Chapter1.ppt psych 2

Chapter 1The Major Issues

The Mind-Brain Relationship

• Biological Psychology is the study of the physiological, evolutionary and developmental mechanisms of behavior and experience.

• A strong emphasis is placed upon brain functioning.


• Brain functioning can be explained at a more microscopic level in terms of neuron and glia activity.


• Biological explanations of behavior fall into four categories:– Physiological-relates a behavior to the

activity of the brain and other organs.– Ontogenetic- describes the development of

a structure or behavior.– Evolutionary- reconstructs evolutionary

history of a behavior or studcutr4.– Functional- describes why a structure or

behavior evolved as it did.


• Deep understanding of a particular behavior is tied to being able to explain the behavior from each of these perspectives.


• Biological explanations of behavior raise the issue of the relationship between the mind and the brain also know as the “mind-body” or “mind-brain problem”.

• The “mind-brain problem” has a variety of explanations.


• Dualism is the belief that there are different kinds of substance that exist independently.– Defended by French philosopher Rene

Descartes.– Most common belief among nonscientists.– Rejected by most neuroscientists.


• Monism is the belief that the universe is only comprised of one type of substance.

• Forms of monism include:– Materialism- everything that exists is

physical by nature.– Mentalism- only the mind truly exists.– Identity position- mental processes and

some brain processes are the same but described in different terms.


• Explanations of the mind-body relationship do not answer some fundamental questions:– Why is consciousness a property of brain

activity?– What kind of brain activity produces

consciousness?– How does brain activity produce

consciousness?


• Because “consciousness” is not observable, its function is often difficult to define and/ or explain.

• Solipsism- suggests that “I alone am conscious”– Difficulty of knowing if others have

conscious experiences is known as the “problem of other minds”.


• Chalmers (1995) proposes two problems that must be distinguished when discussing consciousness:

– “Easy problems” focus on differences in conscious states and their mechanisms.

– “Hard problems” focus on why and how brain activity is associated with consciousness.


• Careers related to biological psychology fall into two categories:

1. Research

2. Therapy


• Insert table 1.1 Fields of specialization

The Genetics of Behavior

• Both genes and environment interact to shape human behavior.

• The fundamental issue is how much a role genetics play in shaping human behaviors.– Examples: psychological disorders, weight

gain, personality, sexual orientation?


• 19th century monk Gregor Mendel demonstrated that inheritance occurs through genes.

• Genes are basic units of heredity that maintain their structural identity from one generation to another.

• Genes are aligned along chromosomes (strands of genes) and come in pairs.


• A gene is a portion of a chromosome and is composed of deoxyribonucleic acid (DNA).

• DNA serves as a model for the synthesis of ribonucleic acid (RNA).


• RNA is a single strand chemical that can serve as a template/ model for the synthesis of proteins.

• Proteins determine the development of the body by:• forming part of the structure of the body.• serving as enzymes, biological catalysts

that regulate chemical reactions in the body.


• Homozygous for a gene means that a person has an identical pair of genes on the two chromosomes.

• Heterozygous for a gene means that a person has an unmatched pair of genes on the two chromosomes.


• Genes are either dominant, recessive, or intermediate.

– Examples: eye color, ability to taste PTC• A dominant gene shows a strong effect in

either the homozygous or heterozygous condition.

• A recessive gene shows its effect only in the homozygous condition.


• Types of genes include:– Autosomal genes - all other genes except

for sex- linked genes.– Sex-linked genes - genes located on the

sex chromosomes.• In mammals, the sex chromosomes are

designated X & Y. – Females have two X chromosomes (XX).– Males have an X and a Y chromosome

(XY).


• During reproduction:– Females contribute an X chromosome.– Males contribute either an X or a Y

chromosome that determines the sex of the child.

• If an X chromosome is contributed by the male, the off-spring is female.

• If a Y chromosome is contributed by the male, the off-spring will be male.


• The human Y chromosome has genes for 27 proteins

• The human X chromosome has genes for approximately 1500 proteins.

• Thus, sex-linked genes usually refer to X-linked genes. (Example: Red-green color deficiency)

• Sex-limited genes are genes that are present in both sexes but mainly have an effect on one sex (Chest hair, breast size, etc.)


• Almost all behaviors have both a genetic component and an environmental component.

• Researchers study monozygotic (“from one egg”) and fraternal (“from two eggs”) twins to infer contributions of heredity and environment

• Researchers also study adopted children and their resemblance to their biological parents to infer hereditary influences.

• Heritability refers to how much characteristics depend on genetic differences.

• Estimates of hereditary influences are often difficult to infer and are prone to error.

• Sources of error include the following:– The inability to distinguish between the

effects of genes and prenatal influences.– Environmental factors can inactivate

genes.


• Sources of error (con’t)– Multiplier effect – genetic tendencies that

guide behavior will result in a change in the environment that magnifies the original tendency.

– Traits with a strong hereditary influence can by modified by environmental intervention.• Eg. PKU


• Genes do not directly produce behaviors.• Genes produce proteins that increase the

probability that a behavior will develop under certain circumstances.

• Genes can also have an indirect affect.– Genes can alter your environment by

producing behaviors or traits that alter how people in your environment react to you.


• Evolution refers to a change in the frequency of various genes in a population over generations

• Regardless if helpful or harmful to the species.

• Evolution attempts to answer two questions:

1. How did some species evolve?

2. How do species evolve?



• How species did evolve involves the tentative construction of “evolutionary trees”.

• How species do evolve rests upon some assumptions:1. Offspring generally resemble their

parents for genetic reasons.2. Mutations and recombination of genes

introduce new heritable variations3. Certain individuals successfully

reproduce more than others do.


• Artificial selection refers to choosing individuals with desired traits and making them parents of the next generation.

The Genetic of Behavior

• Common misconceptions about evolution include the following:– Lamarckian evolution - “The use or disuse

of some structure or behavior causes an increase or decrease in that behavior.”

– “Humans have stopped evolving.”– “Evolution means improvement.”– “Evolution acts to benefit the individual or

the species.”


• Evolutionary psychology focuses upon functional and evolutionary explanations of how behaviors evolved.

• Assumes that behaviors characteristic of a species have arisen through natural selection and provide a survival advantage.– Examples: differences in peripheral/color

vision, sleep mechanisms in the brain, eating habits, temperature regulation.


• Some behaviors are more debatable regarding the influence of natural selection.

• Examples include:– Life span length– Gender differences in sexual promiscuity– Altruistic behavior- a behavior that benefits

someone other than the actor• Explanations: reciprocal altruism & kin

selection

The Use of Animals in Research

• Animal research is an important source of information for biological psychology but remains a highly controversial topic.

• Animal research varies on the amount of stress and/ or pain that is caused to the animal itself.


• Reasons for studying animals include:1. The underlying mechanisms of behavior

are similar across species and often easier to study in nonhuman species.

2. We are interested in animals for their own sake.

3. What we learn about animals sheds light on human evolution.

4. Some experiments cannot use humans because of legal or ethical reasons.


• Opposition to animal research varies:– “Minimalists” favor firm regulation on

research and place consideration upon the type of animal used and the amount of stress induced.

– “Abolitionists” maintain that all animals have the same rights as humans and any use of animals is unethical.


• Justification for research considers the amount of benefit gained compared to the amount of distress caused to the animal.– No clear dividing line exists.

• Colleges and research institutions in the United States are required to have an Institutional Animal Care and Use Committee.– Oversees and determine acceptable

procedures.

Education

Chapter1.ppt psych 2