veille

Paradoxical choice and the reinforcing value of information

Abstract

Signals that reduce uncertainty can be valuable because well-informed decision-makers can better align their preferences to opportunities. However, some birds and mammals display an appetite for informative signals that cannot be used to increase returns. We explore the role that reward-predictive stimuli have in fostering such preferences, aiming at distinguishing between two putative underlying mechanisms. The ‘information hypothesis’ proposes that reducing uncertainty is reinforcing per se, somewhat consistently with the concept of curiosity: a motivation to know in the absence of tractable extrinsic benefits. In contrast, the ‘conditioned reinforcement hypothesis’, an associative account, proposes asymmetries in secondarily acquired reinforcement: post-choice stimuli announcing forthcoming rewards (S+) reinforce responses more than stimuli signalling no rewards (S−) inhibit responses. In three treatments, rats faced two equally profitable options delivering food probabilistically after a fixed delay. In the informative option (Info), food or no food was signalled immediately after choice, whereas in the non-informative option (NoInfo) outcomes were uncertain until the delay lapsed. Subjects preferred Info when (1) both outcomes were explicitly signalled by salient auditory cues, (2) only forthcoming food delivery was explicitly signalled, and (3) only the absence of forthcoming reward was explicitly signalled. Acquisition was slower in (3), when food was not explicitly signalled, showing that signals for positive outcomes have a greater influence on the development of preference than signals for negative ones. Our results are consistent with an elaborated conditioned reinforcement account, and with the conjecture that both uncertainty reduction and conditioned reinforcement jointly act to generate preference.

veille

Horses form cross-modal representations of adults and children

Abstract

Recently, research on domestic mammals’ sociocognitive skills toward humans has been prolific, allowing us to better understand the human–animal relationship. For example, horses have been shown to distinguish human beings on the basis of photographs and voices and to have cross-modal mental representations of individual humans and human emotions. This leads to questions such as the extent to which horses can differentiate human attributes such as age. Here, we tested whether horses discriminate human adults from children. In a cross-modal paradigm, we presented 31 female horses with two simultaneous muted videos of a child and an adult saying the same neutral sentence, accompanied by the sound of an adult’s or child’s voice speaking the sentence. The horses looked significantly longer at the videos that were incongruent with the heard voice than at the congruent videos. We conclude that horses can match adults’ and children’s faces and voices cross-modally. Moreover, their heart rates increased during children’s vocalizations but not during adults’. This suggests that in addition to having mental representations of adults and children, horses have a stronger emotional response to children’s voices than adults’ voices.