Enhanced preference for a flavour following reversed flavour—glucose pairing

In two experiments hungry rats showed enhanced preference for a flavour as a result of a procedure whereby the flavour followed presentation of 10% glucose—i.e. the reverse of the usual sequence. This provides the first example of excitatory conditioning resulting from reversed pairing involving an appetitive reinforcer. Experiment 1 compared a Cinnamon group, for which ingestion of glucose was followed after 3 min by cinnamon and on other days water was followed by wintergreen, with a Wintergreen group in which wintergreen followed glucose and cinnamon followed water. In a final 2-bottle test relative preference for cinnamon was greater in the Cinnamon than in the Wintergreen group. This effect was replicated in Experiment 2, which compared an Immediate group, for which, as above, drinking glucose was followed 3 min later by access to cinnamon, with a Delay group, for which there was a delay of 1 hr between glucose and subsequent access to cinnamon. Enhanced preference for cinnamon was found only in the Immediate group and appeared after only four glucose-cinnamon pairings. An important finding came from a choice test between glucose and saccharin in which the Immediate group showed a weaker preference for glucose than the Delay group. This indicated that a novel flavour may overshadow the association between the flavour of glucose and its consequences, which normally serves to enhance preference for glucose.     

Stimulus-Response Compatibility for Vertically Oriented Stimuli and Horizontally Oriented Responses: Evidence for Spatial Coding

It has previously been shown that, when stimuli positioned above or below a central fixation point (“up” and “down” stimuli) are assigned to left and right responses, the stimulus-response mapping up-left/down-right is more compatible than the mapping up-right/down-left for responses executed by the left hand in the left hemispace, but this relation is reversed for responses executed by the right hand in the right hemispace. In Experiment 1, each hand responded at locations in both hemispaces to dissociate the influence of hand identity from response location, and response location was found to be the determinant of relative compatibility. In Experiment 2 responses were made at the sagittal midline, and an inactive response switch was placed to the left or right to induce coding of the active switch as right or left, respectively. This manipulation of relative location had an effect similar to, although of lesser magnitude than, that produced by physically changing location of the response switch in Experiment 1. It is argued that these results are counter to predictions of a movement-preference account and consistent with the view that spatial coding underlies compatibility effects for orthogonally oriented stimulus and response sets.