1. Phobia – Biological Theories The anxiety response in phobia involves the same structures & processes responsible for the stress response Some researchers suspect that phobia involves abnormalities in these structures & processes www.psychlotron.org.uk

2. NS Reactivity Liebowitz et al (1985) –Gave social phobics and controls air with increased CO 2 content to stress them –Social phobics panicked significantly more often than controls These and many similar results suggest that some types of phobia involve hyper- reactivity of the sympathetic NS www.psychlotron.org.uk

3. Amygdala Abnormalities Part of the limbic system Involved in processing of fear & startle stimuli Source: Hairiri et al, 2002Amygdala www.psychlotron.org.uk

4. Amygdala Abnormalities Pine (1999) –Compared amygdala responsiveness in social phobics and normal controls –Found that social phobics had more responsive amygdalae Suggests that phobics may be more susceptible to fear-evoking stimuli www.psychlotron.org.uk

5. Amygdala Abnormalities Hariri et al (2002) –Compared PPs with different types of 5HT receptors –Examined right amygdala responses to angry/fearful faces –Abnormal receptor group were significantly more responsive Source: Hairiri et al, 2002 www.psychlotron.org.uk

6. Conclusions Genetic research suggests that phobia susceptibility may be inherited Some phobias appear more heritable than others (e.g. blood-injury; social) Some phobias (esp. social) may be linked to abnormally responsive sympathetic NS and hyper-reactivity to fearful stimuli www.psychlotron.org.uk