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Domjan Chapter 3, Chapter 4: 87-103 (sections 4-1 and 4-2)

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Initial Responses to the Stimuli

• CS does not elicit the conditioned response initially, but comes to do so as a result of becoming associated with the US
• US is effective in eliciting the target response from the outset (unconditionally) without any special training
• Identifying potential CSs and USs requires comparing the responses elicited by each stimulus before conditioning
  • Makes comparison relative

Food pellets flavored with sucrose

• Taste of sucrose pellets may serve as a CS in a taste-aversion conditioning procedure
• Participants will acquire aversion to eating the sucrose pellets

Sign tracking with rats

• Inserting response lever (CS) before each delivery of pellet (US)
• Rats began to approach and press the response lever

Sucrose pellets can act as a US or a CS depending on how presentations of the pellets are related to other stimuli in the situation

Novelty of Conditioned and Unconditioned Stimuli

• Behavioral impact of stimulus depends on its novelty
• If either the CS or US are familiar, learning occurs more slowly than if the CS or US are novel

The Latent-Inhibition or CS-Preexposure Effect

• Latent-inhibition effect (CS-preexposure effect): If a stimulus is highly familiar, it will not be as effective as a CS than if it were novel
  • Common result: participants are slower to acquire responding because of the CS preexposure
    • CS preexposure disrupts/slows learning
• Similar to habituation
  • Both serve to limit processing and attention to stimuli that are presented without a US
• Theoretical explanation of latent inhibition is that the: CS preexposure reduces attention to the CS

The US-Preexposure Effect

Rats received 80 presentations of one or two types of flavored food pellets for 400 US preexposure trials

• After US preexposure phase, 20 Pavlovian conditioning trials were conducted
• One response lever inserted into the experimental chamber for 10 seconds, followed by bacon pellet
• US-preexposure effect: Conditioning was faster for the lever paired with the novel food than for the lever paired with the familiar food
• This effect has been observed in appetitive conditioning, along with fear conditioning, taste aversion learning, drug conditioning

CS and US Intensity and Salience

• Important stimulus variable for classical conditioning: intensity of the conditioned and unconditioned stimuli

• Effects of stimulation are related to intensity of stimulus input

• Stimulus salience (significance)

  • Stimulus intensity contributes to this
  • A stimulus is more salient if it is more intense
    • Additionally, if it is relevant to biological needs of the organism
  • Can also increase salience of CS to make it more similar to the kinds of stimuli an animal encounters in its natural environment

  Sexual conditioning with quail

  • If a naturalistic CS is used in sexual conditioning, learning happens more quickly, sexual behavior becomes conditioned, learning not as easily interrupted by increasing the CS-US interval

CS-US Relevance, or Belongingness