Presentation on theme: "An fMRI study of Anomalous Anticipation of emotional stimuli Dick J. Bierman Universities of Amsterdam & Utrecht (NL) Toward a science of Consciousness."— Presentation transcript:
Was this just coincidence? Ed Cox (1960) Compared train ridership on days with and without a train accident. He found that on accident days there were significant less people on trains. (Note: Utts redid the analyses and found a smaller effect after correction for holidays)
1996: Empirical Approach: Presentiment experiment Presentiment is reported as the apparent psycho- physiological effect of a future emotional cause.
Procedure Subject sits relaxed with electrodes attached Gets about 40 exposures of randomized neutral and calm stimuli Skin conductance is averaged separately for emotional and neutral stimuli Before, during and after stimulus Baseline fixed at ~ -7.5 seconds
Procedure Presentiment trial Time Subject Hits Button 0 5 Or Calm Blank screen baseline Random!! Skin Conductance
Results First Subject (Radin-1) stimulus Presentiment? Calm Emotional BeforeDuring After
Results all Subjects (Radin-1) Emotional Calm Presentiment!
This should be everywhere! Main stream emotion research Measure baseline of dependent var Present an emotional / calm event Measure response of dependent var baselineeventresponse time
Mainstream Research questions R = f ( emotional level of event): Find f R = Response - BaseLine Implicit assumption: BaseLine is independent of future emotional level
What did we do? Search for main stream databases that Measure a BaseLine for at least 4 seconds. Use strong emotional events For which Data can be obtained
What did we find? Hamm group: on the speed with which fear arises in animal phobic patients Damasio group: on implicit emotional learning during Gambling task
Procedure Animal fear study Skin Conductance Fixation stimulus 7000 msec time 6850 msec Blank Screen 150 msec
Results re-analysis Hamms data Erotic Calm presentiment
Damasio: gambling procedure Participant gets initially $2000 Draws cards from one of 4 different decks Card is either winning or losing time Preparation Draws card Feedback: win or loss Skin Conductance
Damasio dataset analyses Damasio-analysis P = f (type of deck) !!! Advantageous vs non-advantageous Our Re-analysis: P = f(type of Card) Winning vs Losing
Winning vs. Losing Cards: Quote from: Bechara, Damasio et al, Science, 275, 28 February 97, 1293-1295 : ….. the players have no way of predicting when a penalty will arise…
Results re-analysis Gambling experiment t = 1.634; df=117 ; p =0.053 Presentiment effect : 20%!!!!
So What Next? Can we differentiate between different emotions? Can we exclude possible artefacts? Can we locate the source of this phenomenon?
Event Related Design 10 subjects 48 pictures (events) ~ 16 neutral, ~ 8 erotic, ~ 8 violent 4.2 seconds exposure time 16.8 seconds for one trial (= 8 volumescans) 1 vol: 22 slices, slice resolution: 64 * 64
Analysis procedure (1) Dependent var: BOLD signal per voxel (Blood Oxygenation Level Dependent) Pre-processing: –Slice time correction –Linear trend removal –8 mm spatial smooting –No further smoothing in time domain
Analysis Procedure General Linear Model –Predictors : neutral stim, erotic stim, violent stim. Results in: –Regions of Interest with significant fit. Event related averaging over stim.condition t-test of average BOLD signals in ROI
Brain regions which have a significant fit with emotional stims and neutral stim as predictor Contrast between emotional and neutral conditon.
Plot for BOLDsignal for the whole experiment Brain-map with ROIs Event related averaging erotic neutral stimulus Erotic Presentiment effect at time: -4 seconds. Td = 2.89 df= 39 p < 0.01
Normal explanations Chance fluke, weak effects, over analysis Incorrect Randomization –With replacement –Subject strategies Introduced by software –Hemodynamic curve –smoothing
Conclusion This study should be seen as exploratory Warrants further research Most fmri emotional pictures research sh/could look at this effect if: –Randomization with replacement –Strong stimuli –Reasonable ISI (~ 18 seconds)
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