IB Psychology/Perspectives/Biological

Learning Outcomes for the Biological Level of AnalysisEdit

  • Outline biological principles. Explain how these principles are shown in research, describe why certain research methods are used and the ethical implications of these methodologies.
    • Behavior can be innate because it is based on genes.
      • Twin studies allow researchers to distinguish between nature and nurture influences on psychology. Bouchard did a study using monozygotic twins reared together or apart and found that twins were as similar regardless of whether they grew up together. This shows that genes contribute more to behavior than environment.
      • Twin studies are often used because genes and environment cannot be manipulated by researchers. Also, case studies are used because genes and environment can’t be manipulated, and it is unethical to purposely destroy part of a human brain. Thus, cases where this happens must be used as natural experiments.
        • An ethical concern with this research is that reuniting twins who have been separated or contacting families could harm the people involved. Also, there could be privacy issues with looking through courts records of adoptions.
    • Animal research can provide insight into human psychology.
      • James Olds used rats to determine the effects of stimulating the pleasure center of the brain. He found that rats would press a lever stimulating that center over and over to the exclusion of other needs such as eating. Because a parallel structure exists in human brains, this research has been generalized to humans.
        • An ethical concern related to animal studies is whether or not it is ethical to destroy parts of their brains or sacrifice them for autopsies in order to learn more about human psychology. For example, sacrificing rats to determine the effects of learning on the cortex.
    • Behavior is based on physiology.
      • Destruction of the hippocampus leads to amnesia. This is shown by the case study of Clive Wearing, whose hippocampi were destroyed by encephalitis. He is unable to form new memories following the loss. He can remember emotional things, however, since emotional memory appears to be stored in another structure.
        • An ethical concern is maintaining the privacy of the individuals being studied, like Clive Wearing.


  • Explain a study related to localization of brain function.
    • James Olds used electrodes to stimulate what he thought was the pleasure center of the brains of rats. When allowed to stimulate themselves, Olds found that rats would do so to the exclusion of fulfilling other needs, like eating. This shows that pleasure (of all kinds, like eating and sex) is localized in a specific brain area.
OR

The very first time Sperry did his work on splitting brains was with cats and he discovered when the corpus callosum was severed, the two halves of the brain couldn’t transfer information to work together. Later, Roger Sperry did a split-brain operation on 10 patients who wish to relieve from severe epilepsy. Sperry began testing the functions of the each hemisphere. Experiments included showing images to only one hemisphere by asking patients to focus on a central point and flashing the image to the far left or right too quickly to allow the eyes to move. The conclusion is that both eyes send information to the brain about both halves of the visual field. Information from the left eye is sent to the right hemisphere of the brain and vice versa. Also, he discovered that the right brain is dominant in visual spatial ability, as well as musical abilities and understanding intonation in speech. The left half is dominant in language, logical or mathematical abilities.


  • Explain the effects of a neurotransmitter, with research.
    • A study done with Japanese monks and volunteers who meditated found that when the monks began hallucinating due to the meditation the levels of serotonin in their hypothalamuses and cortexes became elevated.
  • Explain the functions of two hormones, with research.
    • Melatonin controls the sleep cycle. For example, when traveling, melatonin cycles cause jet lag as the cycle does not catch up immediately to the body’s location.
    • Oxytocin is a hormone that causes bonding. It is released during physical contact and nursing.
  • Discuss the effects of environment on physiology.
    • Changes in location and light levels cause a disruption in the melatonin cycle that controls sleep. This leads to jet lag.
    • Famine causes women to stop menstruating because since there is not enough food to support a baby, the body shuts down the mechanisms that allow babies to be made.
  • Examine the interaction between cognition and physiology (brain and mind).
    • Amnesia can be caused by the destruction of the hippocampi.
      • Clive Wearing’s hippocampi were destroyed by illness, causing him to have anteretrograde amnesia.
      • Also, a subject named HM suffered damage to the hippocampi in an attempt to treat his epilepsy, causing him to suffer amnesia as well.
  • Discuss the use of brain imaging techniques in linking biology and behavior.
    • EEG scans allow the researcher to examine the electrical activity of the brain, isolating which areas are active during certain behaviors.
    • PET scans allow the researcher to looks at glucose metabolism in the brain. This can allow them to isolate abnormalities like tumors, which metabolize differently.
  • To what extent does genetic inheritance contribute to behavior?
    • 'Bouchard’s twin studies show that genetics contribute greatly to aspects of a person such as personality, intelligence, career and even things like divorce. These things are influenced more, it seems, by genes than by environment.


  • Examine one evolutionary explanation of behavior.
    • Male sexual promiscuity is explained by natural selection. Since men have low investment in each individual offspring, they have promiscuous sex in order to pass on their genes as much as possible. In contrast, since women invest for at least nine months in their children, they tend to be more monogamous.
  • Discuss ethical considerations of research into genetic basis’s for behavior.
    • The ethical implications of genetic research include the fact that knowing an individual’s predisposing for diseases with a genetic component could lead to discrimination in marriage, job opportunities, or even the provision of health insurance (since insurance companies would know that a person was likely to make claims due to their risk of disease).