Noisy communities and signal detection: why do foragers visit rewardless flowers?

Floral communities present complex and shifting resource landscapes for flower-foraging animals. Strong similarities among the floral displays of different plant species, paired with high variability in reward distributions across time and space, can weaken correlations between floral signals and reward status. As a result, it should be difficult for foragers to discriminate between rewarding and rewardless flowers. Building on signal detection theory in behavioural ecology, we use hypothetical probability density functions to examine graphically how plant signals pose challenges to forager decision-making. We argue that foraging costs associated with incorrect acceptance of rewardless flowers and incorrect rejection of rewarding ones interact with community-level reward availability to determine the extent to which rewardless and rewarding species should overlap in flowering time. We discuss the evolutionary consequences of these phenomena from both the forager and the plant perspectives. This article is part of the theme issue ‘Signal detection theory in recognition systems: from evolving models to experimental tests’.

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Signal detection: applying analysis methods from psychology to animal behaviour

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2019.0480 ◽

2020 ◽

Vol 375 (1802) ◽

pp. 20190480 ◽

Cited By ~ 1

Author(s):

Christian J. Sumner ◽

Seirian Sumner

Keyword(s):

Signal Detection ◽

Signal Detection Theory ◽

Sensory Information ◽

Experimental Tests ◽

Detection Theory ◽

Animal Behaviour ◽

Laboratory Animals ◽

Natural Environments ◽

Recognition Systems ◽

Psychological Studies

Conspecific acceptance thresholds (Reeve 1989 Am. Nat. 133 , 407–435), which have been widely applied to explain ecological behaviour in animals, proposed how sensory information, prior information and the costs of decisions determine actions. Signal detection theory (Green & Swets 1966 Signal detection theory and psychophysics ; SDT), which forms the basis of CAT models, has been widely used in psychological studies to partition the ability to discriminate sensory information from the action made as a result of it. In this article, we will review the application of SDT in interpreting the behaviour of laboratory animals trained in operant conditioning tasks and then consider its potential in ecological studies of animal behaviour in natural environments. Focusing on the nest-mate recognition systems exhibited by social insects, we show how the quantitative application of SDT has the potential to transform acceptance rate data into independent indices of cue sensitivity and decision criterion (also known as the acceptance threshold). However, further tests of the assumptions underlying SDT analysis are required. Overall, we argue that SDT, as conventionally applied in psychological studies, may provide clearer insights into the mechanistic basis of decision making and information processing in behavioural ecology. This article is part of the theme issue ‘Signal detection theory in recognition systems: from evolving models to experimental tests’.

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The evolution of conspecific acceptance threshold models

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2019.0475 ◽

2020 ◽

Vol 375 (1802) ◽

pp. 20190475 ◽

Cited By ~ 1

Author(s):

Hannah M. Scharf ◽

Andrew V. Suarez ◽

H. Kern Reeve ◽

Mark E. Hauber

Keyword(s):

Signal Detection ◽

Signal Detection Theory ◽

Empirical Support ◽

Experimental Tests ◽

Detection Theory ◽

Threshold Models ◽

Acceptance Threshold ◽

Systems Research ◽

Recognition Systems ◽

Recognition Errors

How do organisms balance different types of recognition errors when cues associated with desirable and undesirable individuals or resources overlap? This is a fundamental question of signal detection theory (SDT). As applied in sociobiology, SDT is not limited to a single context or animal taxon, therefore its application can span what may be considered dissimilar systems. One of the applications of SDT is the suite of acceptance threshold models proposed by Reeve (1989), which analysed how individuals should balance acceptance and rejection errors in social discrimination decisions across a variety of recognition contexts, distinguished by how these costs and benefits relatively combine. We conducted a literature review to evaluate whether these models' specific predictions have been upheld. By examining over 350 research papers, we quantify how Reeve's models (Reeve 1989 Am. Nat. 133 , 407–435 ( doi:10.1086/284926 )) have influenced the field of ecological and behavioural recognition systems research. We found overall empirical support for the predictions of the specific models proposed by Reeve, and argue for further expansion of their applications into more diverse taxonomic and additional recognition contexts. This article is part of the theme issue ‘Signal detection theory in recognition systems: from evolving models to experimental tests’.

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Individual vocal recognition across taxa: a review of the literature and a look into the future

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2019.0479 ◽

2020 ◽

Vol 375 (1802) ◽

pp. 20190479 ◽

Cited By ~ 2

Author(s):

Nora V. Carlson ◽

E. McKenna Kelly ◽

Iain Couzin

Keyword(s):

Signal Detection ◽

Signal Detection Theory ◽

Experimental Tests ◽

Mate Recognition ◽

Review Of The Literature ◽

Theme Issue ◽

Animal Kingdom ◽

Vocal Recognition ◽

Recognition Systems ◽

Evolving Models

Individual vocal recognition (IVR) has been well studied in mammals and birds. These studies have primarily delved into understanding IVR in specific limited contexts (e.g. parent–offspring and mate recognition) where individuals discriminate one individual from all others. However, little research has examined IVR in more socially demanding circumstances, such as when an individual discriminates all individuals in their social or familial group apart. In this review, we describe what IVR is and suggest splitting studies of IVR into two general types based on what questions they answer (IVR-singular, and IVR-multiple). We explain how we currently test for IVR, and many of the benefits and drawbacks of different methods. We address why IVR is so prevalent in the animal kingdom, and the circumstances in which it is often found. Finally, we explain current weaknesses in IVR research including temporality, specificity, and taxonomic bias, and testing paradigms, and provide some solutions to address these weaknesses. This article is part of the theme issue ‘Signal detection theory in recognition systems: from evolving models to experimental tests’.

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Sensory bias and signal detection trade-offs maintain intersexual floral mimicry

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2019.0469 ◽

2020 ◽

Vol 375 (1802) ◽

pp. 20190469 ◽

Cited By ~ 1

Author(s):

Avery L. Russell ◽

David W. Kikuchi ◽

Noah W. Giebink ◽

Daniel R. Papaj

Keyword(s):

Signal Detection ◽

Signal Detection Theory ◽

Experimental Tests ◽

Detection Theory ◽

Perceptual Bias ◽

Batesian Mimicry ◽

Interspecies Interactions ◽

Floral Mimicry ◽

Trade Offs ◽

Male Flowers

Mimicry is common in interspecies interactions, yet conditions maintaining Batesian mimicry have been primarily tested in predator–prey interactions. In pollination mutualisms, floral mimetic signals thought to dupe animals into pollinating unrewarding flowers are widespread (greater than 32 plant families). Yet whether animals learn to both correctly identify floral models and reject floral mimics and whether these responses are frequency-dependent is not well understood. We tested how learning affected the effectiveness and frequency-dependence of imperfect Batesian mimicry among flowers using the generalist bumblebee, Bombus impatiens , visiting Begonia odorata , a plant species exhibiting intersexual floral mimicry. Unrewarding female flowers are mimics of pollen-rewarding male flowers (models), though mimicry to the human eye is imperfect. Flower-naive bees exhibited a perceptual bias for mimics over models, but rapidly learned to avoid mimics. Surprisingly, altering the frequency of models and mimics only marginally shaped responses by naive bees and by bees experienced with the distribution and frequency of models and mimics. Our results provide evidence both of exploitation by the plant of signal detection trade-offs in bees and of resistance by the bees, via learning, to this exploitation. Critically, we provide experimental evidence that imperfect Batesian mimicry can be adaptive and, in contrast with expectations of signal detection theory, functions largely independently of the model and mimic frequency. This article is part of the theme issue ‘Signal detection theory in recognition systems: from evolving models to experimental tests’.

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The signal detection problem of aposematic prey revisited: integrating prior social and personal experience

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2019.0473 ◽

2020 ◽

Vol 375 (1802) ◽

pp. 20190473 ◽

Cited By ~ 1

Author(s):

Liisa Hämäläinen ◽

Rose Thorogood

Keyword(s):

Signal Detection ◽

Signal Detection Theory ◽

Personal Information ◽

Social Information ◽

Natural Populations ◽

Parus Major ◽

Experimental Tests ◽

Detection Theory ◽

Personal Sampling ◽

Predator Learning

Ever since Alfred R. Wallace suggested brightly coloured, toxic insects warn predators about their unprofitability, evolutionary biologists have searched for an explanation of how these aposematic prey evolve and are maintained in natural populations. Understanding how predators learn about this widespread prey defence is fundamental to addressing the problem, yet individuals differ in their foraging decisions and the predominant application of associative learning theory largely ignores predators' foraging context. Here we revisit the suggestion made 15 years ago that signal detection theory provides a useful framework to model predator learning by emphasizing the integration of prior information into predation decisions. Using multiple experiments where we modified the availability of social information using video playback, we show that personal information (sampling aposematic prey) improves how predators (great tits, Parus major ) discriminate between novel aposematic and cryptic prey. However, this relationship was not linear and beyond a certain point personal encounters with aposematic prey were no longer informative for prey discrimination. Social information about prey unpalatability reduced attacks on aposematic prey across learning trials, but it did not influence the relationship between personal sampling and discrimination. Our results suggest therefore that acquiring social information does not influence the value of personal information, but more experiments are needed to manipulate pay-offs and disentangle whether information sources affect response thresholds or change discrimination. This article is part of the theme issue ‘Signal detection theory in recognition systems: from evolving models to experimental tests’.

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Discriminating between similar alarm calls of contrasting function

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2019.0474 ◽

2020 ◽

Vol 375 (1802) ◽

pp. 20190474 ◽

Cited By ~ 1

Author(s):

Natalie T. Tegtman ◽

Robert D. Magrath

Keyword(s):

Signal Detection ◽

Signal Detection Theory ◽

Experimental Tests ◽

Detection Theory ◽

Alarm Calls ◽

Signal Design ◽

Contextual Cues ◽

Trade Off ◽

Signal Features ◽

Malurus Cyaneus

In a pioneering study of signal design, Marler (Marler 1955 Nature 176 , 6–8. ( doi:10.1038/176006a0 ); Marler 1957 Behaviour 11 , 13–37. ( doi:10.1163/156853956X00066 )) argued that the contrasting acoustic design of hawk (seet) and mobbing alarm calls of European passerines reflected their contrasting function. Hawk alarms were high-frequency tones, warning conspecifics to flee but making localization difficult for predators, while mobbing calls were broadband and harsh, allowing easy localization and approach. Contrasting signal features are also consistent with signal detection theory. Discriminating these calls quickly is critical for survival, because hawk alarms require immediate escape. These signals should therefore be selected to be easy to discriminate, reducing the trade-off between immediate fleeing to hawk alarms and unnecessary fleeing to mobbing alarms. Despite these expectations, hawk and mobbing alarm calls of superb fairy-wrens, Malurus cyaneus , are surprisingly similar, raising the question of discriminability without contextual cues. We synthesized these calls on computer, made intermediates and used playbacks to test whether calls can be discriminated acoustically, and if so by what features. We found that birds used multiple acoustic features when discriminating calls, allowing fast discrimination despite overlap in individual parameters. We speculate that the similarity of fairy-wren alarm calls could enhance detectability of both signals, while multiple subtle acoustic differences reduce a trade-off with discriminability. This article is part of the theme issue ‘Signal detection theory in recognition systems: from evolving models to experimental tests'.

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