This chapter explores the relationship between cues and consequences in avoidance learning, focusing on how different stimuli are selected as cues based on the nature of the subsequent reinforcer. The study uses rats to investigate the effectiveness of audiovisual and gustatory stimuli in producing avoidance reactions when paired with electric shock, toxin, or x-ray. Key findings include: 1. **Audiovisual vs. Gustatory Stimuli**: When paired with electric shock, avoidance reactions transfer to the audiovisual stimulus but not the gustatory stimulus. Conversely, when paired with toxin or x-ray, avoidance reactions transfer to the gustatory stimulus but not the audiovisual stimulus. 2. **Reinforcer Nature**: The effectiveness of cues is influenced by the nature of the reinforcer. For example, ionizing radiation and toxins produce strong aversions when paired with distinct flavors, leading to a "conditioned nausea" effect. In contrast, auditory and visual stimuli do not acquire similar properties even when contingent on the licking response. 3. **Immediate vs. Delayed Shock**: Immediate shock produces avoidance reactions that transfer to the audiovisual stimulus but not the gustatory stimulus, while delayed shock has the opposite effect, transferring to the gustatory stimulus. 4. **Conclusion**: The selection of cues is related to the consequences of the reinforcer. Natural selection may have favored mechanisms that associate gustatory and olfactory cues with internal discomfort, as these receptors sample materials soon to be incorporated into the body. The study suggests that the effectiveness of different cues in producing avoidance reactions is influenced by the nature of the reinforcer and the specific response of the organism.This chapter explores the relationship between cues and consequences in avoidance learning, focusing on how different stimuli are selected as cues based on the nature of the subsequent reinforcer. The study uses rats to investigate the effectiveness of audiovisual and gustatory stimuli in producing avoidance reactions when paired with electric shock, toxin, or x-ray. Key findings include: 1. **Audiovisual vs. Gustatory Stimuli**: When paired with electric shock, avoidance reactions transfer to the audiovisual stimulus but not the gustatory stimulus. Conversely, when paired with toxin or x-ray, avoidance reactions transfer to the gustatory stimulus but not the audiovisual stimulus. 2. **Reinforcer Nature**: The effectiveness of cues is influenced by the nature of the reinforcer. For example, ionizing radiation and toxins produce strong aversions when paired with distinct flavors, leading to a "conditioned nausea" effect. In contrast, auditory and visual stimuli do not acquire similar properties even when contingent on the licking response. 3. **Immediate vs. Delayed Shock**: Immediate shock produces avoidance reactions that transfer to the audiovisual stimulus but not the gustatory stimulus, while delayed shock has the opposite effect, transferring to the gustatory stimulus. 4. **Conclusion**: The selection of cues is related to the consequences of the reinforcer. Natural selection may have favored mechanisms that associate gustatory and olfactory cues with internal discomfort, as these receptors sample materials soon to be incorporated into the body. The study suggests that the effectiveness of different cues in producing avoidance reactions is influenced by the nature of the reinforcer and the specific response of the organism.