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An experiment with 42 human Ss used the transswitching procedure to examine tonic stimulus control of phasic and tonic conditioned vasomotor heart rate, and electrodermal reactions. The conditional stimulus (CSs) were photos of angry and friendly human faces, and the unconditional stimulus (US) was a human scream. In one tonic context (blue light), the CSs were paired with the US, in the other context (yellow light), the CSs were presented unpaired. Following acquisition, an extinction series was run with the US omitted during both tonic contexts. Phasic vasomotor and skin conductance reactions differed in the positive and negative tonic segments (stronger in positive). The skin conductance responses also differed during extinction, but the vasomotor responses did not. Tonic differences (following onset of the tonic stimuli) in unelicited skin conductance response frequency, finger pulse volume, and heart rate were also found, although these developed more slowly than the phasic differences. The finger pulse volume tonic difference was greater in extinction than the skin conductance response frequency. There was no effect of the angry-friendly facial expressions, either directly or in interaction with the transswitching effects. The results were interpreted to mean that the transswitching phenomenon is not limited to one another autonomic effector, but is more generalized across the ANS (sympathetic branch). The absence of influence of the facial expressions indicates the relative weakness of the "preparedness" hypothesis in comparison with more influential contextual factors.
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fMRI studies have shown that the perception of facial disgust expressions specifically activates the insula. The present fMRI study investigated whether this structure is also involved in the processing of visual stimuli depicting non-mimic disgust elicitors compared to fear-inducing and neutral scenes. Twelve female subjects were scanned while viewing alternating blocks of 40 disgust-inducing, 40 fear-inducing and 40 affectively neutral pictures, shown for 1.5 s each. Afterwards, affective ratings were assessed. The disgust pictures, rated as highly repulsive, induced activation in the insula, the amygdala, the orbitofrontal and occipito-temporal cortex. Since during the fear condition the insula was also involved, our findings do not fit the idea of the insula as a specific disgust processor.
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fMRI studies have shown that the perception of facial disgust expressions specifically activates the insula. The present fMRI study investigated whether this structure is also involved in the processing of visual stimuli depicting non-mimic disgust elicitors compared to fear-inducing and neutral scenes. Twelve female subjects were scanned while viewing alternating blocks of 40 disgust-inducing, 40 fear-inducing and 40 affectively neutral pictures, shown for 1.5 s each. Afterwards, affective ratings were assessed. The disgust pictures, rated as highly repulsive, induced activation in the insula, the amygdala, the orbitofrontal and occipito-temporal cortex. Since during the fear condition the insula was also involved, our findings do not fit the idea of the insula as a specific disgust processor.
Erkunden
Eintragsart
Sprache
- Englisch (3)
Thema
- Facial Expression
- Adult (3)
- Amygdala (2)
- Anger (1)
- Cerebral Cortex (2)
- Conditioning, Psychological (1)
- Emotions (2)
- Extinction, Psychological (1)
- Fear (2)
- Female (3)
- Frontal Lobe (2)
- Habituation, Psychophysiologic (1)
- Heart Rate (1)
- Humans (3)
- Magnetic Resonance Imaging (2)
- Male (1)
- Occipital Lobe (2)
- Pattern Recognition, Visual (2)
- Skin (1)
- Smiling (1)
- Temporal Lobe (2)
- Vasoconstriction (1)
- Visual Perception (2)