Unit 2: The science of psychology

Science

A systematic way of gathering and evaluating evidence

Guided by ruled that promote consistency and replicstion

Used to develop principles about vehavior

The scientific approach

Observation

Measurement

Data analysis

Experimental research design

Involves manipulating one variable

Measures irs effect on another variable

Allows conclusions about cause and effect

Hypothesis

A tentative and testable prediction

Regarding the relationship between variables

Stated in a falsifiable way

Indepedent variable

The variable manipulated by the researcher

Dependent variable

The variwble that is measured

Extraneous variables

Any other variab,es than the IV that may influence the DV

If not controlled may become confounds: experimenter expectations or demand characteristics

Experimenter expectancy effect

Researxher expectations influence outcomes (e.g. facial expressions, body language, getsures, feedback timing)

Demande characteristics

Cues that shaoe participant behavior (e.g. task clues, intructions, repeated measure)

Participants

Key element of experimental research design

Organisms whise behavior is being studied

Random assignments

Key element of experimental research design research design

Assignment if oarticipants to the different conditions of an experiment entirely at random

Each participant has an equal likelihood of being assigned to any particular condition

Experimental group

Key element of the experimental reseqrch design

Recieves the treatment or condition of interest

Control group

Key element of experimental research design

Does not recieve the experimental trestment

Serves as the comparison group

Placebo treatment

A pharmacologicall inert substance such as a sugar pill often administered as a control in testing new drugs

Placebo effect

A clinically significant response to a therapeutical

A psychologicql phenomenon when the untreated subject may falsely believe they have recieved the actual treatment and report positive symptoms

Single blind procedure

A procedure in which the participants are unaware of the experimental conditions under which they are operating

Double blind procedure

A procedure in which bothe the participants and the experimenters interscting with them are unaware of the particular experimental conditions

Correlational Research Design

A type of research in which the relationship between variables are observed and measured without manipulating the variables

Pearson correlation coefficient

A non unit numerical index reflecting the degree of linear relationship between two variables

The sign indicstes the directionality of the relationship

The absolute value reflects rhe strangth if the relationship

Positive relationship

Pearson coefficient value of +1.0 indicates a perfect relationship

Valuesof each variable rise and fall together

Negative relationship

Pearson correlation coefficiant below 0 indicate this relationship

-1.0 indicstes a perfect relationship

As va,ues of one variable increase, those of the other variable stop

Quasi-Experimental Design

Resembles experimental research but does not include all the festures if a true experiment

The research manipulates an independent variable, but participants are nit random,y assigned to experimental and control/comparison conditions

Because participants are not random,y assigned, pre-existing differences between groups may act as confounding variables making casual conclusions less certsin

Longitudinal research design

A research design in which the same participants are studied eepeatedly over a period of time to examine change or development

Ex. A multiyear study that follows the same children and assesses their cognitive development at several points over tume

Inferential statistics

A branch of mathematics researcherd used to record organize, analyze, summarize, and interpret data to answer scientific questions

Descriptive statistics

Data are also used descriptively with techniques and procedures used ro describe and represent quantifiable information

Methids used to riganize, summarize, and describe the data that have been collected

Measures of central tendency

Numerical values that describe the center or typical value of a set of data

The three most common are mean, median, mode

Mode

The most frequently occuring score in the distribution

Median

The score that divides a frequency distribution exactly in half, the same number of scores fall abive and below the median

Mean

The sum of a set of scores in a distrubution divided by the number of score. Also known as the average

Range

The highest score in the distribution minus the lowest score

Standard deviation

The square root of the sum of the squared deviations from tje mean divided by the number of scores in the distribution

Normal distribution

Symettrical bell shaped distribution

Mean=median=mode

Sxores become less common the farther away from the mean

Helps us judge where and individual score falls within that