Use of Brain Imaging Technology in Investigating the Relationship between Biological Factors and Behavior

1. Use of Brain Imaging Technology in Investigating the Relationship between Biological Factors and Behavior IB Psychology

2. Brain Imaging Technologies • EEG • CAT • PET • MRI • fMRI

3. EEG (Electroencephalogram)

4. CAT Scan

5. PET Scan

6. MRI Scan

7. fMRI Scan

8. Advantages of fMRI Scans • Most hospitals already have MRI scanners, and they are easily converted to fMRI scanners. • fMRI scans have higher spatial resolutions--AKA more clarity. • fMRI scans do not use radioactive dye like PET scans.

9. Advantages of fMRI Scans • Localizing brain activity during a task is easier w/ fMRI. • The time it takes to complete measurements is faster with fMRI scans. It takes only 1 to 2 minutes to scan most of the brain.

10. Limitations of fMRI Scans • We must consider ethical issues that come with gathering data as fMRI becomes more popular (we’ll discuss more later this week). Some concern over fMRI accuracy. FMRI measures blood flow changes during cognitive tasks- correlations between cognitive tasks and brain activity are not statements about causation.

11. Limitations of fMRI Scans Limits on accuracy continued… • Blood flow in the brain is fairly slow; starting about two seconds after neural activity starts. • Scans may not detect all neural activity. • Great skill is needed to design experiments using fMRI

12. Limitations of fMRI • There is concern that fMRI is not as legitimate or as justifiable as we might like to think. • fMRI scans may make it look like brain activity is more localized than it is in reality. • Although research as shown that it can correct these stereotypes (Hull and Vaid, 2006)

13. Limitations of fMRI • There is a lot of room for error when using fMRI based research-- Sometimes these images are over interpreted.

14. Examples of fMRI research: • Hull and Vaid (2006) • Berns et. al (2005) • Vorgan and Small (2002)

15. Examples of fMRI research: Conformity and the Brain • This study demonstrates how the biological and sociocultural levels of analysis interact (so we’ll talk about it more later). • A replication of Solomon Asch’s famous experiment + fMRI s

16. Solomon Asch’s Experiment • Solomon Asch (1955) wanted to study conformity and suggestibility. • He devised a simple experiment.

17. Asch’s Experiments on Conformity

18. Asch’s Experiments on Conformity

19. Results of Asch’s experiment? • Alone people only erred less than 1% of the time. • Within the group of confederates people erred 33% of the time. Influence resulting from one’s willingness to accept others’ opinions about reality.

20. Berns and colleagues (2005) • Many replications of Ash’s experiment exist. • Without scanning evidence, the mechanisms of conformity remain a mystery. • The question remains: Is conformity a decision-making process or does the group actually modify perceptions?

21. Berns et al (2005) • Hypothesis: • “If conformity resulted from conscious decision making, this would be associated with functional changes in the prefrontal cortex, whereas if social conformity was more perceptually based, then activity changes would be seen in the occipital and parietal regions.”

22. Berns et al. (2005) • Participants • 33 normal, right-handed participants • 14 males and 19 females • M age 26 • Method • Deception was used: Participants did not know that two male and two female actors were hired to give wrong answers.

23. Berns et al. (2005) • Procedures • Each participant was shown into a waiting room. • Every time a new participant entered the waiting room, the actors arrived in a haphazard way. • Participants and confederates then practiced the task 20 times on computers. • Pictures were taken of both the participants and the confederates so that when inside the fMRI scanner, participants could match the responses with the correct person.

24. Berns et al. (2005) • Procedures • The task was to decide if pairs of abstract 3-dimensional figures were the same. • Participants were told that others would know their answers. • Each participant was placed in an fMRI scanner and the trials began.

25. Berns et al. (2005) • Procedures • Phase 1: 48 trials with the group (three conditions: baseline, incorrect, correct). • Phase 2: 48 trials with the computer (same conditions) • Conformity was operationally defined as going along with incorrect information either from the group, or from the computer.

26. Berns et al. (2005) • Results • Participants judged the accuracy of the group and the computer to be about equal, 65.1% and 61.2% • Participants conformed to incorrect information from both sources (slightly more in social pressure group). • Baseline error rates averaged 13.8% and increased to 41% for the social pressure groups incorrect answers.

27. Berns et. al (2005) • Results (fMRI) • Baseline trials, where participants made their own choices, showed activity in the frontal cortex, occipital cortex, and parietal cortex. • The same brain regions were affected during social conformity. • Different brain regions were affected when subjects conformed to the computer. • When acting independently (going against the group) the right amygdala and right caudate nucleus are activated.

28. Berns et al (2005) • Conclusions • Social conformity related more to perception than decision making. • Changes in the visual cortex regions occurred when participants started to conform. • Limitations/Future Research • Needs to be replicated. • Problems with social desirability with a group of peers. • Future studies should examine the appeal of the group members to participants.