998) Implicit learning: News

from the front. Trends in Cognitive Sciences 5, 406 – 416.Damasio, A.R. (1994) Descartes Error. Emotion, Reason and the Human Brain.

New York: Grosset/Putman.Taggart, W. en Valenzi, E. (1990). Assessing rational and intuitive styles: a

human information processing metaphor. Journal of Management Studies, Vol.27, Nr.2, 149-172.

Katkin, E. S., Wiens, S., & Öhman, A. (2001). Nonconscious fear conditioning, visceral perception, and the development of gut feelings. Psychological Science, 12, 366-370.

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Figure 1. Course of one trial with sample stimuli of the two different grammars

Exploratory analyses

We were surprised that the heartbeat detectors did not show any indication of being more intuively inclined.To explore this further, we compared detectors and non-detectors on all 30 items of the intuition questionnaire.Fig 5 shows the five items on which detectors scored significantly different (ps < .05, two-tailed) from non-detectors.

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Figure 3 & 4. Heartrate (beats per minute) was calculated from the interbeat interval that included stimulus onset (IBI 1) and the next interbeat interval (IBI 2).Heartrate showed an increase while viewing the stimulus word that the participant would later choose, but only for non-detectors.

Figure 5. The five items (out of 30) of the intuition questionnaire on which heartbeat detectors differed significantly (ps<.05, two-tailed) from non-detectors. (N = 65)

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I prefer to receive explicit instructions

I trust upon rules and procedures

Following procedures determines my success

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I prefer work that involves co-operation

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This same analysis for detectors and non-detectors separately showed the same significant interaction, but for non-detectors only (F(1,41)=5.03, p = .03).(Figs 3&4).