Positive EventRelated Potentials in a Social Stimulation Task

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Positive Event-Related Potentials in a Social
Stimulation Task

• Justin Dainer-Best
• Advisor R. Compton
• Haverford College

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EEG
Subjects wear a cap (above) that has
silver-chloride elecrodes on the top. Gel is
inserted into the cap via a syringe, while its
worn by the subjects. It is a noninvasive
procedure.
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The Late Positive Potential (LPP/P300)

• Event-Related Potentials (ERPs) are an
  electroencephalographic (EEG) technique through
  which subjects respond to a prompt and their
  brain reactions (in relation to the event) are
  recorded
• ERPs measure the electrical activity of a general
  regionnot of a specific area
• the difference from sites of interest and
  reference sites is computed
• LPP is found between 300 and 500 ms after image
  presentation
• It has been shown to be maximum at parietal
  midline locations on the scalp (Duncan-Johnson
  Donchin, 1977)
• Attentional orientingemotional stimuli elicit
  greater results (Schupp et al., 2006)
  task-relevant oddball stimuli do as well
  (Duncan-Johnson Donchin, 1977)

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Attachment Style

• What is attachment?
• Originally theorized by Bowlby the Strange
  Situation (Ainsworth, Blehar, Waters, Wall,
  1978) characterized infants by behavior towards
  their mothers
• Hazan and Shaver (1987) use the language of
  cognitive psychology to describe attachment
  processes, suggesting that infants and hence
  adults create internal working models of their
  relationships with their caregivers or romantic
  partners
• Bartholomew and Horowitz (1991) conceptualized
  four categories of attachment, using these two
  models, one along a continuum of emotional
  dependence and the other along a continuum of
  avoidance
• Here, measured by two questionnaires
• Experiences in Close Relationships Questionnaire,
  Revised
• Adult Attachment Questionnaire

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Attachment and EEG

• Zilber, Goldstein, and Mikulincer (2007) found
  that high attachment-anxiety participants had
  greater LPP amplitudes to negative pictures
  (attentional bias)
• Subjects categorized viewed images as neutral,
  pleasant, or unpleasant
• Subjects who were highly attachment-avoidant also
  showed highly positive LPPs

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Attachment and EEG

• Moser, Hajcak, Huppert, Foa, Simons (2008)
• low-anxious (NOT attachment) participants had
  more pronounced P600 amplitudes to an
  ambiguous-sentence task
• Suggested explanation low-anxious participants
  saw negative endings to sentences as unexpected
  and inconsistent with their interpretations of
  the sentences (interpretation bias)

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The Task

• A social stimulation task
• 2 types of trials (context)
• In-sequence images (two scene-setting images,
  then a target image)
• Solo images (just the target image)
• 4 types Images were either negative, positive,
  random, or neutral
• Images were drawn by Jacob Carroll 09 and
  Rebecca Morgan 10
• Images were presented in-order by block, but
  randomly within the block Rebecca, then Jacob,
  and so forth. In-sequence, then solo.
• Target images were presented until a response was
  registered subjects rated them based on how
  happy the character of their gender was, on a
  scale of 1-9.

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Hypotheses

• Considering the role of attachment-related
  anxiety in shaping attention to negative images
  and to attachment-relevant scenarios.

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Participants

• 40 subjects (24 female, 16 male), between the
  ages of 18 and 22.
• Filled out questionnaires before coming into lab
• Primarily right-handed, heterosexual, white
• All but three had relationship experience
• Screened for basic exclusionary criteria

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Results

• Behavioral data
• More thought involves in slower RTs
• In-sequence images had a slower RT
• Random images had a significantly slower RT than
  the others
• Images were rated as-expected
• Negative images were rated as low on the
  happiness scale
• Neutral and random images received middling
  ratings
• Positive images received high ratings

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Results
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Results
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Conclusions

• Can the data be explained by attachment or the
  anxiety variables?
• Primarily, no.
• The ECR-Rs avoidance subscale, when considered
  as a categorical variable
• High-attachment-avoidant subjects had more
  positive LPPs to negative images than
  low-avoidant subjects, in-sequence, but not when
  images were shown alone
• The rest of the sub-scales, and the anxiety
  scales, did not cause the data to covary.

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Conclusions

• Expectancy of attachment-related events did not
  influence the Late Positive PotentialLPP instead
  seemed to be influenced primarily by the
  emotionality of the images (as in Schupp et al.,
  2006 Zilber et al., 2007)
• Were the expectancy-responses too basic to be
  accessed by the task? Or were the emotional
  contexts too strong to allow for the responses?
• N400?
• Why were there no attachment-related findings?
• Perhaps these images are not yet accessing the
  schema that would cause such a modulation.
• Perhaps subjects did not adequately identify with
  the character in the drawings, and therefore did
  not use their own attachment schemas.