Selfrecognition in the two cerebral hemispheres Lucina Uddin1, Julian Keenan2, Eric Mooshagian1, Jan

1
Self-recognition in the two cerebral
hemispheresLucina Uddin1, Julian Keenan2, Eric
Mooshagian1, Jan Rayman1, and Eran Zaidel11
Department of Psychology, University of
California Los Angeles, Los Angeles, CA.2
Department of Psychology, Montclair State
University, Upper Montclair, NJ.
780.1
Data Analysis
Introduction
Discussion
We used signal detection methods to compute d'
as a measure of sensitivity of detection of
self or friend stimuli. Images morphed
towards other more than 50 were designated as
target-absent trials. A response was considered
a target-present response if the subject
responded self in the self block or friend in
the friend block. We also analyzed the natural
log of beta, a measure of subjects response bias
independent of sensitivity. Each of these
measures was subjected to an ANOVA.
Hemispheric specialization for self-face
recognition is still unclear. Some recent
studies have suggested that the right prefrontal
cortex of the human brain is concerned with
processing images of the self and, more
generally, with self concept. However, some of
these reports have presumed that responses with
the right or left hand are sufficient to reflect
contralateral hemispheric performance, and others
confused discrimination with response strategy.
In this study, we used signal detection measures
to look at sensitivity and bias. Tachistoscopic
presentation was used to present morphed
self-face images randomly to the right or left
visual field (VF) in order to assess more
rigorously the lateralization of self concept in
the normal brain.

• Normal subjects exhibit left hemisphere
  specialization for discriminating friend but
  both hemispheres are equal at discriminating
  self.
• The left hemisphere has a greater bias than the
  right hemisphere to respond self.
• Lateralized responses do not parallel
  lateralized targets left hand responses are more
  sensitive to friend than to self.

Methods
Conclusions

• Participants 32 right-handed UCLA
  undergraduates.
• Stimuli images morphed to different extents
  (0-100, 5 increments) between the subject and
  an unknown, gender-matched face (self condition)
  and morphs between the subjects friend and an
  unknown, gender-matched face (familiar friend
  condition).
• Task subjects responded unimanually and were
  instructed to press one button on a response box
  if the image presented looked more like an image
  of self (familiar friend), and another if the
  image looked more like an unknown other face.

• The left hemisphere shows increased sensitivity
  to detect friend images and increased bias to
  self responses.
• For the self task, the VF difference expresses
  itself mainly in hemispheric differences in bias,
  whereas for the friend task, these differences
  show up in hemispheric differences in
  sensitivity.
• Self stimuli were processed by the hemisphere
  that initially received them (direct access). VF
  of target and response hand show different
  laterality effects, but only the former is a
  measure of hemispheric specialization for the
  cognitive aspects of the task.

• Significant Target Face x VF interaction, F(1,31)
  4.29, p 0.05

Examples of Stimuli (Self/Friend
Other)


References

• Target Face x VF interaction, F(1,31) 3.47, p
  0.07

• Keenan JP, Freund S, Hamilton RH, Ganis G,
  Pascual-Leone A. Hand response differences in a
  self-face identification task. Neuropsychologia
  2000 38 1047-53.
• Turk DJ, Heatherton TF, Kelley WM, Funnell MG,
  Gazzaniga MS, Macrae CN. Mike or me?
  Self-recognition in a split-brain patient. Nature
  Neuroscience 2002 Advance Online Publication.
• Zaidel E. On Measuring Hemispheric
  Specialization in Man. In B. Rybak, Ed.,
  Advanced Technobiology 1979 365-404.

0 Morph (Self/Friend)
50 Morph
100 Morph (Other)

Task Self or Other?

• Significant Response Hand x Target Face
  interaction, F(1,31) 5.18, p 0.03

180ms
Contact Lucina_at_ucla.edu