What is Psychology?

I. Definition: Psychology is the scientific study of behavior and mental processes

A. Behavior vs. mental processes: Observable vs. unobservable phenomena

B. Psychology studies the behavior of both humans and lower animals

C. Scientific vs. nonscientific approaches to psychology

II. Conceptualizing psychology in terms of levels of explanation

A. Three important levels of explanation

1. The group level – behavior is explained in terms of the biological or social groups people belong to and in terms of the processes that mold these groups. Examples of biological groups are: species and the biological sexes. Examples of social groups are: socio-economic classes, cultural and ethnic groups, religious groups, gender. The family classifies as both a biological and social group. Processes studied include biological evolution, cultural evolution, and the effects and dynamics of social groups.

2. The individual level – behavior is explained in terms of biological and environmental factors that influence the behavior of individuals. These factors can include biological factors (heredity, genes, hormones, brain structure and physiology), past environmental factors (family rearing, past rewards and punishments), and current environmental factors (the current social setting, the people your are with). Processes studied include behavior genetics, neurophysiology, learning, development, and social psychological processes.

3. Mediating variables – hypothetical factors that exist within individuals and that are inferred from behavior. These internal factors include: personality traits, intelligence, beliefs, attitudes, emotional states, consciousness.

B. What psychology hopes to explain: the individual’s behavior. Behavior can be divided into three parts or components: thought (the cognitive side of life), feeling (the emotional side of life), and overt behavior (the action side of life). Thus, psychology attempts to explain factors that influence individuals’ thoughts, feelings, and overt behaviors.

C. Defining psychology and other social sciences in terms of levels of explanation

1. Psychology tends to emphasize individual level factors and mediating variables as “causes” of human behavior; the unit of analysis is the individual

2. Other social sciences, such as sociology and anthropology, emphasize group-level factors that influence human behavior

The Philosophical Roots of Psychology

I. Some basic questions that have puzzled philosophers

A. What is the nature of the “mind” and where does it come from?

B. How much is the “mind” influenced by experience, and how much of the contents of the mind are innate – the famous “nature-nurture” question

C. What is the nature of “reality”? How do people acquire knowledge? How well do our beliefs reflect reality, and to what degree are they subjective and “socially constructed”? When are our beliefs and perceptions valid, and when are they delusions and illusions?

II. Some famous philosophical answers to these questions

A. The British associationist (or “empiricist”) philosophers: John Locke (1632-1704), David Hume (1711-1776), James Mill (1773-1836), John Stewart Mill (1806-1873)

1. Lock’s notion of the infant’s mind as a tabula rasa (blank slate); the doctrine that all the contents of the mind came originally through the senses. For example, the idea or concept of a rose develops from sensory experiences – the sight, smell, and feel of a rose. Sensory experiences that occur at the same time are associated with one another. This is how ideas are “glued together” and how concepts are formed.

2. Locke’s famous thought experiment: What would happen if a man, blind from birth, were given sight as an adult? Would he see as you or I do? Is “seeing” learned, or is it “wired into us”?

3. The British associationists provided a philosophical foundation for psychologists who emphasized environmental causes of behavior and also for the study of associative kinds of learning such as classical conditioning (e.g., when a dog associates a bell that repeatedly rings at the same time food is presented, and thus learns to salivate to the bell)

B. René Descartes (1596-1650) – famous French philosopher and mathematician

1. Developed an early notion of a reflex – a simple connection between a stimulus (pain from a candle flame) and response (pulling your hand away)

2. The mind-body problem and Descartes notion of mind-body dualism: What is the relation between the mind and the body? Can the mind and mental experience be explained totally in physical terms? Descartes, partly based on theological considerations, concluded that the mind is separate from the body and that the two interact through the pineal gland. This doctrines seems to contradict basic scientific notions, such as the conservation of mass and energy. How can a non-physical thing (the mind) affect a physical thing composed of matter and energy (the body)? The opposing “materialist” or “monist” position argues that the mind and the body are one thing, that the mind can be explained in physical terms, and that when the body dies, the mind dies too.

3. Descartes “doctrine of innate ideas” – Does the “mind” come into existence with some structure, or is it a “blank slate”? Descartes thought there was some initial structure. An analogy: Does a new computer come with some “structure” built into it? The distinction between “hardware” and “software.” Does a computer (and the human brain) come preloaded with certain kinds of hardware and software?

C. Immanuel Kant (1724-1804) – famous German philosopher

1. Kant’s Critique of Pure Reason proposed the doctrine that experienced reality is determined by a priori mental structure as well as by sensory experience. Some concrete examples: Must the newborn possess some sense of three-dimensional space, time, and cause-effect relationships? If the newborn human “computer” (the brain) were not “preloaded” with certain kinds of structure (“software”), then experience would be utterly chaotic

2. In the philosophical debates and conjectures of the British associationists, Descartes, and Kant we see the beginnings of the famous “nature-nurture” debate and early attempts to explain the nature of human experience, consciousness, and mental processes

Psychology as a Science

I. Scientific Method

A. Empirical data -- Measured reality is the test of all theories and hypotheses

1. Operational definitions -- defining concepts in terms of concrete measurement procedures; operational definitions allow scientists to replicate studies; they make science a publicly observable route to knowledge

B. Theories -- Models of how variables (measured concepts or factors) are related to one another; models of how variables influence (cause) other variables

1. Good theories explain data

2. Good theories are relatively simple (principle of parsimony); "parsimonious" literally means "stingy"; a parsimonious theory makes no unnecessary assumptions; it explains things as simply as possible

3. Good scientific theories can be disproven

II. Psychological Research

A. Kinds of data

1. Subjective data; subjective self-reports

Problems: subject bias, dishonesty, lack of self- awareness

2. Behavioral data

Problems: Inability to measure mental states and processes; behaviors may be poor operational definitions of what your are trying to measure

II. Two kinds of studies in psychology

A. Correlational studies

1. Definition: In a correlational study the researcher measures variables, often in some natural setting, to see whether they are related to one another. Example: is drug use among college students related to their GPA?

2. The statistic used to measure the degree of linear (straight line) relationship between two variables is the correlation coefficient. This is a computed number that may range from -1 to +1. The closer a correlation coefficient is to -1 or +1, the stronger the relationship between the two variables. The closer a correlation coefficient is to 0, the weaker the relationship between two variables.

3. Some actual correlations from psychological research: The correlation between amount of TV children watch and the aggressiveness is around .2 to .3. The correlation between students' IQ and their high school or college grades is around .5 to .6. The correlation between stress and illness is around .3. The correlation between people's measured attitudes and their behavior is on average around .4.

4. Weaknesses of correlational studies: They do not tell us about cause-effect relationships. The reason is that correlational studies can only tell us if two variables (A and B) are related to one another. They cannot tell us if A causes B, if B causes A, or if A and B are both caused by some third variable (C).

B. Experiments (Experimental studies)

1. Definition: In psychological research, an experiment has two defining characteristics:

a. One variable, termed the independent variable, is manipulated (that is, controlled by the experimenter) to determine whether it has an effect on a second variable, termed the dependent variable

b. Participants are randomly assigned to experimental conditions in an experiment. In the simplest experiment, there are two conditions (that is, two levels of the independent variable). Random assignment means that any participant has an equal chance of being assigned to either of the two conditions before the experiment is conducted.

2. Strengths and weakness of experiments

a. Strengths: Experiments allow researchers to make cause-effect conclusions. Random assignment is what permits cause-effect conclusions in experiments. Experiments allow researchers to control the setting and thus reduce "noise" in their measurements.

b. Weaknesses: Experiments may be artificial; experiments may not look at "real-life" variables or real-life levels of variables; for practical or ethical reasons, experiments may be hard to carry out; some variables cannot be experimentally manipulated

Biological Psychology

I. Historical introduction

A. Nerves and their effects: Robert Whytt (1751) produces movement by pricking spinal cord; he concludes that "nervous power" rather than arterial blood produces motor responses (movement)

B. The nerve impulse is electrical

1. Luigi Galvani (1737-1798) -- fresh frogs for dinner

2. Alessandro Volta (1745 -1827) -- the Voltaic pile and the discovery of electricity

3. Hermann von Helmholtz (1821-1894) -- the nerve impulse moves at about 80-100 mph

II. Some architectural principles -- the organization of nerves and the nervous system

A. Bell-Magendie Law -- in early 1800s, researchers discover that sensory nerves enter at back of spinal cord; motor nerves emerge from front

B. Spinal reflexes -- automatic stimulus-response connections; sensory nerves carry information to spinal cord, interneurons connect to motor neurons, which carry information back out to muscles; afferent (input) and efferent (output) nerves

C. Sherrington's discovery in 1906: inferring the existence of synapses by comparing the time it takes a reflex to occur with the time of nerve conduction

D. Main parts of nervous system: central nervous system (brain and spinal cord); peripheral nervous system -- somatic (voluntary) and autonomic (involuntary) branches; the sympathetic and parasympathetic branches of the autonomic nervous system

III. The Brain

A. Main parts: forebrain, midbrain, and hindbrain (medulla, pons, and cerebellum); the cerebral cortex and its lobes (frontal, parietal, occipital, and temporal); the limbic system; the thalamus -- the great sensory relay station of the brain

B. Early ways of studying the brain

1. Pierre Flourens (1794-1867) and ablative surgery. Assumption: psychological functions are controlled by various parts of the brain; if you remove or destroy that brain part, you'll eliminate the function; problems with this approach

2. Electrical brain stimulation -- Fritsch and Hitzig's (1870) experiments on dogs; demonstration of the motor cortex in the back of the frontal lobe; the sensory cortex in the parietal lobe

3. "Natural experiments" -- injuries, strokes, and tumors; the discovery of "language centers"; Broca's (1861) patient and Broca's area of the left frontal lobe; Wernicke's area of the left temporal lobe

Right vs. Left Brain

I. Early evidence

A. Data from stroke victims: speech disturbances associated with paralysis of the right side; contralateral control of body by brain -- right side of brain controls left half of body, and vice versa

B. Broca's (1861) discovery: patient suffering from lost of speech and paralysis of right side died; autopsy showed lesion in a region of the left frontal lobe -- Broca's area; by 1864 Broca had associated damage to the left side of the brain with speech problems

C. Wernicke's area: a corresponding area in the temporal lobe; damage to this region led to problems with speech comprehension

D. Another view: Broca's area is related to the syntactic functions of language; Wernicke's area is related to the lexical "dictionary"

E. The doctrine of "cerebral dominance" -- that the left hemisphere is most important, responsible for speech and purposeful behavior

II. The neglected left hemisphere

A. Observations about effects of tumors -- damage to right hemisphere could affect recognition of objects, faces, and places

B. Large scale study in the 1930s used newly developed intelligence tests to study effects of brain injuries on intellectual performance; left brain injuries led to poor performance on verbal tests (reading comprehension, analogies, word definitions), whereas right brain injuries led to poor performance on nonverbal tests (puzzle assembly, completion of missing parts in drawings, spatial relationships)

C. Clinical evidence: right hemisphere damage led to strange syndromes such as "hemispatial neglect," or facial agnosia -- the inability to recognize or discriminate faces

D. Some evidence that certain musical abilities may be located in the right hemisphere

E. the Wada test -- anesthetizing half the brain; evidence about location of language abilities in normal brains

III. Split-brain research

A. In 1940s operations were carried out to control epilepsy by cutting the corpus callosum -- the huge band of nerve fibers that connect the two halves of the brain; puzzling result: the surgery seemed to have little effect on patients

B. In early 1950s, Myers and Sperry conduct landmark study on cats in which the corpus callosum had been severed; they showed that visual information presented to one hemisphere was not available to the other hemisphere; thus one half of the cat's brain could be learn a different task from the other half

C. Human split brains: if information is presented in the right visual field, it goes to the left half of the brain, and vice versa; when information was presented to the right visual field (left side of brain), people could verbally report what they saw; when information was presented to the left visual field, people could not verbally report what they saw; however, they could pick out the seen object with their left hand

D. Do split brain patients have two minds? The relation of split-brain research to Descartes' mind-body problem

Nerve Cells and How They Operate

I. Neurons

A. Cajal's discovery: there are discrete nerve cells

B. Parts of neurons: soma, axon, dendrites; the myelin sheath

C. Neural transmission:

the resting potential (a voltage difference of about 70 millivolts between inside of cell, which is negative, and the outside of cell, which is positive); the resting potential is maintained by sodium and potassium ions (charged particles)

the action potential: a wave of depolarization (voltage reversal) that travels down an axon

Laws of neural transmission:

The "all-or-none" law

The refractory period puts limitations on the number of times per second a nerve cell can fire

I. Neurons (Continued)

D. Neural codes

1. Analogy to the digital codes of computers. All information in computers (numbers, letters) are coded in terms of binary pieces of information -- "0's" and "1's"; for example, the ascii (American Standard Code for Information Interchange) for the number “5” is “00000101” and for the letter “a” is “01000001”

2. Temporal codes: coding information in terms of the frequency of nerve impulses; for example, in the optic nerve brighter light may be coded by greater frequency of nerve impulses

3. Place codes: coding information in terms of which neurons are firing; Muller's "doctrine of specific nerve energies"; Examples: optic nerves carry information about light patterns, the auditory nerves carry information about sound patterns; the place theory of pitch perception holds that the particular hair cells stimulated along the basilar membrane determines what pitch we hear

I. Neurons (Continued)

F. The synapse

1. Neurotransmitters chemically carry information across the synapse; generally, neurotransmitters have either inhibitory or excitatory effects -- that is, they either get the next nerve cell to fire less or more; there are many different neurotransmitter substances which may function in different "circuits" in the brain; examples are dopamine (involved in Parkinson's disease), serotonin (involved in mood, depression, appetite, and sleep; the drug Prozac works on serotonin), GABA (involved in anxiety), endorphins (involved in pain and pleasure)

2. Drugs that affect synapses: agonists enhance the effect of a neurotransmitter; antagonists block or interfere with the effect of a neurotransmitter

The Evolution of the Nervous System

I. Darwin's theory of evolution

A. Three main assumptions:

1. Variation

2. Inheritance

3. Natural selection: Traits that foster survival and reproduction in a given environment are more likely to be passed on to the next generation; in a sense, it is the environment that "selects" in natural selection; if environments change, then the traits that foster survival will change

B. Darwin's theory is not teleological; there is no intention or “purpose” to evolution

C. Modern twists on evolutionary theory: the "selfish gene" view of evolution: focusing on gene survival rather than individual survival; Kin selection (inclusive fitness): because animals share genes with relatives, natural selection can sometimes foster "altruistic" behaviors to relatives

II. The evolution of nervous systems

A. Protozoans versus metazoans: Once multi-cell animals evolved, there were "communication problems": how to get outside information into the animal (issues of sensation and perception); how to coordinate parts of the body (internal communication); the nervous system evolved to solved such problems

B. Life viewed as an information process

Process	Code	Information Coded
Biological evolution	Genes, DNA	Adaptive or "good" variants of physical structure
Social or cultural evolution	Language & writing	Adaptive or "good" ideas and social customs
Learning: Changes in Behavior of an individual based on experience	Nerve impulses and connections	Adaptive behavior, useful representations of the environment and of previous experience

III. An example of the evolution of sensory systems and neural codes: the evolutionary war between moths and bats; Roeder's research

A. The acoustical "war" between moths and bats: bats hunt by echo location; moths avoid bats by detecting bat chirps

B. The echo location system: bats produce brief, rapid ultrasonic chirps 10 to 100 times per second

C. Moths have typanic organs in the sides of the thorax (chest); each ear has only two neurons coming from it; coding in moths' ear cells; recording the action potentials from the nerve cells in moths' ears

D. Actual evidence from moths and bats in the field

E. Why do moths (and people) have two ears? Recording from two ears at once.

IV. A philosophical question: If the moth's ear is a "bat detector," what then is the human ear?

A. The frog's visual system

B. Is our perception of the world limited by our biological makeup?