Biological Approach (SL)

What is the biological approach?

The biological approach to studying behaviour argues that there are physiological origins of many behaviours, and that human beings should also be studied in terms of their biology. Psychologists study how environmental factors interact with biological systems in both animals and humans. 

What are brain imaging techniques?

Brain imaging techniques is a term which covers a range of different methods used to produce images of the brain.

What are the 2 types of brain imaging technologies?

• Structural: showing the structure of the brain. 

• Functional: showing the activity of different parts of the brain.

What are 2 important concepts with brain imaging technologies that affect one’s ability to understand the brain?

• spatial resolution: refers to the resolution of the picture produced, therefore tells you exactly which area of the brain is active

• temporal resolution: how long it takes to take a frame - so how accurately changes in the brain can be tracked. It tells you exactly when the activation happened

What are the different parts of the brain stem?

• Medulla: heart rate, blood pressure and respiration. 

• Pons: sleep

• Mesencephalon: sex and aggression

What are the different parts of the limbic system?

• Corpus callosum: nerve fibers that connect the left and right  side of the brain

• Amygdala: responsible for sensing danger (“spidey sense”)

• Hippocampus: conscious memory

What is the cerebellum?

The cerebellum allows our motor behavior to be graceful (the motor cortex work with the cerebellum).

What are the different lobes in the cerebrum?

• Occipital Lobe: visual processing

• Temporal Lobe: perceives sound (music, speech and language)

• Parietal Lobe: sensation on our body

• Frontal Lobe:  voluntary movement, expressive language and for managing cognitive function.

What is localization?

Localization refers to the notion that specific areas of the brain are responsible for specific behaviours. It assumes that specific areas an be correlated with specific thoughts, feelings, and behaviours.

What are some limitations to localization?

• localization can cause errors in analysis

• studies in localization can lead to reductionist arguments for behaviour causation

• a clear causative relationship between location and function can rarely be inferred

• reducing complex behaviours to purely biological factors is tempting to researchers because it ignores factors that are difficult to study

• it is often difficult to identify the area to which the activation corresponds because of poor image quality and the complexity of the area in question

• brain locations are human constructions that are not present in actuality because the brain is highly interconnected organ

What is neuroplasticity?

Neuroplasticity is the term used to describe the changes in neural pathways and synapses due to changes in behaviour, environment, thinking, emotions, as well as changes resulting from bodily injury.

How is the density of neural connections increased?

High levels of stimulation and numerous learning opportunities lead to an increase in the density of neural connections. This means that the brain of an expert musician should have a thicker area in the cortex related to mastery of music when compared to the brain of a non-musician. Synapses become stronger through repeated use.  This is known as long-term potentiation.

What is dendritic branching?

Every time we learn something new, the neurons connect to create a new trace in the brain. This is called dendritic branching because the dendrites of the neurons grow in numbers and connect with other neurons.

What is the grey matter in your brain?

Gray matter is home to neuronal cell bodies, axon terminals, and dendrites, as well as all nerve synapses. Conducts, processes, and send information to various parts of the body. Allows enables individuals to control movement, memory, and emotions.

What is the white matter in your brain?

The white matter of your brain is composed of bundles of axons. Interprets sensory information from parts of the body. White matter's job is to conduct, process, and send nerve signals up and down the spinal cord.

What is neural pruning?

When a synapse is not used or is under-stimulated, it may go through the process of synaptic pruning. It is believed that this is the way for the brain to remove synapses that are no longer needed, making the functioning of the neural networks more efficient. The process of pruning is still not fully understood.

What are the basic functions of a neuron?

1. Receive signals (or information).

2. Integrate incoming signals (to determine whether or not the information should be passed along).

3. Communicate signals to target cells (other neurons or muscles or glands).

What do dendrites do?

They receive and process incoming information taking place in the dendrites and cell body.

What are the different types of signals that dendrites might be able to receive?

Incoming signals can be either excitatory – which means they tend to make the neuron fire (generate an electrical impulse) – or inhibitory – which means that they tend to keep the neuron from firing.

How does a neuron know when to fire?

Whether or not a neuron is excited into firing an impulse depends on the sum of all of the excitatory and inhibitory signals it receives. If the neuron does end up firing, the nerve impulse, or action potential, is conducted down the axon

What are synapses?

• Neuron-to-neuron connections are made onto the dendrites and cell bodies of other neurons - Synapse

• Synapses, are the sites at which information is carried from the presynaptic neuron, to the postsynaptic neuron.

What is neurotransmission?

• Neurons communicate with one another at junctions called synapses. At a synapse, one neuron sends a message to a target neuron—another cell.

• Most synapses are chemical; these synapses communicate using chemical messengers. An action potential triggers the presynaptic neuron to release neurotransmitters. These molecules bind to receptors on the postsynaptic cell and make it more or less likely to fire an action potential.

• Other synapses are electrical; in these synapses, ions flow directly between cells.

What is an excitatory neurotransmitter?

Excitatory neurotransmitters increase the likelihood of a neuron firing by depolarizing the neuron (membrane potential becomes less negative, opening the channel).  Excitatory neurotransmitters include acetylcholine.

What is an inhibitory neurotransmitter?

Inhibitory neurotransmitters decrease the likelihood of a neuron firing by hyperpolarizing the neuron (membrane potential becomes more negative, closing the channel). Inhibitory neurotransmitters include GABA.

What is a metabotropic neurotransmitter?

Metabotropic neurotransmitters only indirectly affect the neuron and are considered neither excitatory or inhibitory. Metabotropic neurotransmitters include serotonin, dopamine, and norepinephrine.

What are agonists?

Agonists are substances that bind to synaptic receptors and increase the effect of the neurotransmitter.

• All neurotransmitters are agonists for receptor sites.  

• Drugs can also be agonists.  For example, nicotine is an agonist for ACh receptor sites and in the short term appears to have some positive effects on memory. (It should be noted, however, that long-term use of nicotine has a negative effect on memory!)

What are antagonists?

Antagonists also bind to synaptic receptors but they decrease the effect of the neurotransmitter.

• Drugs that block the receptor site and do not allow the neurotransmitter to do its job, so no action potential is sent down the neuron. For example, scopolamine is an antagonist for ACh.

What are some strengths with neurotransmission theories?

• One of the key strengths is that they have led to successful treatments for certain behaviours. Successful drug treatments have been developed for psychological disorders.

• There is experimental research that supports the role of neurotransmitters in behaviour. These experiments can be replicated to establish reliability.

What are some limitations with neurotransmission studies?

• Research on neurotransmission can only be done indirectly. Reliance on fMRI technology means that the limitations of such techniques are relevant to the evaluation of many studies of neurotransmission.

• However, many of these studies are on animals. This means that we cannot guarantee that the neurotransmitter plays the same role in human behaviour.

• Much of the research on humans in correlational in nature. This means that we cannot establish a cause and effect relationship. For example, in the case of depression, bidirectional ambiguity is a problem. We do not know if a deficit in dopamine and serotonin causes depression or whether these deficits are a result of depression.

• The argument that neurotransmitters are the cause of behaviour is reductionist. Although a reductionist argument may be good in the study of memory since such arguments could potentially lead to positive strategies for helping people with memory impairment, explaining a complex behaviour like falling in love as a "neurochemical cocktail" could be considered an oversimplification of human behaviour.

What is the sympathetic nervous system?

It’s the part of the nervous system that responds to stress. It directs all the energy to the brain and heart during those stressful times to make sure you are out of danger first.

What is the difference between neurotransmitters and hormones?

Neurotransmitters are released from a neuron and travel across a synapse. Hormones are secreted by a gland into the bloodstream for more widespread distribution.

What is adrenaline?

Adrenaline is a hormone produced and released by the adrenal glands which activates the sympathetic nervous system.

What is cortisol?

Cortisol is produced in the adrenal glands. It functions to increase the amount of glucose (sugar) in the blood and to increase metabolism of fats, proteins, and carbohydrates. It provides the energy that is an important part of the “fight or flight response”.

How does adrenaline affect memory?

Adrenaline appears to play a role in the creation of flashbulb memories.

How does cortisol affect memory?

Cortisol appears to play a role in hippocampal impairment. We know that long-term exposure to cortisol leads to hippocampal atrophication as a result of hippocampal cell death.

What is a beta-blocker?

A beta-blocker is a drug used to treat heart disease because they target cells for the hormone so that the heart will pump more slowly and more efficiently. It prevents the activation of the amygdala.

What is oxytocin?

• Oxytocin has been labelled the 'love hormone', 'cuddle hormone', and 'trust hormone'. 

• It has been linked to:

  • animal therapy 

  • sexual health

  • is used to explain the bond between mother and child

  • important for social bonding (increases trust, affection, cooperation) 

• Oxytocin is produced in the hypothalamus and secreted by the pituitary gland. One of oxytocin's main functions is to prepare a pregnant woman for childbirth and breastfeeding, as it is increased at times of labour and lactation.

What is evolutionary psychology?

Evolutionary psychology is a theoretical approach that assumes human

thoughts, feelings, and behaviours have been subjected to evolutionary pressures.

What is natural selection?

Natural Selection: Those members of a species who have characteristics which are better suited to the environment will be more likely to breed, and this pass on these trails.

What is sexual selection?

Sexual Selection: a facet of natural selection, sexual selection is how the “best mate” is chosen to produce and protect the most healthy offspring.

What is intrasexual selection?

Intrasexual Selection: Competition between one sex (usually male) for access to mates. Usually the ‘strongest’ ends up being able to pass on his genes.

What is intersexual selection?

Intersexual Selection: Members of one sex (usually female) choose members of another sex based on specific characteristics – e.g. a dance, great feathers or, an amazing jawline.

What is the parental investment theory?

The parental investment theory argues that natural selection can account for sex differences in infidelity. The theory postulates that women, who typically invest more time and energy into raising their offspring, are more choosy when it comes to mate selection.  Women are looking for a partner who has the resources - both physical and material - that will protect their offspring. Men, however, have less parental investment. They are more interested in simply increasing their chance of spreading their DNA. This means that the more sexual activity that they have, the greater the chance of reproduction.

How is disgust and evolution related?

If people wrinkle up their faces at the sight of pustulent wounds or rotting food, then they have a better chance of avoiding deadly illness or food poisoning. Therefore, disgust may have evolved to protect people from poisoning themselves or eating harmful substances.

What are some limitations of evolutionary theories?

• Evolutionary theories are based on the assumption that behaviours are inherited. It is difficult to know that extent of which certain behaviours are in fact genetically inherited. There is usually not a single gene, but a combination of genetic coding which may lead to certain behaviours.

• It is difficult to test empirically – based on theories. Therefore, researchers may be susceptible to confirmation bias. 

• Much of the research to test the theories are highly artificial and lack ecological validity.

• Although we see similar behaviours in animals, it is debatable wo what extent we can generalize from animals and humans. 

• Underestimate the role of cultural influences and leaning in shaping behaviour. Many critics have pointed out that many traits considered universal by evolutionary psychologists may be be dependent on cultural and particular historical circumstances

• Assumes that the core reason of relationships is sexual reproduction – does not explain all love relationships.

• Studies do not establish cause and effect, but are overly descriptive in nature. They are correlational in nature and often seem to make the behaviour fit the theory.

What is a pheromone?

A pheromone is a chemical substance produced and released into the environment by an animal affecting the behaviour or physiology of others of its own species.

Do humans have pheremones?

• It is not agreed that there even are pheromones in humans (perfume companies believe that sent does have an influence). 

• Many of the examples of research have been challenged - either for their reliability or for the definition of a "pheromone."  

• Many of the claims of pheromones are not about behaviour, but about physiological processes, such as menstruation.

What theoretical evidence is there to support the role of pheromones in human behaviour?

Darwin reasoned the evolution of specialized odour glands in male mammals is “intelligible through sexual selection, if the most odiferous males are the most successful in winning the females, and in leaving offspring to inherit their gradually perfected glands and odours”. In common with other mammals, humans show changes in gland development as they move toward sexual maturity via the processes associated with puberty. Other mammals have been found to have chemicals they use as pheromones in common with humans.

What empirical evidence is available to support the role of pheromones on human behaviour?

20 different stimuli pairs were tested for a total of 260 mixture discrimination tests. Through computer programs, the researchers calculated that humans can discriminate at least 1 trillion olfactory stimuli, suggesting humans have evolved to be highly effective smellers. Wedekind et al concluded that people are motivated to find a mate with different immune system genes so their offspring will have a stronger immune systems. It can be concluded that body odour is an important element of human sociosexual behaviour.

What are alleles?

Alleles are different versions or forms of a gene that can exist at a specific location (locus) on a chromosome. Each individual has two alleles for each gene—one inherited from their mother and one from their father.

What does the length of an allele tell us?

The length of an allele may affect how much of a particular protein is produced. For instance, a longer allele might lead to more protein being produced, or it could potentially lead to the protein being less effective or functional.

What is the diathesis stress model?

The Diathesis-Stress Model of abnormal behaviour argues that psychological disorders are the result genes that are expressed as a result of environmental stressors. The most significant of these stressors are called ACEs - Adverse Childhood Experiences.

What are the limitations of using twin and adoption studies?

• Family studies are often based on anecdotal data - that is, asking family members about the behaviour of other members of the family.  In some cases, behaviour may be documented - for example, a diagnosis of bipolar disorder.  However, often this is not the case, so reports of one's sexuality, memory capacity or intelligence may be based on family stories, rather than on actual data.

• Twins do not represent the general population, so the research may not be generalizable. For example, there may be genetic factors that lead to higher rates of twins in some women.  In addition, twins are raised with someone that looks just like them and shares their experiences.

• DZ twins reared together may not share the same experiences due to levels of attractiveness or temperament.

• Most of the twin registry databases from which samples are drawn are from the developed world. The most commonly used are in Sweden, Denmark, Norway, Finland, Australia, the USA, and the United Kingdom. The Sri Lankan Twin registry, established in 1996, is the only existing population-based Twin Registry in a low-income country.

What are the strengths of using adoption studies?

• Adoption studies allow us to compare a child to their biological and adoptive parents.  If their behaviour is more similar to their biological than their adoptive parents, this indicates a possible genetic root of the behaviour.

• Adoption studies allow researchers to isolate variables by separating genetic (biological) influences from environmental influences, enabling them to distinguish the effects of biology versus environment on behavior or traits. 

• If a biological mother has no contact since birth and still matches for a specific trait - for example, the adopted child’s IQ is better than the adoptive mother and in concordance with the birth mother - this is strong evidence that genes play a significant role in the development of this trait.

What are the limitations of using adoption studies?

• Selective placement is a problem. Babies tend to placed with families similar in background to the biological parents.

• Adopted children – as well as twins - are not representative of all children. 

• The act of being given up for adoption may affect the child’s behaviour.

• Children that know that they are adopted are not representative of the general population.

• A large amount of adoption research focuses on the behaviour of the birth mother, rather than on the father.

• MZ twins are rarely separated at birth and raised in a totally different environment, yet this is really necessary to substantiate claims.