• SCR conditioning;
  • Intermittent reinforcement;
  • Reinforcement ratio;
  • Sequential trends;
  • Strength learning;
  • Expectancy;
  • Negative recency;
  • Awareness


To assess some implications of incremental-decremental learning theories for classical conditioning, skin conductance response conditioning in humans was examined as a function of reinforcement schedule. First anticipatory responses (FARs: latency from 1.0 to 3.5 sec after signal onset) were not affected by reinforcement ratio, but, during the first half of training, the probability of second anticipatory responses (SARs: latency from 3.6 to 7.0 sec after signal onset) increased with increases in reinforcement ratio. FAR and SAR probabilities decreased across sequences of successively reinforced trials and increased across sequences of successively nonreinforced trials. These results are incompatible with the theoretical expectation that response likelihood should increase following reinforced trials and decrease following nonreinforced trials. Alternative accounts of the results are discussed.