Food Aversion Learning

During the past 10 years, the study of learned aversions to foods has become one of the most' 'popular" areas of research in animal psychology. Learned aversions to foods are typically produced in the laboratory by first allowing an animal to eat (or drink) some distinctively novel substance and then making the animal' 'ill" in some way, most frequently by either giving it an injection of some "illness" -producing drug such as lithium chloride or by exposing it to a toxic dose of radiation. When an animal that has been treated in this way is subsequently given another opportunity to ingest the same or a similar substance, one usually observes that it will either totally avoid ingesting the substance or that it will consume less of it than a control animal that was not made ill after previously consuming the same substance. This form of learning has attracted the interest of many researchers because there are two apparently striking differences in the acquisition of food aversions and the acquisition of other types of associative learning.

1 Learning as a General Process with an Emphasis on Data from Feeding Experiments.- 1. Deficiencies of Traditional Learning Theories.- 1.1. Behaviorism.- 1.2. Tabula Rasa.- 1.3. Effects of the Falsity of Traditional Assumptions.- 2. Neoevolutionary Learning Theories.- 2.1. The Adaptive Complex.- 2.2. Are General Laws of Learning Unimportant?.- 2.3. Traditional Preconceptions in Neoevolutionary Theory.- 2.4. Evolutionary Principles and Prediction.- 3. Food Aversion Learning Governed by a General Process.- 3.1. Parametric Effects.- 3.2. Relative Cue Validities.- 3.3. Conditioned Inhibition.- 3.4. Sensory Preconditioning.- 3.5. The Delay Problem.- 3.6. Crossvalidation: General Processes Explain Another Anomaly.- 4. The Epistemic Part of the General Learning Process.- 4.1. Rationalization for a Lack of Precision.- 4.2. The Epistemic Process in Action.- 4.3. Speculations about Some Factors in Learning.- 4.4. Relevance Principles.- 4.5. The Integrative Action of the Concurrent Interference Principle.- 5. References.- Appendix to Chapter 1 Interference with Progress by the Scientific Establishment: Examples from Flavor Aversion Learning.- 1. Specific Criticisms.- 1.1. Pseudoconditioning.- 1.2. Temporal Contiguity.- 2. Type-2 Incompetence.- 2.1. Sociology of T2.- 2.2. How T2 Is Hidden.- 2.3. Society and T2.- 3. A Modest Proposal.- 4. References.- 2 Biological Significance of Food Aversion Learning.- 1. The “Learning-as-a-General-Process” Assumption.- 1.1. Evolutionary Specializations in Learning.- 1.2. Food Aversion Learning vs. Other Types of Learning.- 1.3. So What?.- 2. Are the Specialized Features of Food Aversion Learning Adaptive?.- 3. Does Our Understanding of Food Aversion Learning Have Implications Regarding the Mechanisms of Learning in Other Situations?.- 3.1. Possible Mechanisms of Long-Delay Learning.- 3.2. Learned Safety.- 3.3. Conclusions.- 4. References.- 3 Stimulus Characteristics in Food Aversion Learning.- 1. Sensory Modalities.- 1.1. Taste.- 1.2. Olfactory Stimuli.- 1.3. Visual-Auditory Stimuli.- 1.4. Somatosensory Stimuli.- 2. Parameters of Taste.- 2.1. Quantitative Considerations.- 2.2. Novelty.- 3. Species Differences.- 4. References.- 4 Gustatory Avoidance Conditioning by Drugs of Abuse: Relationships to General Issues in Research on Drug Dependence.- 1. Some General Issues.- 1.1. Effective Drugs.- 1.2. Toxicity and Effectiveness.- 1.3. Paradox or Not?.- 2. Studies of Mechanism: How Does the UCS Work?.- 2.1. Central Versus Peripheral Locus of Effect.- 2.2. A Nonspecific Mechanism: Novelty.- 2.3. The Importance of UCS Duration.- 3. An Area of Conflict: Interpreting the Effects of Prior Exposure to the UCS on Subsequent Conditioning.- 3.1. Prior Exposure to Morphine: The “Artificial Need” Hypothesis.- 3.2. The Tolerance Hypothesis.- 3.3. Habituation to Novelty.- 3.4. Associative Mechanisms.- 3.5. Conclusions.- 4. Summing Up.- 5. References.- 5 Suppression of Interspecific Aggression Using Toxic Reinforcers.- 1. Introduction.- 2. Muricide, the Mouse-Killing Response of Rats.- 2.1. Effects of Postkill Injections of Toxic Chemicals.- 2.2. Dissociation of Killing and Eating.- 2.3. Comparison with an Exteroceptive Reinforcer—Foot Shock.- 2.4. Summary and Implications.- 3. Some Species Differences: Suppression of Interspecific Aggression by Food Aversions in Predatory Species.- 3.1. The Relation between Killing and Eating in Organisms that Capture and Feed.- 3.2. Suppression of Predation in True Predators.- 3.3. A Two-Phase Hypothesis.- 3.4. The Origin of Species Differences.- 4. Conclusions.- 5. References.- 6 Koalas, Men, and Other Conditioned Gastronomes.- 1. Naturalistic and Anthropological Observations on Diet Selection.- 1.1. The Problem of the Infant Koala Bear.- 1.2. Historic Notes on Man’s Feeding Habits.- 2. Experience and Taste Preference.- 2.1. Prenatal and Infant Influences.- 2.2. Neonatal Experience and Diet Selection.- 2.3. Dietary Selection and the “Medicine” Effect.- 3. Neural Structure and Feeding Function.- 3.1. Central Regulators and Gut Sensors.- 3.2. Palatability and Visceral Feedback.- 4. Summary: The Prototypical Gastronome.- 5. References.- 7 Physiological Mechanisms of Conditioned Food Aversion.- 1. Introduction.- 2. Functional Organization of CFA Circuits.- 2.1. CS and UCS Processing.- 2.2. Cortical Level.- 2.3. Subcortical Centers.- 3. ECS Studies.- 3.1. Short-Term Memory and Consolidation.- 3.2. Metrazol.- 3.3. Repeated ECS Treatment.- 4. Drug Effects.- 4.1. Drugs as UCS.- 4.2. Effects on CTA Acquisition.- 4.3. Effects on CTA Retrieval.- 4.4. Experiments with Intravascular Taste.- 5. Developmental Studies.- 6. Electrophysiological Analysis.- 6.1. Gustatory Control of Licking.- 6.2. EEG Correlates of CTA.- 6.3. Unit Activity Correlates of CTA.- 7. Conclusions.- 8. References.