The timescale and functional form of context-dependence during human value-learning
AbstractThe way humans and other animals represent the values of alternatives can be distorted by inferior alternatives that are immediately available for choice (immediate context); or that were encountered in previous episodes (temporal context). Yet, the extent to which the immediate and temporal context (co-) shape such context-dependent value coding remains unclear. Here, we asked human participants (N = 30) to learn the values associated with three alternatives and to explicitly report their learned values before making binary and ternary choices among the alternatives. We show that context-dependent value coding is evident in the pre-choice value estimates and manifests equally in binary and ternary choices. Accordingly, we conclude that value representations are modulated by the temporal (and not the immediate) context. Interestingly, the functional form of context-dependence we report runs against extant value normalization theories and is best captured by a new memory-based valuation mechanism we propose.