Information Technology Reference
In-Depth Information
2.2 Materials
Videos that consisted of faces of four different individuals (two male, two female)
were used. The videos consist of face articulating a nonsense bi-syllable word (with-
out the audio track). Each of the stimuli was expressed by a kind of emotion valence:
happy, angry or neutral.
Mean duration of standard (non-target) stimuli is 1170 ms. There is no significant
difference among the three different emotional types of stimuli. Deviant stimuli were
inserted with a 200 ms interruption on the basic of the standard stimuli. All faces
covered a visual angle of about 3.4*4.9 degree.
2.3 Design and Procedure
This is a two-factor within-subject design. The experimental factors are spatial atten-
tion (attended/unattended) and emotion valence (angry/happy/ neutral).
Participants were seated in a dimly lit sound-attenuated room, with response but-
tons under their right hands. All stimuli were presented on a computer screen in front
of a black background at a viewing distance of 70cm. A cross maintained at the center
of the screen as the fixation. The eccentricity of the faces (measured as the distance
between the centre of each face and the central fixation cross) was 4.2 degree.
The experiments consist of six blocks, each containing 48 standard trials and 16
deviant trials. In each block, participants were asked to pay attention to only one side
(left or right) and respond to the deviants and standards as soon as possible. Forty-two
standards and six deviants were presented at the attended side in every block. In each
trial, an expression video was present at only one side of the screen with the central
fixation. The ISI varied from 1200ms to 1500ms.
3 Results
One participant's data are excluded due to the low accuracy (below 80%). Fourteen
available data were collected and analyzed. Considering the deviants with short inter-
ruption were artificially made and can not present the natural expressions, the re-
sponds to the deviant stimuli are excluded. Only the data of the standard stimuli are
analyzed and compared through different conditions. Repeated Measure ANOVAs
with two factors, facial emotion (angry, happy, neutral) and spatial attention were
carried out on percentage of accurate responses and reaction time, respectively.
3.1 Reaction Time
The reaction time from the onset of the stimulus to the respond was recorded. The
average of RT to all the stimuli is 1214.76ms.
The main effect of spatial attention is significant (
F
1, 13
= 12.506,
P
<0.01). The re-
sponds to the stimuli in the attended location is much faster than the responds to the
unattended stimuli.
RTs of emotional and neutral expressions are different. If we consider all the data
regardless the attention factor, the reaction to the emotional stimuli is faster than the
neutral stimuli but not significant (
F
2, 26
= 2.623,
P
=0.092). But Fig.1 shows the detail
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