Chapter 2

• Independent variable


  Variable that is manipulated or changed by the experimenter
• Dependent variable


  Variable that is measured or observed and expected to change as a result of changes in the independent variable
• Control group


  Group that does not receive the experimental treatment
• Experimental group(s)


  Group(s) that receive the experimental treatment
• Placebo


  An inactive substance or treatment that is designed to be indistinguishable from the actual treatment being studied
• Within-subjects design


  Experimental design where each participant experiences both the control and experimental conditions
• Between-subjects design


  Experimental design where participants are randomly assigned to either the control or experimental condition
• Probability of difference obtained occurred by chance


  Statistical significance of the difference between the control and experimental groups
• Between-Subjects Design


  1. Test 1

  2. Students A | N

  3. Students O | Z

  4. Placebo

  5. Drug

  6. Compare means between the 2 groups and determine the probability of getting the difference observed
• Within-Subjects Design


  1. Test 1

  2. Students A | N

  3. Students O | Z

  4. Placebo

  5. Drug

  6. Test 2

  7. Students A | N

  8. Students O | Z

  9. Drug

  10. Placebo

  11. Compare scores between the 2 tests for each individual and determine the probability of getting the differences observed
• Disadvantages of between-subjects design

  • May be pre-existing difference
• Disadvantages of within-subjects design

  • Time-consuming
• Placebo effect


  Occurs when participants experience an improvement in their condition simply because they believe they are receiving an effective treatment, even though the treatment may be inert
• Single-blind


  Experimental design where the participant is unaware of whether they are receiving the actual treatment or a placebo
• Double-blind


  Experimental design where both the participant and the experimenter are unaware of whether the participant is receiving the actual treatment or a placebo
• Balanced Placebo design


  1. Group 1 expects placebo and gets placebo

  2. Group 2 expects placebo and gets drug

  3. Group 3 expects drug and gets placebo

  4. Group 4 expects drug and gets drug
• Nonexperimental research


  Looks for a relationship between two measured events, with no variable being manipulated
• Nonexperimental research cannot prove cause and effect, only correlation
• Unconditioned behaviour


  Spontaneous, unlearned behaviour
• Measures of unconditioned behaviour in non-humans

  • Spontaneous Motor Activity (SMA)
  • Open field test
  • Inclined plane test
  • Elevated plus maze
  • Paw lick latency test
• Classical conditioning


  Learning process where a neutral stimulus becomes associated with a meaningful stimulus, resulting in a conditioned response
• Classical conditioning example


  • Pavlov's dog
• Unconditioned stimulus (UCS)


  Stimulus that naturally and automatically triggers a response
• Unconditioned response (UCR)


  Unlearned, automatic response to an unconditioned stimulus
• Conditioned stimulus (CS)


  Neutral stimulus that, through association with the unconditioned stimulus, comes to elicit a conditioned response
• Conditioned response (CR)


  Learned response to a conditioned stimulus
• Operant conditioning


  Learning process where behaviour is controlled by its consequences
• Operant conditioning example


  • Skinner's rat
• Schedules of reinforcement


  • Fixed Ratio (FR)
  • Variable Ratio (VR)
  • Fixed Interval (FI)
  • Variable Interval (VI)
• Avoidance-escape task


  Experimental procedure where an animal learns to avoid or escape an aversive stimulus (e.g. shock)
• Punishment


  Consequence that decreases the likelihood of a behaviour occurring
• Discriminative stimulus


  Stimulus that signals the availability of reinforcement for a particular response
• Discrimination learning task


  Procedure where an animal learns to make a specific response in the presence of one stimulus and a different response in the presence of another stimulus
• Substitution test


  Procedure where a drug is tested to see if it can substitute for another drug in a discrimination learning task
• Generalization


  Phenomenon where a response learned to one stimulus also occurs to similar stimuli
• Dissociation


  Phenomenon where learning during a drug state only manifests itself during that drug state
• Measures of reinforcing properties of drugs (abuse liability)

  • Rate of self-administration
  • Progressive ratio schedule
  • Choice
  • Conditioned place preference
  • Medial forebrain bundle (self-stimulation - ICSS)
• Visual Analogue Scales (VAS)

  Subjective self-report measure where participants indicate their response on a continuous line
• Profile of Mood States (POMS)

  Standardized questionnaire that measures various mood states
• Drug state discrimination


  Procedure where participants indicate whether they have received an active drug or a placebo