Download experimental basics

The Basics of
Experimentation:
Concepts, Definitions and
Examples
The Debate: What is learned?
Behaviorists – (e.g., Clark Hull) stimulusresponse (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.

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).
Measured operational definitions
How do you define spatial learning,
especially if it is possible that animals
may use a simpler form of stimulusresponse (S-R) learning?
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).
Cue Response
start
start
Place Response
start
start
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).
Cue Response
start
start
Place Response
start
start
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