The Basics of Experimentation: Concepts, Definitions and Examples

The Debate: What is learned? Behaviorists – (e.g., Clark Hull) stimulus- response (S-R) associations; only observable behavior can be studied scientifically. Behaviorists – (e.g., Clark Hull) stimulus- response (S-R) associations; only observable behavior can be studied scientifically. Cognitivists – (e.g., Edward Tolman) S-S associations, such as the relations among distal cues that form cognitive maps, can be inferred from observable behavior. Cognitivists – (e.g., Edward Tolman) S-S associations, such as the relations among distal cues that form cognitive maps, can be inferred from observable behavior.

A process of elimination… Place units (cells) in the hippocampus respond to an animal’s location within the environment, not to a specific sensory stimulus, motor behavior or motivational incentive.

A Demonstration of Place Cell Firing

The activity of multiple hippocampal neurons (ensembles) during REM sleep matches the place activity of the same neurons when the animal was awake. Are the animals dreaming of past places they have experienced?

Do rats and other mammals dream? Some papers equate REM sleep with “dreaming sleep” One function of REM sleep may be to help consolidate memory of recent events

Experimental variables Every experimental variable has two definitions: 1) Conceptual – used in everyday language 2) Operational – used in conducting an experiment. Dreaming is conceptual and REM sleep is operational.

Experimental variables Hypotheses are often stated in conceptual terms but experiments require operational definitions. How will you operationally define variables in your study? This is a critical step in setting up the Methods section.

Operational definitions Experimental – what was done to create the treatment conditions (IV). Measured – What procedures were followed to assess the effect of the treatment (DV).

How do you define spatial learning, especially if it is possible that animals may use a simpler form of stimulus- response (S-R) learning? Measured operational definitions

Hypothetical Constructs Spatial learning is a hypothetical construct – an unseen process that is postulated to explain behavior. The same construct variable can be defined in different ways in different experiments.

Measured operational definitions In the water maze study: Place response – escaping to the hidden platform (S-S cognitive association). Cue response – escaping to the visible platform (S-R association).

start Cue Response start Place Response

Measured operational definitions In a different Water maze study: A place response – visiting the old location (spatial learning) before escaping to the visible platform (S-R learning) at a new location. A cue response – not visiting the old location before escaping to the visible platform (S-R association).

start Cue Response start Place Response

Measured operational definitions In a Plus Maze study: Place response – Turning left or right at the choice point depending the start location (spatial learning). Turning response – Always turning left regardless of the start location (S-R association).

Measured operational definitions Water maze: A place response – escaping to the hidden platform (S-S cognitive association). A cue response – escaping to the visible platform (S-R association).

Independent Variables (IV) What makes the IV “independent”? a) It is an aspect of the experiment that varies. b) It is the dimension that the experimenter manipulates. c) Its values are created by the experimenter. d) Its values are not affected by anything else that happens in the experiment.

Dependent Variables (DV) What makes the Dependent variable “dependent”? a) It is an aspect of the experiment that varies. b) It is the dimension that the experimenter does not manipulate. c) It values depend on the effects of the IV. d) It is an objective measure of behavior that is observed in the experiment.

Independent Variables (IV) What is the minimum number of levels of the IV in any experiment? a) 0 b) 1 c) 2 d) 3 e) 4

Independent Variables (IV) Three kinds of IV: 1. Environmental variables (e.g., music) 2. Task variables (hidden vs visible platform) 3. Subject variables (sex or personality or learning strategy).

Defining subject variables

Two room protocol Would fast place learners in room A also be good latent learners in room B?

Results Fast place learners = 2,3,4,6,9,10 Good latent learners = 2,3,7,8,9,12

Inverse relation