Optimal multisensory integration

Abstract

Animals are often confronted with potentially informative stimuli from a variety of sensory modalities. Although there is a large proximate literature demonstrating multisensory integration, no general framework explains why animals integrate. We developed and tested a quantitative model that explains why multisensory integration is not always adaptive and explains why unimodal decision-making might be favored over multisensory integration. We present our model in terms of a prey that must determine the presence or absence of a predator. A greater chance of encountering a predator, a greater benefit of correctly responding to a predator, a lower benefit of correctly foraging, or a greater uncertainty of the second stimulus favors integration. Uncertainty of the first stimulus may either increase or decrease the favorability of integration. In three field studies, we demonstrate how our model can be empirically tested. We evaluated the model with field studies of yellow-bellied marmots (Marmota flaviventer) by presenting marmots with an olfactory-acoustic predator stimulus at a feed station. We found some support for the model's prediction that integration is favored when the second stimulus is less noisy. We hope additional predictions of the model will guide future empirical work that seeks to understand the extent to which multimodal integration might be situation dependent. We suggest that the model is generalizable beyond antipredator contexts and can be applied within or between individuals, populations, or species. Multisensory integration is often studied from a very proximate view that simply describes the process of integration. We developed a model, the first of its kind, to investigate the situations under which multisensory integration is adaptive. We empirically evaluated the model by investigating the conditions under which yellow-bellied marmots integrated predatory scents and sounds. We found that integration can depend on an animal's situation at a given point in time.

Visual cues of predation risk outweigh acoustic cues: a field experiment in black-capped chickadees

“…Prey can use a variety of cues to evaluate current predation risk, and recently attention has shifted towards understanding how and under what circumstances they should integrate cues across different sensory modalities [8,12]. We studied how chickadees respond to two types of cues of predation danger (visual and acoustic) that vary in the degree of certainty, and how combining these cues shapes foraging decisions.…”

“…More recently, studies have begun to address how and under what circumstances prey might combine cues from multiple sensory modalities to improve their estimation of current predation risk [8,12]. The decision to respond to a cue or not is expected to depend on the level of reliability of the cue in relation to the level of uncertainty in the environment [8,[13][14][15].…”

“…In addition, the way that foragers adjust their behaviour in relation to their degree of certainty about current predation risk may be mediated by energetic constraints. Information received through different modalities will act in combination with environmental gradients to shape optimal decisionmaking [12,16]. Under conditions where foragers have a low risk of mortality due to starvation (e.g.…”

Are giant clams (Tridacna maxima) distractible? A multi-modal study

“…In honeybees, different olfactory stimuli are processed through different clusters of glomeruli, enabling them to process different components of odor through different pathways (Abel, Rybak & Menzel, 2001;Kirschner et al, 2006). The majority of these previous studies have focused on multi-attribute signaling and not strictly multi-attribute risk assessment (Munoz & Blumstein, 2012;Munoz & Blumstein, 2019). In addition, these previous studies focused mainly on terrestrial organisms; more studies are needed on multi-attribute stimulus assessment in marine organisms.…”

“…Multimodal assessment may provide more information about threats and hence reduce uncertainty about risk leading to an increase or decrease in anti-predator responses (Munoz & Blumstein, 2012). Most multimodal research has explored the additive effect of multiple stimuli as a multisensory experience (Munoz & Blumstein, 2012;Munoz & Blumstein, 2019). Whereas a combination of sound and flow will indeed be considered multimodal, giant clams experience changes in water particle motion through a single sensory channel: their palps.…”