Forget-me-not: Complex floral displays, inter-signal interactions, and pollinator cognition

Flowers are multisensory displays used by plants to influence the behavior of pollinators. Although we know a great deal about how individual signal components are produced by plants and detected or learned by pollinators, very few experiments directly address the function of floral signal complexity, i.e. how the multicomponent nature of these signals benefits plant or pollinator. Yet, experimental psychology suggests that increasing complexity can enhance subjects' ability to detect, learn and remember stimuli, and the plant's reproductive success depends upon ensuring that pollinators learn their signals and so transport pollen to other similar (conspecific) flowers. Here we explore functional hypotheses for why plants invest in complex floral displays, focusing on hypotheses in which floral signals interact to promote pollinator learning and memory. Specifically, we discuss how an attention-altering or context-providing function of one signal may promote acquisition or recall of a second signal. Although we focus on communication between plants and pollinators, these process-based hypotheses should apply to any situation where a sender benefits from enhancing a receivers acquisition or recall of information [Current Zoology 57 (2): 215-224, 2011].