Transcript No Slide Title

Evoked Response Potential (ERP)
and Face Stimuli
• N170: negativegoing potential at
170 ms
• Largest over the
right parietal lobe,
also on the left
parietal lobe.
From Tanaka and Curran (2001)
An Experiment
• Show Faces and Words Embedded in
Noise:
High
Contrast
Faces
Low
Contrast
Faces
Noise
Alone
Low
Contrast
Words
High
Contrast
Words
The Important Stuff:
RightNoise-Alone
Temporal LobeTrials:
(T6)
For
* t(9) = 2.74,
p = .023
Amplitude (V)
4
2
0
*
-2
High
Contrast
Faces
Low
Contrast
Faces
Noise
Alone
Low
Contrast
Words
High
Contrast
Words
-4
Responded 'Word' T o Noise-Alone T rial
Responded 'Face' T o Noise-Alone T rial
0
100
200
300
time (ms)
400
500
600
Main Result:
• On noise-alone trials: Larger N170 when observers report
seeing a face than when report seeing a word.
• Occurs in 9 of the 10 subjects.
• No other differences in any other channel at the P100, N170
or P300 components.
• Unlikely to just reflect activity for an already-made decision.
• Relates activity in the perceptual processing areas to the
behavioral response. Greater activity in the N170 neurons is
associated with ‘face’ responses to the noise-alone stimulus.
One interpretation: Greater activity in the face processing region
biases the response towards a ‘face’ response.