Biology subjects

Nityananda, V.

Publications and source records attributed to Nityananda, V..

15 recordsLinked to original sources

bioRxiv2026

Binocular visual input is essential for prey capture but not attention to prey in the praying mantis Sphodromantis lineola

Binocular vision provides animals with several evolutionary advantages. In praying mantises, one of these advantages is stereopsis that has different effects while attending to prey and capturing prey. However, the importance of binocular, compared to monocular, visual input has not been tested in either stage of predation. We therefore used an insect 3D cinema to present mantises with binocular and monocular stimuli to either prime their attention or elicit prey capture. We used a previous paradigm where a wide-field figure motion cue attracts mantis attention, which leads to predatory responses to a small-field elementary motion target. We found that binocular visual input enhances attention to cues, but monocular cues are also effective. However, prey capture responses were fundamentally dependent on binocular input. Thus, binocularity appears to be fundamental to prey capture in mantises but not for attending to prey.

animal behavior and cognition↗

bioRxiv2026

Temporal consistency of judgement biases in bumblebees

Judgment bias tasks are increasingly used to assess affective states in animals, yet the extent to which they might reflect transient states or stable traits remains unclear. Here, we tested bumblebees (Bombus terrestris) in an active choice task across three repeated sessions to assess individual consistency in the absence of any manipulation. Bees were trained to associate each of two colours with either a high or a low reward, presented in separate chambers. During testing, they were presented with ambiguous colours. Bees were more likely to choose the high reward chamber and to choose more quickly in response to colours closer to the positive colour. The latency to choose the cues showed significant and moderate repeatability across sessions, suggesting a stable, trait-like underlying component. In contrast, the repeatability of the chamber choices was negligible, indicating that such responses might be largely state-dependent and influenced by situational factors. These findings suggest that judgment biases, particularly as assessed through an active choice task reflect states affected by external factors. Active choice tasks may help disentangle stable behavioural traits from transient affective states in invertebrates.

animal behavior and cognition↗

bioRxiv2025

Acute stress modulates early visual perception and decision-making speed in bees without compromising accuracy

Acute stress is known to influence decision-making, but it can also directly affect earlier stages of sensory processing. In humans, stress alters the perception of basic visual features, fine-tuning vision to support faster responses in threatening contexts. Whether stress induces similar changes in early vision in insects and thus affects visually guided decision-making, remains unknown. Here, we examined how acute stress, simulated via vigorous shaking resembling a predatory attack, affects bumblebees sensitivity thresholds for resolution and contrast sensitivity, two basic visual features, as well as their choice behaviour and decision speed in a dual-choice discrimination task. We found that, similar to humans, stress modulated both thresholds. It increased contrast sensitivity thresholds and shifted spatial frequency thresholds toward finer resolution as well as affecting bee final choice behaviour. Not only were stressed bees more likely to commit to a choice, but they did so significantly faster when their early perceptual decisions were accurate. Collectively, our results suggest that stress reshapes bee visual sensitivity and decision-making not only through an increase in reactivity, but with a flexible shift in decision-making driven by perceptual confidence.

animal behavior and cognition↗

bioRxiv2025

Testing bottom-up cuing effects on target detection and discrimination in Bumblebees

Attention in vertebrates helps prioritise the processing of important sensory information and filter out irrelevant signals. The capture of attention by sudden or salient stimuli typically called bottom-up attention. Little is known about similar attentional process in insects, although they should be advantageous for insects as well. We therefore adapted two paradigms used to investigate bottom-up attention in primates to investigate it in bumblebees: a target detection task and a target discrimination task. For both tasks, we trained bees to choose between two locations on each side of a computer screen and collect a reward bellow a full contrast target displayed on the screen. During detection task tests, the contrast of the target was varied and it could be preceded by a cue flashed on the side of the target, the opposite side of the screen or not flashed at all. The discrimination task tests were similar but with a full contrast target on one side and a variable contrast distractor on the opposite side of the screen. We tested if the presence of the flash influenced the orientation and choices of the bees as well as their contrast sensitivity as has been seen in primates. Our results show no effect of the prior cue, suggesting that other paradigms might prove more useful to test these processes in insects.

animal behavior and cognition↗

bioRxiv2025

Motivational trade-offs as evidence for sentience in bees: a critique

Establishing if insects feel pain can have far-reaching consequences for insect husbandry, commercial pollination and scientific research. Research in this field therefore requires careful experiments and strong evidence. One important criterion proposed for measuring insect sentience is the ability to show a motivational trade-off, in which "the negative value of a noxious or threatening stimulus is weighed (traded-off) against the positive value of an opportunity for reward". A recent paper investigated motivational trade-offs in bumblebees and concluded that bees can trade-off heat against high sugar rewards. In this paper, we develop a signal detection model to highlight which features would be key to supporting the argument that motivational trade-offs are evidence of the capacity for experiencing pain. We then re-analyse the data from the original paper and find several limitations. Our own re-analysis finds no support for the final conclusions made by the paper. We therefore provide recommendations for future studies investigating the ability of insects to feel pain.

animal behavior and cognition↗

bioRxiv2023

Physically stressed bees expect less reward in an active choice judgement bias test

Emotion-like states in animals are commonly assessed using judgment bias tests, which measure responses to ambiguous information. A few studies have recently used these tests to argue for the presence of emotion-like states in insects. However, the results from most of these studies could have other explanations, including changes in motivation and attention. To control for these explanations, we therefore developed a novel judgment bias test, requiring bumblebees to make an active choice indicating their interpretation of ambiguous stimuli. Bumblebees were trained to associate high or low rewards, delivered in two different reward chambers, with distinct colors. Two groups of bees were then physically stressed by shaking or trapping, while the third group served as a control. We subsequently presented the bees with ambiguous colors between the two learnt colors and noted which reward chamber they chose. When presented with ambiguous colors, stressed bees were less likely than control bees to enter the reward chamber previously associated with high reward. We modelled bee behavior using signal detection and drift diffusion models and showed that control bees and stressed bees were, respectively, more likely to respond optimistically and pessimistically to ambiguous cues. The signal detection model further showed that the behavior of stressed bees was explained by a reduction in their prior expectation of high rewards. Our findings thus provide strong evidence for emotion-like states in bees and suggest that their stress-induced pessimistic behavior is explained by a reduced expectation of higher rewards.

animal behavior and cognition↗

bioRxiv2023

Learning modifies attention during bumblebee visual search

The role of visual search during bee foraging is relatively understudied compared to the choices made by bees. As bees learn about rewards, we predicted that visual search would be modified to prioritise rewarding flowers. To test this, we ran an experiment testing how bee search differs in the initial and later part of training as they learn about flowers with either higher-or lower-quality rewards. We then ran an experiment to see how this prior training with reward influences their search on a subsequent task with different flowers. We used the time spent inspecting flowers as a measure of attention and found that learning increased attention to rewards and away from distractors. Higher quality rewards led to decreased attention to non-flower regions, but lower quality rewards did not. Prior experience of lower rewards also led to more attention to higher rewards compared to distractors and non-flower regions. Our results suggest that flowers would elicit differences in bee search behaviour depending on the sugar content of their nectar. They also demonstrate the utility of studying visual search and have important implications for understanding the pollination ecology of flowers with different qualities of reward. Significance StatementStudies investigating how foraging bees learn about reward typically focus on the choices made by the bees. How bees deploy attention and visual search during foraging is less well studied. We analysed flight videos to characterise visual search as bees learn which flowers are rewarding. We found that learning increases the focus of bees on flower regions. We also found that the quality of the reward a flower offers influences how much bees search in non-flower areas. This means that a flower with lower reward attracts less focussed foraging compared to one with a higher reward. Since flowers do differ in floral reward, this has important implications for how focussed pollinators will be on different flowers. Our approach of looking at search behaviour and attention thus advances our understanding of the cognitive ecology of pollination.

animal behavior and cognition↗

bioRxiv2023

Cue Disparity and Visual Selective Attention in Praying Mantises

External cues bias human attention and the perception of subsequent targets. Little is known about how cue properties, such as depth, influence insect attention. One robust cue to depth is stereoscopic disparity, the difference in the position of an object in the views of the two eyes. Praying mantises are known to use disparity to judge the distance to prey and are therefore ideal insect models to investigate its role in attention. We investigated how three cue propertiesposition, duration and stereoscopic disparity affect mantis selective attention towards subsequent targets. We fitted mantises with 3D glasses and presented them with a cue in 2D or in 3D, followed by two 3D stimuli: a high contrast target and a distractor at different contrasts. Our results show that cue position and distractor contrast had the most influence on responses to targets, with no strong effect of disparity. Compared to the Uncued condition, cues in two of our disparity conditions reduced target responses if presented on the opposite side of the screen, when the distractor was absent. The cues affected subsequent selective attention even when they did not themselves attract head saccades, suggesting covert but not overt attention to the cues. Our results show that the position of prior cues can affect mantis selective attention and add further evidence for the complexity of attention-like processes in insects. Summary StatementCue position and, to a lesser extent, disparity affect praying mantises responses to a subsequent target. This adds further evidence for the complexity of attention-like processes in insects.

animal behavior and cognition↗

bioRxiv2021

A Computational Model of Stereoscopic Prey Capture inPraying Mantises

We present a simple model which can account for the stereoscopic sensitivity of praying mantis predatory strikes. The model consists of a single "disparity sensor": a binocular neuron sensitive to stereoscopic disparity and thus to distance from the animal. The model is based closely on the known behavioural and neurophysiological properties of mantis stereopsis. The monocular inputs to the neuron reflect temporal change and are insensitive to contrast sign, making the sensor insensitive to interocular correlation. The monocular receptive fields have a excitatory centre and inhibitory surround, making them tuned to size. The disparity sensor combines inputs from the two eyes linearly, applies a threshold and then an exponent output nonlinearity. The activity of the sensor represents the model mantiss instantaneous probability of striking. We integrate this over the stimulus duration to obtain the expected number of strikes in response to moving targets with different stereoscopic distance, size and vertical disparity. We optimised the parameters of the model so as to bring its predictions into agreement with our empirical data on mean strike rate as a function of stimulus size and distance. The model proves capable of reproducing the relatively broad tuning to size and narrow tuning to stereoscopic distance seen in mantis striking behaviour. The model also displays realistic responses to vertical disparity. Most surprisingly, although the model has only a single centre-surround receptive field in each eye, it displays qualitatively the same interaction between size and distance as we observed in real mantids: the preferred size increases as prey distance increases beyond the preferred distance. We show that this occurs because of a stereoscopic "false match" between the leading edge of the stimulus in one eye and its trailing edge in the other; further work will be required to find whether such false matches occur in real mantises. This is the first image-computable model of insect stereopsis, and reproduces key features of both neurophysiology and striking behaviour.

neuroscience↗

bioRxiv2020

Synchrony of Non-isochronous Signals in an Acoustically Communicating Katydid

The ability to entrain to auditory stimuli has been a powerful method to investigate the comparative rhythm abilities of different animals. While synchrony to regular (isochronous) rhythms is well documented, synchrony to non-isochronous stimuli, with multiple components at unequal time intervals, is rarer. Several katydid species with isochronous calls have been shown to achieve synchrony as part of their natural calling interactions in multi-individual choruses. Yet no study so far has demonstrated synchrony in any insect with a non-isochronous call. Using natural calling behaviour and playback experiments, we investigated acoustic synchrony and the mechanisms underlying it in the katydid species Mecopoda Two Part Caller. This species has a complex non-isochronous call consisting of a long trill followed by two or more chirps. We found that individual males synchronized trills and, to a lesser extent, chirps. Further investigation of trill synchrony showed that timing of trills is modified by external trills but not chirps. Chirp synchrony is modified by external chirps but also by trills. We suggest a two-oscillator model underlying synchrony in this species and discuss the implications for the evolution of acoustic synchrony.

animal behavior and cognition↗

bioRxiv2020

Reward Value Is More Important Than Physical Saliency During Bumblebee Visual Search For Multiple Rewarding Targets

Several animals, including bees, use visual search to distinguish targets of interest and ignore distractors. While bee flower choice is well studied, we know relatively little about how they choose between multiple rewarding flowers in complex floral environments. Two important factors that could influence bee visual search for multiple flowers are the physical saliency (colour contrast against the background) of flowers and the reward value associated with them. We here investigated how these two different factors contribute to bee visual search. We trained bees to independently recognize two rewarding colours that in different experiments differed in either physical saliency, reward value or both. We then measured their choices and attention to these colours in the presence of distractors in a test without reinforcement. We found that bees preferred more salient or higher rewarding flowers and ignored distractors. When the high-reward flowers were less salient than the low-reward flowers, bees were nonetheless equally likely to choose high-reward flowers. Bees were more also more likely to attend to these high-reward flowers, with higher inspection times around them and faster search times when choosing them. When flowers differed in reward, we also found an effect of the training order with low-reward targets being more likely to be chosen if they had been encountered during the more immediate training session prior to the test. Our results parallel recent findings from humans demonstrating that reward value can attract attention even when targets are less salient and irrelevant to the current task.

animal behavior and cognition↗

bioRxiv2018

Motion-in-depth perception and prey capture in the praying mantis

Perceiving motion-in-depth is essential to detecting approaching or receding objects, predators and prey. This can be achieved using several cues, including binocular stereoscopic cues such as changing disparity and interocular velocity differences and monocular cues such as looming. While these have been studied in detail in humans, only looming responses have been well characterized in insects and we know nothing about the role that stereo cues play and how they might interact with looming cues. We used our 3D insect cinema in a series of experiments to investigate the role of the stereo cues mentioned above, as well as looming, in the perception of motion-in-depth during predatory strikes by the praying mantis. Our results show that motion-in-depth does increase the probability of mantis strikes but only for the classic looming stimulus, an expanding luminance edge. Approach indicated by radial motion of a texture or expansion of a motion-defined edge, or by stereoscopic cues, all failed to elicit increased striking. We conclude that mantises use stereopsis to detect depth but not motion-in-depth, which is detected via looming.\n\nSummary StatementBoth stereoscopic visual cues and changing luminance cues can enable detection of approaching objects. We show that mantises use looming rather than stereo cues to detect motion-in-depth.

animal behavior and cognition↗

bioRxiv2018

Apparent Motion Perception in the Praying Mantis: Psychophysics and Modelling

Apparent motion is the perception of a motion created by rapidly presenting still frames in which objects are displaced in space. Observers can reliably discriminate the direction of apparent motion when inter-frame object displacement is below a certain limit, Dmax. Earlier studies of motion perception in humans found that Dmax scales with spatial element size, interpreting the relationship between the two as linear, and that Dmax appears to be lower-bounded at around 15 arcmin. Here, we run corresponding experiments in the praying mantis Sphodromantis lineola to investigate how Dmax scales with element size. We used moving random chequerboard patterns of varying element and displacement step sizes to elicit the optomotor response, a postural stabilization mechanism that causes mantids to lean in the direction of large-field motion. Subsequently, we calculated Dmax as the displacement step size corresponding to a 50% probability of detecting an optomotor response in the same direction as the stimulus. Our main findings are that mantis Dmax appears to scale as a power-law of element size and that, in contrast to humans, it does not appear to be lower-bounded. We present two models to explain these observations: a simple high-level model based on motion energy in the Fourier domain and a more detailed one based on the Reichardt Detector. The models present complementary intuitive and physiologically-realistic accounts of how Dmax scales with element size in insects.\n\nAuthor SummaryComputer monitors, smart phone screens and other forms of digital displays present a series of still images (frames) in which objects are displaced in small steps, tricking us into perceiving smooth motion. This illusion is referred to as \"apparent motion\", and for it to work effectively the magnitude of each displacement step must be smaller than a certain limit, referred to as Dmax. Previous studies have investigated the relationship between this limit and object size in humans and found that larger objects can be displaced in larger steps without affecting motion perception. In this work, we investigated the same relationship in the praying mantis Sphodromantis lineola by presenting them with moving chequerboard patterns on a computer monitor. Even though motion perception in humans and insects are believed to be explained equally well by the same underlying model, we found that Dmax scales with object size differently in mantids. These results suggest that there may be qualitative differences in how mantids perceive apparent motion compared to humans.

neuroscience↗

bioRxiv2017

Contrast Thresholds Reveal Different Visual Masking Functions In Humans And Praying Mantises

Recently, we showed a novel property of the Hassenstein-Reichardt detector: namely, that insect motion detection can be masked by \"invisible\" noise, i.e. visual noise presented at spatial frequencies to which the animals do not respond when presented as a signal. While this study compared the effect of noise on human and insect motion perception, it used different ways of quantifying masking in two species. This was because the human studies measured contrast thresholds, which were too time-consuming to acquire in the insect given the large number of stimulus parameters examined. Here, we run longer experiments in which we obtained contrast thresholds at just two signal and two noise frequencies. We examine the increase in threshold produced by noise at either the same frequency as the signal, or a different frequency. We do this in both humans and praying mantises (Sphodromantis lineola), enabling us to compare these species directly in the same paradigm. Our results confirm our earlier finding: whereas in humans, visual noise masks much more effectively when presented at the signal spatial frequency, in insects, noise is roughly equivalently effective whether presented at the same frequency or a lower frequency. In both species, visual noise presented at a higher spatial frequency is a less effective mask.\n\nSummary StatementWe here show that despite having similar motion detection systems, insects and humans differ in the effect of low and high spatial frequency noise on their contrast thresholds.

neuroscience↗

bioRxiv2017

When invisible noise obscures the signal: the consequences of nonlinearity in motion detection

1The motion energy model is the standard account of motion detection in animals from beetles to humans. Despite this common basis, we show here that a difference in the early stages of visual processing between mammals and insects leads this model to make radically different behavioural predictions. In insects, early filtering is spatially lowpass, which makes the surprising prediction that motion detection can be impaired by \"invisible\" noise, i.e. noise at a spatial frequency that elicits no response when presented on its own as a signal. We confirm this prediction using the optomotor response of praying mantis Sphodromantis lineola. This does not occur in mammals, where spatially bandpass early filtering means that linear systems techniques, such as deriving channel sensitivity from masking functions, remain approximately valid. Counter-intuitive effects such as masking by invisible noise may occur in neural circuits wherever a nonlinearity is followed by a difference operation.

neuroscience↗