Parameters of human evaluative flavor-flavor conditioning

Abstract

In this study, human Ss ( N = 48) were first exposed to a differential evaluative flavor-flavor conditioning schedule, consisting of either 6 or 12 colored CS+ flavor/US compounds and 6 or 12 colored CS− flavor presentations. Two fruit flavors were used as CS+ and CS−, and Tween 20 (Polysorbate 20) was used as a disliked flavor US. The CS− flavor was either presented in plain water or in a moderately positive sugar compound solution. At the moment of testing, visual-analog CS+ and CS− flavor evaluations were obtained in compounds containing the acquisition color, a new color, or no color. The test series was split up in two equivalent logical blocks, allowing to assess the extinction sensitivity of the conditioned flavor valence. A clear acquired evaluative CS+/CS− flavor differentiation was observed when the CS− flavor had been presented in compound with sugar, but only a nonsignificant tendency was obtained when the CS− flavor was presented in plane water. The latter finding was most probably related to the CS−/ water solution not representing a neutral but a mildly negative stimulus. The number of acquisition trials did not influence the size of the conditioning effect, and the test color context did not systematically weaken or strengthen the expression of the acquired evaluative flavor differentiation. Finally, the conditioning effect did not weaken as testing proceeded: An equally strong CS+/CS− differentiation was observed in the second as in the first block of test trials.