Biological exps of phobias

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  • Biological explanations of phobias
    • Genetics
      • View that we inherit genetic predisposition to become anxious
      • Research uses family and twin studies to asses what role genetics play
        • MZ = identical
          • Same genes
        • DZ = unidentical
          • Only 50% same genes
        • FAMILY
          • Lautch (1971)
            • Fear of dentist runs in family
          • Noyes et al (1986)
            • High incidence of agoraphobia in 1st degree relatives
          • Ost (1992)
            • 64% blood/injection phobics had 1st deg relative with phobia too, comapred to 3% rate in general population
        • TWINS
          • Torgersen (1983)
            • Panic disorder and agoraphobia. 31% concordance in 13 MZ twins
            • No concordance in 16 DZ twins
          • HOWEVER - Kendler et al (1992) found opposite
            • 722 female twins, history of agoraphobia
              • MZ twins significantly lower concordance rates than DZ
      • Commentary
        • Can't just be 100% genetic as concordance is never 100%
        • Not clear what exactly is passed on genetically
        • Other factors? E.g. shared environment
        • Family
          • Self report
            • Memory lapses
            • Distortations
            • Impress investigator
        • Twins
          • More reliable but few done
            • Adoption studies would be better
    • Biochemistry
      • Structural or biochemical abnormalities should be detectable in the brains of those with phobic disorders
      • GABA = neurotransmitter, main inhibitory chemical in nervous system
        • Reduces stress and anxiety
          • Phobia could be caused by reduction of GABA
      • Amygdala = part of brain that is activated in response to threat
      • Applegate et al (1982)
        • Studies show that when you pair aversive stimulus with neutral stimulus, neurons fire in amygdala
      • Kemble et al (1990)
        • When amygdala is deliberatley damaged in animal studies, they show a reduction in innate fears
          • Applegate
            • Conditioned fears also
      • Commentary
        • :)
          • Treatment with drugs successful
            • Treatment mimics GABA
            • Drug effects are short term
        • :(
          • Drug effects are short term
          • Effects only slightly better than placebo in kids
          • Use of animal studies?
          • Blood flow abnormalities - Causal factor or result of phobic disorder?
    • Evolutionary
      • "Innate biological memory"
      • Fact phobias still apparent suggests evolutionary
      • If phobias had no purpose, natural selection would have selected them out
      • Research
        • Rakinson (2000)
          • 11 month old girls learned quicker than boys to associate negative facial emotions with snakes and spiders
            • No gender diff for fear irrelevant objects
              • Suggesting evol theory - 4 times as many females have snake/spider phobia
                • They more likely to encounter them while foraging in old times
        • Cook and Mineka (1989)
          • Demo'd to lab raised monkeys fear response to toy snake and rabbit
            • They then showed similar fear to snake but not rabbit
              • Suggests evol readiness to fear snakes but not rabbits
        • Commentary
          • :)
            • Explains for dangerous stimuli
              • Learned helplessness explains why harder to develop fear of dangerous modern day things
                • E.g. guns, weren't around before evolution
            • Good explaining how easy can be developed e.g. Ohman
          • :(
            • Some phobias so bizarre and individual
              • Best explained as conditioned not evol
            • Deterministic, doesn't account for individual/cultural diffs
            • Davey (2004)
              • Not evol fear of snakes and spiders but evol disgust
                • Linked to disease
            • Ohman - were developing phobia or just afraid of shocks?
  • Ohman et al (1975)
    • Research
      • Rakinson (2000)
        • 11 month old girls learned quicker than boys to associate negative facial emotions with snakes and spiders
          • No gender diff for fear irrelevant objects
            • Suggesting evol theory - 4 times as many females have snake/spider phobia
              • They more likely to encounter them while foraging in old times
      • Cook and Mineka (1989)
        • Demo'd to lab raised monkeys fear response to toy snake and rabbit
          • They then showed similar fear to snake but not rabbit
            • Suggests evol readiness to fear snakes but not rabbits
      • Commentary
        • :)
          • Explains for dangerous stimuli
            • Learned helplessness explains why harder to develop fear of dangerous modern day things
              • E.g. guns, weren't around before evolution
          • Good explaining how easy can be developed e.g. Ohman
        • :(
          • Some phobias so bizarre and individual
            • Best explained as conditioned not evol
          • Deterministic, doesn't account for individual/cultural diffs
          • Davey (2004)
            • Not evol fear of snakes and spiders but evol disgust
              • Linked to disease
          • Ohman - were developing phobia or just afraid of shocks?
    • Paired pics with electric shocks, either harmful or not
      • 5 times longer for people to show fear response to harmless pics

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