Research concerned with visual dominance in appetitive and auditory dominance in aversive learning situations (selective associations) is reviewed. The present analysis stresses that the dominant sensory modality of stimulus control is determined by the relative affective valence acquired by a compound auditory-visual stimulus through reinforcement contingencies, rather than by whether the primary reinforcer is appetitive or aversive. For example, take two groups of rats or pigeons on exactly the same shock-avoidance contingency in a tone-light compound (TL), but with different contingencies when the compound is absent (TL). Responding came predominantly under (1) auditory control when conditions in TL were hedonically negative relative to those in (TL), and (2) visual control when conditions in (TL) made TL relatively positive. Selective associations here are a product of the relative hedonic state, positive or negative, established to the auditory-visual compound. Therefore, this constraint reflects a high level of functioning by a hedonic comparator -- with TL’s hedonic value contextually determined by the totality of the events encountered, and reinforcement contingencies, operating in its world. The physical particulars of the reinforcer in TL here, shock avoidance, clearly were not responsible for the hedonic psychological state TL produced. Weiss, Panlilio, and Schindler (1993a, 1993b) went on to show that these proclivities can be (1) reversed, and (2) overcome by a blocking design when the biologically-contingency-disadvantaged stimulus is first pretrained on its own. Relating the “hedonic model” to evolution is speculative. But, the hedonic model is scientifically integrative by relating this biological constraint to a variety of phenomena that involve incentive-motivational states. These include choice behavior, conditioned preference, behavioral contrast and appetitive-aversive interactions.