sperry + casey

• SPERRY ET AL (1968) conducted a split brain study: Hemispheric disconnection and unity in consciousness
• Key theme of the study

  • Regions of the brain
• The study involved a split brain with one half atheist and one half theist
• True or false brain facts

  • Your brain is the fattiest organ in the body
  • Your brain is formed by the age of 20
  • Brain info travels at 150 mph
  • You only use 10% of your brain
  • Males brains weigh more than females
• Biological factors that affect our behaviour

  • Genetics
  • Brain structure
  • Brain chemistry
  • Nervous system
  • Hormones
  • DNA
• The case of Jeff Landrigan suggests that criminal behaviour may have a genetic predisposition
• The Nature vs Nurture debate in the case of Jeff Landrigan would suggest that supporters of the biological area believe criminal behaviour has a biological basis
• There could be other explanations for Jeff's actions besides just his genetics, such as environmental factors
• Reductionism

  Biological psychology is considered reductionist as it focuses on how simple factors like biology influence behaviour, rather than more complex factors
• Reductionism is often seen as a criticism, but it can also be seen as a strength as it is much easier to be scientific when we focus on how simple factors influence behaviour
• As biological psychology is very scientific, it is important to consider the debate around PSYCHOLOGY AS A SCIENCE
• Assumptions of biological psychology

  • Behaviour can be largely explained in terms of biology – genes, neuroanatomy, neurochemicals etc have a direct influence on behaviour
  • Psychology should be seen as a science, to be studied in a scientific manner (usually in a lab) measuring variables objectively, eg MRI scans
  • The biological approach focuses on how nature rather than nurture influences us
• The brain is divided into two hemispheres - the left and right hemispheres
• The corpus callosum is responsible for communicating messages from the left to the right hemisphere and vice versa
• The left hemisphere controls the right side of the body, and the right hemisphere controls the left side of the body
• The left visual field is controlled by the right hemisphere, and the right visual field is controlled by the left hemisphere
• Instructions for a task to determine visual fields

  1. Shut one eye

  2. Stare at something small in front of you

  3. Decide what else you can see to the left and right

  4. The area to the left is the left visual field, the area to the right is the right visual field

  5. Repeat with the other eye
• Information from both eyes goes to both hemispheres, so humans are cross-wired
• The left hemisphere is associated with language processing, while the right hemisphere is associated with drawing
• Epilepsy is caused by abnormal firing of electrical impulses throughout the brain which interrupts normal brain patterns
• During a seizure, electrical impulses pass from one hemisphere of the brain to the other
• A procedure called split brain surgery, which involves cutting the corpus callosum, can be used to stop the spread of electrical impulses between the hemispheres and stop seizures
• The aim of the Sperry et al. (1968) study was to test the effects of hemispheric disconnection in humans and investigate whether cognition differs between the hemispheres
• The study used a quasi-experimental research method and also included case studies of the individual patients
• The participants were 11 patients with epilepsy who had undergone a commissurotomy procedure to divide their brain by cutting or removing the corpus callosum
• Visual apparatus and procedure

  1. Participants had one eye covered and were asked to stare at a fixation point on a projector screen

  2. Information was flashed to either the left visual field or right visual field for 1/10th of a second

  3. Controls included the fixation point, image flash duration, eye coverage, and standard stimuli
• Tactile apparatus and procedure

  Below the screen was a gap so participants could be handed objects or reach into a 'grab bag' and touch objects but could not see the objects or their hands
• Participants remained in silence during trials unless asked a question by the experimenter
• Different tasks - Visual and Tactile

  • Recognising pictures
  • Matching pictures
  • $ and ?
  • Composite words
  • Identify objects in hand or find from grab bag
  • Dual processing task
• If a stimulus was flashed to the left side of the screen


  The participant did not recognise it when it was flashed to the right side, but did recognise it if it was flashed to the right side again
• If a picture was projected to the right visual field


  The participant could talk and write about it, but if the same picture was projected to the left visual field, the participant said they saw nothing or just a flash of light
• If the participant was asked to use their left hand to pick up a matching object from a grab bag


  They would pick up the object that they had just said they didn't see
• If a $ was flashed to the left visual field and a ? to the right visual field


  The participant would draw the $ using their left hand, but say they saw the ?
• When two words were flashed simultaneously to the left and right visual fields


  The participant could not integrate the words into a composite word
• Biological approach

  • Behaviour can be largely explained in terms of biology – genes, neuroanatomy, neurochemicals etc have a direct influence on behaviour
  • Psychology should be seen as a science, to be studied in a scientific manner (usually in a lab) measuring variables objectively, eg MRI scans
  • The biological approach focuses on how nature rather than nurture influences us
• Previous research by Eigsti (2006) showed that performance on a delay-gratification task in childhood predicted the efficiency with which the same individuals performed a cognitive task (go/nogo task) as adolescents/adults
• Those who as preschoolers directed their attention towards the rewarding aspect of the classic delay-of-gratification situation such as focusing on cookies/marshmallow (high temptation focus group) had more difficulty suppressing inappropriate actions than their low temptation counterparts
• These findings suggested that performance on cog control and the ability to control one's thoughts and actions can vary by the potency of interfering info
• Alluring or social context can diminish self control
• Delay of gratification


  An ability to put off something fun/pleasurable now in order to wait for something that is greatly fun/pleasurable or rewarding later