Exposing rats to an upshift from a small reward to a larger reward sometimes yields evidence of consummatory successive positive contrast (cSPC), an effect that could be a suitable animal model of positive emotion. However, cSPC is an unreliable effect. Ten experiments explored the effects of an upshift in sucrose or saccharin concentration on consummatory behavior under several conditions. There was occasional evidence of cSPC, but mostly a combination of increased consummatory behavior relative to preshift reward concentrations and a reduced behavioral level relative to unshifted controls. Such a pattern is consistent with processes causing opposite changes on behavior. Reward upshift may induce processes that suppress behavior, such as taste neophobia (induced by an intense sucrose taste) and generalization decrement (induced by novelty in reward conditions after the upshift). An experiment tested the role of such novelty-related effects by preexposing animals to either the upshift concentration (12% sucrose) or water during three days before the start of the experiment. Sucrose-preexposed animals drank significantly more than water-preexposed animals during the upshift, but just as much as unshifted controls (i.e., no evidence of cSPC). These results suggest that cSPC may be difficult to obtain reliably because reward upshift induces opposing processes. However, they also seriously question the ontological status of cSPC.
|Number of pages||14|
|State||Published - Aug 1 2016|
Bibliographical noteFunding Information:
The authors thank the TCU biopsychology research group for extensive discussions on the topic of successive positive contrast. Gaby Aguilar and Brandon Grant assisted with animal care in some of the experiments reported here. I. Annicchiarico was supported from a scholarship from Fulbright/COLCIENCIAS, Colombia . Participation of L. Cuenya was partially supported by a grant from Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina . Participation of K. Kawasaki was supported by a Sabbatical grant from Hoshi University, Japan . The research reported in this article was partially supported by TCU/SERC Grant 130125 and carried out with IACUC approval in an USDA-inspected research facility.
© 2016 Elsevier B.V..
- Consummatory successive positive contrast
- Generalization decrement
- Incentive relativity
ASJC Scopus subject areas
- Animal Science and Zoology
- Behavioral Neuroscience