Psychology. Chapter 1: The Science of Psychology

Placebo effect

Improvement due to the expectation of improving because of receiving treatment.

The variability of the scores

In addition to describing the typical score, we need to determine the variability of the scores. We could use the range—the difference between the high- est and lowest scores—but unusually low or high scores distort it. The measure of variability most often used is the standard deviation, the average extent that the scores vary from the mean of the distribution.

Experimental group

In an experiment, the group exposed to the independent variable.

Control group

In an experiment, the group not exposed to the independent variable.

Inferential statistical analyses

Statistical analyses that allow researchers to draw conclusions about the results of a study by determining the probability that the results are due to random variation (chance). The results are statistically significant if this probability is .05 or less.

Population

The entire group of people that a researcher is studying.

Biological Perspective

A research perspective whose major explanatory focus is how the brain, nervous system, and other physiological mechanisms produce behavior and mental processes. Biological psychologists look for causes within our physiology, our genetics, and human evolution. They argue that our actions and thoughts are functions of our underlying biology. In addition to the impact of brain chemistry, biological psychologists also study the involvement of the various parts of the brain and nervous system on our behavior and mental processes.

Internal Factors

Biological and cognitive.

Research Methods used by Psychologists

Psychology researchers use the same research methods. These methods fall into three categories: descriptive, correlational, and experimental.

The Four Major Research Perspectives

Biological, cognitive, behavioral, and sociocultural. These perspectives are complementary and they are grouped as follow: The biological perspective and the cognitive perspective focus on causes that stem from within us (internal factors); the behavioral perspective and the sociocultural perspective focus on causes that stem from outside us (external factors).

Placebo group

A control group of participants who believe they are receiving treatment, but who are only receiving a placebo.

Double-blind procedure

A control measure in an experiment in which neither the experimenters nor the participants know which participants are in the experimental and control groups.

Random Assignment

A control measure in which participants in a sample are randomly assigned to the groups or conditions in an experiment. Used only in experiments. Allows researcher to control for possible influences of individual characteristics of the participants on the behavior(s) of interest.

Operational definition

A description of the operations or procedures that a researcher uses to manipulate or measure a variable.

Nocebo effect

A negative placebo effect due to the expectation of adverse con- sequences from receiving treatment.

Behavioral Perspective

A research perspective whose major explanatory focus is how external environmental events condition observable behavior. According to the behavioral perspective, we behave as we do because of our past history of conditioning by our environment. There are two major types of conditioning, classical (or Pavlovian) and operant. Classical conditioning is important in determining our behavior, but behaviorists believe operant conditioning is even more important. Operant conditioning involves the relationship between our behavior and its environmental consequences (whether they are reinforcing or punishing). Simply put, if we are reinforced for a behavior, its probability will increase; if we are punished, the probability will decrease. The point to remember here is that environmental events condition our behavior and are the causes of it.

Cognitive Perspective

A research perspective whose major explanatory focus is how mental processes, such as perception, memory, and problem solving, work and impact behavior. Cognitive psychologists study all aspects of cognitive processing from perception to the higher-level processes, such as problem solving and reasoning.

Sociocultural Perspective

A research perspective whose major explanatory focus is how other people and the cultural context impact behavior and mental processes. This perspective focuses on the impact of other people (individuals and groups) and our cultural surroundings on our behavior and mental processing.

Correlational study

A research study in which two variables are measured to determine if they are related (how well either one predicts the other). A variable is any factor that can take on more than one value. For example, age, height, grade point average, and intelligence test scores are all variables. In conducting a correlational study, the researcher first gets a representative sample of the relevant population. Next, the researcher takes the two measurements on the sample. (a) Correlation Coefficient. A statistic that tells us the type and the strength of the relationship between two variables. The sign of the coefficient (+ or -) indicates the type of correlation—positive or negative, respectively. The absolute value of the coefficient (0.0 to 1.0) represents the strength of the correlation, with 1.0 being the maximum strength. A positive correlation is a direct relationship between two variables. A negative correlation is an inverse relationship between two variables. (b) Scatterplot. A visual depiction of cor- relational data in which each data point represents the scores on the two variables for each participant. (c) The Third-variable problem. An explanation of a correlation between two variables in terms of another (third) variable that could possibly be responsible for the observed relationship between the two variables.

Random Sampling

A sampling technique in which a sample of participants that is representative of the population is obtained. Used in experiments and some other research methods such as correlational studies and surveys. Allows researcher to generalize the findings to the relevant population.

Random sampling

A sampling technique that obtains a representative sample of a population by ensuring that each individual in a population has an equal opportunity to be in the sample.

Meta-analysis

A statistical technique that combines the results of a large number of studies on one experimental question into one analysis to arrive at an overall conclusion.

Placebo

An inactive pill or a treatment that has no known effects.

External Factors

Behavioral and sociocultural.

The standard deviation

Is especially relevant to the normal (bell-shaped) frequency distribution. Sixty-eight percent of the scores in a normal distribution fall within 1 standard deviation of the mean, 95 percent within 2 standard deviations, and over 99 percent within 3 standard deviations. These percentages hold true regardless of the value of the standard deviation. They also enable us to compute the percentile rank for a specific score in a normal distribution. The percentile rank for a score is the percentage of the scores below it in the distribution of scores. All distributions are not symmetric like the normal distribution. Two important nonsymmetric distributions are the right-skewed and left-skewed distributions. In a right-skewed distribution, there are some unusually high scores, leading to the mean being greater than the median; in a left-skewed distribution, there are some unusually low scores, leading to the mean being less than the median. In both cases, the median should be used because the mean is distorted toward the tail of the distribution.

The Mean

Is merely the arithmetical average.

The Median

Is the middle score when the distribution is arranged in ascending or descending order.

The Mode

Is the most frequently occurring score.

Psychology

Is the science of behavior and mental processes. Psychologists attempt to understand all aspects of both our observable behavior, such as speech and physical movement, and internal mental processes, such as remembering and thinking, which cannot be directly observed. Psychologists may be found in any number of roles, including teaching, researching, consulting, and yes, counseling troubled people.

Experimental Research

The key aspect of experimental research is that the researcher controls the experimental setting. The only factor that varies is what the researcher manipulates. It is this control that allows the researcher to make cause-effect statements about the experimental results. This control is derived primarily from two actions. First, the experimenter controls for the possible influence of third variables by making sure that they are held constant across all of the groups or conditions in the experiment. Second, the experimenter controls for any possible influences due to the individual characteristics of the participants, such as intelligence, motivation, and memory, by using random assignment—randomly assigning the participants to groups in an experiment in order to equalize participant characteristics across the various groups in the experiment. If the participant characteristics of the groups are on average equivalent at the beginning of the experiment, then any differences between the groups at the end of the experiment cannot be attributed to such characteristics.

Sample

The subset of a population that actually participates in a research study.

Hindsight bias (I-knew-it-all-along phenomenon)

The tendency, after learning about an outcome, to be overconfident in one's ability to have predicted it.

Descriptive Methods

There are three types of descriptive methods: observational techniques, case studies, and survey research. The main purpose of all three methods is to provide objective and detailed descriptions of behavior and mental processes. However, these descriptive data only allow the researcher to speculate about cause-effect relationships—to develop hypotheses about causal relationships. Such hypotheses must then be tested in experiments. With this important limitation in mind, we'll consider the three descriptive methods one at a time. (a) Observational techniques. The researcher directly observes the behavior of interest. Such observation can be done in the laboratory, in its natural setting, and the researcher does not intervene in the behavior being observed, or can be done as an participant observation, where the observer becomes part of the group being observed. (b) Case Studies. A descriptive research method in which the researcher studies an individual in depth over an extended period of time. The most common use of case studies is in clinical settings with patients suffering specific deficits or problems. The main goal of a case study is to gather information that will help in the treatment of the patient. The results of a case study cannot be generalized to the entire population. They are specific to the individual that has been studied. However, case study data do allow researchers to develop hypotheses that can then be tested in experimental research. (c) Survey Research. A descriptive research method in which the researcher uses questionnaires and interviews to collect information about the behavior, beliefs, and attitudes of particular groups of people. Developing a well- structured, unbiased set of survey questions is a difficult, time-consuming task, but one that is essential to doing good survey research.

Psychologists' conclusions are based upon scientific research.

Those conclusions provide the best answers to questions about human behavior and mental processing. Whether these answers sometimes seem obvious or sometimes agree with common sense is not important. What is important is understanding how psychologists conduct this scientific research in order to get the best answers to their questions.

What is the major goal of psychologists?

To explain human behavior and mental processes. To explain means to know the causes of our behavior and mental processes. To facilitate your understanding of these perspectives, I discuss them in two different pairs based on the type of causal factors that they emphasize— internal factors or external factors.

How to Understand Research Results

To understand research findings, psychologists use statistics—a branch of mathematics- that provides procedures for the description and analysis of data. In this section, we were concerned with descriptive statistics. Measures of central tendency allow a researcher to describe the "typical" score for a distribution of scores concisely. There are three such measures: mean, median, and mode. Of these three measures, the mean is used most often. However, if unusually high or low scores in the distribution distort the mean, then the median should be used.

Designing an experiment

When a researcher designs an experiment, the researcher begins with a hypothesis (the prediction to be tested) about the cause-effect relationship between two variables. One of the two variables is assumed to be the cause, and the other variable is the one to be affected. The independent variable is the hypothesized cause, and the experimenter manipulates it. The dependent variable is the variable that is hypothesized to be affected by the independent variable and thus is measured by the experimenter. Thus, in an experiment the researcher manipulates the independent variable and measures its effect on the dependent variable while controlling other potentially relevant variables. If there is a causal relationship between the independent and dependent variables, then the measurements of the dependent variable are dependent on the values of the independent variable, hence the name dependent variable.