Psychology Module 2, Independent Variable

placebo effect

*subjects expectations influence their behavior *experimenter effect *experimenters expectations of the study unintentionally influence the results of the study

steps in the scientific method

1. formulate question 2. develop hypothesis (prediction) 3. test hypothesis 4. draw conclusions 5. report your results

methods used

1. non-experimental method (observational) 2. correlational method (measurements) 3. experimental method (experiments)

What is the control? Students measured the temperature of the water at different depths in Lake Skywalker and found that the temperature varied.

Lake Skywalker

A florist wants to see if Product X will extend the life of cut flowers so that they last longer. What is the dependent variable?

Life of flowers

What is the control variable in the following sentence: The time it takes to run a mile depends on the person's running speed.

Mile

What is the independent variable in the following sentence: A study was done to find if different tire treads affect the braking distance of a car.

Tire treads

Control Variable

A variable that is kept constant during a controlled experiment.

You want to measure the effect of different amounts of oxygen on the rate of yeast growth. What is the independent variable?

Amount of oxygen

What is the independent variable in the following sentence: The height of bean plants depends on the amount of water they receive.

Amount of water

experiment

a controlled scientific procedure in which you manipulate variables to test a hypothesis (try to learn about cause and effects relationships)

correlation

a measure of the relationship between two variables (x&y)

Orchids were studied to determine if the amount of humidity affected the flowering of these plants. Which of these was the independent variable in this study?

amount of Humidity

variable

anything that can change or vary. (gender, scores, temperatures, age)

What is the dependent variable in the following sentence: A study was done to find if different tire treads affect the braking distance of a car.

Braking distance

What is the control variable in the following sentence: A study was done to find if different tire treads affect the braking distance of a car.

Car

surveys

ask a series of questions to a group about the topic being studied +data from large numbers from people +can study non displayed behaviors -some responses may be inaccurate or false

Quasi-Experimental Design

Compares 2 groups of people but is used when it is not feasible or ethical to use random assignment

You want to test a new drug that supposedly prevents sneezing in people allergic to grass. What is the independent variable?

Drug

What is the control variable in the following sentence: The height of bean plants depends on the amount of water they receive.

bean plants

What is the independent variable: Students measured the temperature of the water at different depths in Lake Skywalker and found that the temperature varied.

depth

population

entire group

You want to see if playing music makes plants grow taller. What is the independent variable in this experiment?

Playing music

Control Group

Group that is exposed to all experimental conditions, except the independent variable.

What is the dependent variable in the following sentence: The height of bean plants depends on the amount of water they receive.

Height of the bean plants.

You want to test a new drug that supposedly prevents sneezing in people allergic to grass. What is the dependent variable?

Sneezing

What is the dependent variable in the following sentence: The time it takes to run a mile depends on the person's running speed.

TIME

An entomologist (bug scientist) wants to determine if temperature changes how many times a cricket chirps. What is the independent variable?

Temperature

Dependent Variable

The experimental factor that is being measured; the variable that may change in response to manipulations of the independent variable

Independent Variable

The experimental factor that is manipulated; the variable whose effect is being studied.

double blind study

neither experimenter nor subjects knows if the subjects are in the experimental or control group

What is the control variable in the following sentence? The higher the temperature of the air in the oven, the faster a cake will bake.

oven/ cake

representative sample

randomly selected group from the larger population

You think that a certain part of your brain is important in memory. To test this, you will remove this part of the brain from rats and see if they remember how to get through the maze. What is the dependent variable in this experiment?

remembering how to get through the maze

You think that a certain part of your brain is important in memory. To test this, you will remove this part of the brain from rats and see if they remember how to get through the maze. What is the independent variable in this experiment?

removing a part of the brain

What is the independent variable in the following sentence: The time it takes to run a mile depends on the person's running speed.

running speed

subject

specific group or individual

correlation coefficient (r)

strength and direction of the relationship +ability to predict the value of the other variables -correlation does not prove causation

case study

study of one subject/group in great detail +a lot of detail -cannot apply results to other

naturalistic observations

study people or animals in their natural environment +realistic picture of behavior -observer effect: tendency of subject to behave differently because they know they are being observed

laboratory observation

study subject in a (laboratory) more controlled behavior +control over environment -artificial situation that may result in artificial behavior

single blind study

subjects do not know if in experimental or the control group but experimenter does

experimental group

subjects who are exposed to what is being manipulated (IV) ex. caffeine

control group

subjects who are not exposed to the IV and may receive a placebo (inactive) treatment (keep the same) ex. decaf

scientific method

system of gathering data so bias and error is reduced

What is the dependent variable? Students measured the temperature of the water at different depths in Lake Skywalker and found that the temperature varied.

temperature

What is the independent variable in the following sentence: The higher the temperature of the air in the oven, the faster a cake will bake.

temperature of the oven

observer bias

tendency of observers to see what they expect/want to see

Experimental Group

the group in an experiment that receives the variable being tested

dependent variable (DV)

the measurable effects of the changes to the IV (wait and see)

What is the dependent variable in the following sentence: The higher the temperature of the air in the oven, the faster a cake will bake.

the time it takes the cake to bake.

independent variable (IV)

the variable the researcher manipulates to observe the effects or the change (I change it)

An entomologist (bug scientist) wants to determine if temperature changes how many times a cricket chirps. What is the dependent variable?

times a cricket chirps