High-contrast Stimuli Research Articles

Meeting another's gaze shortens subjective time by capturing attention

Gaze directed at the observer (direct gaze) is an important and highly salient social signal with multiple effects on cognitive processes and behavior. It is disputed whether the effect of direct gaze is caused by attentional capture or increased arousal. Time estimation may provide an answer because attentional capture predicts an underestimation of time whereas arousal predicts an overestimation. In a temporal bisection task, observers were required to classify the duration of a stimulus as short or long. Stimulus duration was selected randomly between 988 and 1479 ms. When gaze was directed at the observer, participants underestimated stimulus duration, suggesting that effects of direct gaze are caused by attentional capture, not increased arousal. Critically, this effect was limited to dynamic stimuli where gaze appeared to move toward the participant. The underestimation was present with stimuli showing a full face, but also with stimuli showing only the eye region, inverted faces and high-contrast eye-like stimuli. However, it was absent with static pictures of full faces and dynamic nonfigurative stimuli. Because the effect of direct gaze depended on motion, which is common in naturalistic scenes, more consideration needs to be given to the ecological validity of stimuli in the study of social attention.

Pictorial low-level features in mental images: evidence from eye fixations.

It is known that eye movements during object imagery reflect areas visited during encoding. But will eye movements also reflect pictorial low-level features of imagined stimuli? In this paper, three experiments are reported in which we investigate whether low-level properties of mental images elicit specific eye movements. Based on the conceptualization of mental images as depictive representations, we expected low-level visual features to influence eye fixations during mental imagery, in the absence of a visual input. In a first experiment, twenty-five participants performed a visual imagery task with high vs. low spatial frequency and high vs. low contrast gratings. We found that both during visual perception and during mental imagery, first fixations were more often allocated to the low spatial frequency-high contrast grating, thus showing that eye fixations were influenced not only by physical properties of visual stimuli but also by its imagined counterpart. In a second experiment, twenty-two participants imagined high contrast and low contrast stimuli that they had not encoded before. Again, participants allocated more fixations to the high contrast mental images than to the low contrast mental images. In a third experiment, we ruled out task difficulty as confounding variable. Our results reveal that low-level visual features are represented in the mind's eye and thus, they contribute to the characterization of mental images in terms of how much perceptual information is re-instantiated during mental imagery.

Children and monkeys overestimate the size of high-contrast stimuli.

The letter height superiority effect reveals that human adults judge letters to be taller than identically sized pseudoletters. This effect extends to words, such that words are estimated to be greater in size or lasting longer in duration than pseudowords of the same size or those presented for the same duration. The physical properties of letters and words also impact their perceived size, such that higher contrast between figure-ground stimuli leads to greater size estimates. Specifically, black letters on a white background (high contrast between figure and ground) are judged to be taller than gray letters and gray pseudoletters on a white background (low contrast between figure and ground) for adult humans. In the current study, we assessed whether this effect would extend to nonverbal stimuli (shapes) such that high-contrast shapes would lead to greater size estimates relative to low-contrast shapes for human children and rhesus monkeys in a two-choice discrimination task. We found that children and monkeys tended to overestimate the size of high-contrast shapes relative to low-contrast shapes consistent with results reported among human adults. Implications for perceptual fluency and its impact on subjective size estimates are discussed.

Effect of blue-blocking lenses on colour contrast sensitivity

ABSTRACT Clinical relevance There is a significant unintended consequences of blue‐blocking lenses on visual behaviour, particularly for the detection of colour. Optometrists need to be mindful of this when prescribing the appropriate blue‐blocking lenses for individuals who work in environments in which blue light is prevalent. Background The selective reduction in visible wavelengths transmitted through commercially available blue‐blocking lenses is known to influence object appearance and luminance contrast, and also potentially object colour contrast. The present study investigated the effect of a number of commercially available blue‐blocking lenses on colour contrast sensitivity in normal individuals under low and high contrast stimulus conditions. Methods Five healthy participants (one man and four women), aged between 23 and 39-years, were recruited for this study. Crizal Prevencia (Essilor), Blue Guardian (Opticare), and Blu‐OLP (GenOp) lenses were examined in this study in comparison to a control lens (clear lens without blue‐filtering coating). In Experiment 1, colour contrast thresholds were measured using a visual search colour detection task in which the colour (CIE Lu'v' red, green, blue and yellow) of the target circle stimulus (randomly located in an annulus of achromatic circles) was systematically reduced using a staircase procedure. As blue‐blocking lenses selectively block blue light, in Experiment 2, colour contrast thresholds were specifically quantified for a range of short wavelengths near the attenuation transmittance range of the blue‐blocking lenses tested. Results Experiments 1 and 2 showed that colour contrast was impaired only for blue colours, and this was most evident at low contrasts. Additionally, the blue‐blocking lenses with lower transmittance profiles led to greater reductions in colour contrast sensitivity and shown to affect colour contrast thresholds. Conclusion Our results suggest that while reducing blue light potentially minimises the harmful effect of blue hazard light, blue‐blocking lenses can unintentionally reduce colour contrast sensitivity, particularly at low light levels.

Neural markers of suppression in impaired binocular vision

Even after conventional patching treatment, individuals with a history of amblyopia typically lack good stereo vision. This is often attributed to atypical suppression between the eyes, yet the specific mechanism is still unclear. Guided by computational models of binocular vision, we tested explicit predictions about how neural responses to contrast might differ in individuals with impaired binocular vision. Participants with a history of amblyopia (N = 25), and control participants with typical visual development (N = 19) took part in the study. Neural responses to different combinations of contrast in the left and right eyes, were measured using both electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Stimuli were sinusoidal gratings with a spatial frequency of 3c/deg, flickering at 4 Hz. In the fMRI experiment, we also ran population receptive field and retinotopic mapping sequences, and a phase-encoded localiser stimulus, to identify voxels in primary visual cortex (V1) sensitive to the main stimulus. Neural responses in both modalities increased monotonically with stimulus contrast. When measured with EEG, responses were attenuated in the weaker eye, consistent with a fixed tonic suppression of that eye. When measured with fMRI, a low contrast stimulus in the weaker eye substantially reduced the response to a high contrast stimulus in the stronger eye. This effect was stronger than when the stimulus-eye pairings were reversed, consistent with unbalanced dynamic suppression between the eyes. Measuring neural responses using different methods leads to different conclusions about visual differences in individuals with impaired binocular vision. Both of the atypical suppression effects may relate to binocular perceptual deficits, e.g. in stereopsis, and we anticipate that these measures could be informative for monitoring the progress of treatments aimed at recovering binocular vision.

Modeling the temporal dynamics of neural responses in human visual cortex

Cortical responses to visual stimuli exhibit complex temporal dynamics, including sub-additive temporal summation, response reduction with repeated or sustained stimuli (adaptation), and slower dynamics at low contrast. Multiple computational models have been proposed to account for these dynamics in several measurement domains, including single-cell recordings, psychophysics, and fMRI. It is challenging to compare these models because there are differences in model form, test stimuli, and instrument. Here we present a new dataset that is well-suited to compare models of neural temporal dynamics. The dataset is from electrocorticographic (ECoG) recordings of human visual cortex, which measures cortical neural population responses with high spatial and temporal precision. The stimuli were large, static contrast patterns and varied systematically in contrast, duration, and inter-stimulus interval (ISI). Time-varying broadband responses were computed using the power envelope of the band-pass filtered voltage time course (50-170 Hz) recorded from a total of 126 electrodes in ten epilepsy patients, covering earlier (V1-V4) and higher-order (LO, TO, IPS) retinotopic maps. In all visual regions, the ECoG broadband responses show several non-linear features: peak response amplitude saturates with high contrast and long stimulus durations; response latency decreases with increasing contrast; and the response to a second stimulus is suppressed for short ISIs and recovers for longer ISIs. These features were well predicted by a computational model (Zhou, Benson, Kay and Winawer, 2019) comprised of a small set of canonical neuronal operations: linear filtering, rectification, exponentiation, and a delayed divisive gain control. These results demonstrate that a simple computational model comprised of canonical neuronal computations captures a wide range of temporal and contrast-dependent neuronal dynamics at millisecond resolution. Finally, we present a software repository that implements models of temporal dynamics in a modular fashion, enabling the comparison of many models fit to the same data and analyzed with the same methods.

Potential employment of transcranial magnetic stimulation as a beneficial intervention in children with amblyopia: a brief overview

Amblyopia is an early functional imbalance between each eye and the brain that may result in visual cortex inhibition. Current conservative treatments involve altering the input from the ‘good eye’, for example, using patching or biochemical penalization. Direct brain stimulation to the amblyopic cortex might improve the condition. This paper aimed to systematically review the published scientific literature regarding the use of transcranial magnetic stimulation (TMS) as a potential method for treatment in the amblyopic visual cortex. This study was a systematic review of the published scientific literature related to theTMS for the treatment of amblyopia that was performed using “TMS, amblyopia” as keywords. However, only three research papers were found and included in the literature review. A study showed that repetitive TMS of the visual cortex can temporarily improve contrast sensitivity in the amblyopic visual cortex. Another study used continuous thetaburst stimulation (cTBS) delivered to the visual cortex while patients viewed a high contrast stimulus with their non-amblyopic eye. It was found that daily theta burst TMS stimulation improved amblyopic eye contrast sensitivity in five adult volunteers. The TMS also increased median visual acuity in the patient with amblyopia after stimulation with no significant changes in the placebo group.Protocol employing repetitive administration of TMS might result in beneficial effects in amblyopia treatment. TMS works in brain dynamics and experience-dependent plasticity, all of which could be important in investigating and treating amblyopia.

Limits of subjective and objective vection for ultra-high frame rate visual displays

Large-field optic flow generates the illusory percept of self-motion, termed ‘vection’. Smoother visual motion displays generate a more compelling subjective sense of vection and objective postural responses, as well as a greater sense of immersiveness for the user observing the visual display. Research suggests that the function linking frame rate and vection asymptotes at 60 frames per second (FPS), but previous studies have used only moderate frame rates that do not approach the limits of human perception. Here, we measure vection using subjective and objective (mean frequency and path length of postural centre-of-pressure (COP) excursions) responses following the presentation of high-contrast optic flow stimuli at slow and fast speeds and low and ultra-high frame rates. We achieve this using a novel rendering method implemented with a projector capable of sub-millisecond temporal resolution in order to simulate refresh rates ranging from very low (15 FPS) to ultra-high frame rates (480 FPS). The results suggest that subjective vection was experienced most strongly at 60 FPS. Below and above 60 FPS, subjective vection is generally weaker, shorter, and starts later, although this pattern varied slightly according to the speed of stimuli. For objective measures, while the frequency of postural sway was unaffected by frame rate, COP path length was greatest for 480 FPS stimuli. Together, our results support diminishing returns for vection above 60 FPS and provide insight into the use of high frame rate for enhancing the user experience in visual displays.

Stimulus Contrast Information Modulates Sensorimotor Decision Making in Goldfish.

Animal survival relies on environmental information gathered by their sensory systems. We found that contrast information of a looming stimulus biases the type of defensive behavior that goldfish (Carassius auratus) perform. Low-contrast looms only evoke subtle alarm reactions whose probability is independent of contrast. As looming contrast increases, the probability of eliciting a fast escape maneuver, the C-start response, increases dramatically. Contrast information also modulates the decision of when to escape. Although response latency is known to depend on looming retinal size, we found that contrast acts as an additional parameter influencing this decision. When presenting progressively higher contrast stimuli, animals need shorter periods of stimulus processing to initiate the response. Our results comply with the notion that the decision to escape is a flexible process initiated with stimulus detection and followed by assessment of the perceived risk posed by the stimulus. Highly disruptive behaviors as the C-start are only observed when a multifactorial threshold that includes stimulus contrast is surpassed.

Predicting Neural Response Latency of the Human Early Visual Cortex from MRI-Based Tissue Measurements of the Optic Radiation.

Although the non-invasive measurement of visually evoked responses has been extensively studied, the structural basis of variabilities in latency in healthy humans is not well understood. We investigated how tissue properties of optic radiation could predict interindividual variability in the latency of the initial visually evoked component (C1), which may originate from the primary visual cortex (V1). We collected C1 peak latency data using magnetoencephalography (MEG) and checkerboard stimuli, and multiple structural magnetic resonance imaging (MRI) data from 20 healthy subjects. While we varied the contrast and position of the stimuli, the C1 measurement was most reliable when high-contrast stimuli were presented to the lower visual field (LVF). We then attempted to predict interindividual variability in C1 peak latency in this stimulus condition with a multiple regression model using MRI parameters along the optic radiation. We found that this model could predict >20% of variance in C1 latency, when the data were averaged across the hemispheres. The model using the corticospinal tract did not predict variability in C1 latency, suggesting that there is no evidence for generalization to a non-visual tract. In conclusion, our results suggest that the variability in neural latencies in the early visual cortex in healthy subjects can be partly explained by tissue properties along the optic radiation. We discuss the challenges of predicting neural latency using current structural neuroimaging methods and other factors that may explain interindividual variance in neural latency.

Gabor patterns as stimuli in a rodent visual attention task

BackgroundGabor patterns are defined as the product of a sinusoid function and a Gaussian envelope and are commonly used in visual and attentional research due to their ability to selectively stimulate the primary visual cortex. The aim of this study was to investigate whether Gabor patterns can be used as visual stimuli in the rodent continuous performance test (rCPT), a newly developed task to study attentional function and impulsivity. MethodsSixteen male C57BL/6 J mice were trained in the rCPT using Gabor patterns as visual stimuli and their performance was compared to sixteen mice that were trained using traditional high-contrast pattern stimuli. Mice were compared during training, baseline, and a variable stimulus duration probe. ResultsThe Gabor pattern group required more training sessions to reach criteria than the group with high-contrast patterns. At baseline, the Gabor pattern group showed a higher false alarm rate and a lower discriminability index. As task difficulty increased during the variable stimulus duration probe, differences between groups became more pronounced. Specifically, the Gabor pattern group showed decreased hit rate and discriminability index, as well as increased false alarm rate and premature responses compared to the high-contrast pattern group. ConclusionThis feasibility study showed that it is possible to use Gabor patterns as visual stimuli in the rCPT, although it increases task demands. We discuss the differences between Gabor patterns and high-contrast patterns in the context of translatability of animal models in visual and cognitive research and give two examples of applicability.

Heterogeneous Temporal Contrast Adaptation in Drosophila Direction-Selective Circuits.

In visual systems, neurons adapt both to the mean light level and to the range of light levels, or the contrast. Contrast adaptation has been studied extensively, but it remains unclear how it is distributed among neurons in connected circuits, and how early adaptation affects subsequent computations. Here, we investigated temporal contrast adaptation in neurons across Drosophila's visual motion circuitry. Several ON-pathway neurons showed strong adaptation to changes in contrast over time. One of these neurons, Mi1, showed almost complete adaptation on fast timescales, and experiments ruled out several potential mechanisms for its adaptive properties. When contrast adaptation reduced the gain in ON-pathway cells, it was accompanied by decreased motion responses in downstream direction-selective cells. Simulations show that contrast adaptation can substantially improve motion estimates in natural scenes. The benefits are larger for ON-pathway adaptation, which helps explain the heterogeneous distribution of contrast adaptation in these circuits.

Visual sensitivity and bias oscillate phase-locked to saccadic eye movements.

Oscillations in perceptual performance have been observed before and after a voluntary action, like hand, finger, and eye movements. In particular, discrimination accuracy of suprathreshold contrast stimuli oscillates in the delta range (2-3 Hz) phase-locked to saccadic eye movements. Importantly, saccadic suppression is embedded in phase with these long-lasting perceptual oscillations. It is debated whether these rhythmic modulations affect only appearance of high-contrast stimuli or whether absolute detection threshold is also modulated rhythmically. Here we measured location discrimination of a brief Gabor patch presented randomly between 1 s before and after a voluntary saccade and demonstrated that absolute contrast thresholds oscillated at a similar frequency to suprathreshold contrast discrimination. Importantly, saccadic suppression is also embedded in phase with absolute threshold oscillations. Interestingly, response bias was also found to oscillate at the same frequency in both tasks. However, the frequency was in the alpha range for bias, while it was in the delta range for sensitivity. These results demonstrate the presence of perisaccadic delta oscillations in visual sensitivity phase-locked to saccadic onset, and independent from response bias alpha oscillations. Overall, the present findings reinforce the suggestion of a leading role of oscillations in the temporal binding between eye-movement and visual processing timing.

Luminance potentiates human visuocortical responses.

Our visual system is tasked with transforming variations in light within our environment into a coherent percept, typically described using properties such as luminance and contrast. Models of vision often downplay the importance of luminance in shaping cortical responses, instead prioritizing representations that do not covary with overall luminance (i.e., contrast), and yet visuocortical response properties that may reflect luminance encoding remain poorly understood. In this study, we examined whether well-established visuocortical response properties may also reflect luminance encoding, challenging the idea that luminance information itself plays no significant role in supporting visual perception. To do so, we measured functional activity in human visual cortex when presenting stimuli varying in contrast and mean luminance, and found that luminance response functions are strongly contrast dependent between 50 and 250 cd/m2, confirmed with a subsequent experiment. High-contrast stimuli produced linearly increasing responses as luminance increased logarithmically for all early visual areas, whereas low-contrast stimuli produced either flat (V1) or assorted positive linear (V2 and V3) response profiles. These results reveal that the mean luminance information of a visual signal persists within visuocortical representations, potentially reflecting an inherent imbalance of excitatory and inhibitory components that can be either contrast dependent (V1 and V2) or contrast invariant (V3). The role of luminance should be considered when the aim is to drive potent visually evoked responses and when activity is compared across studies. More broadly, overall luminance should be weighed heavily as a core feature of the visual system and should play a significant role in cortical models of vision.NEW & NOTEWORTHY This neuroimaging study investigates the influence of overall luminance on population activity in human visual cortex. We discovered that the response to a particular stimulus contrast level is reliant, in part, on the mean luminance of a signal, revealing that the mean luminance information of our environment is represented within the visual cortex. The results challenge a long-standing misconception about the role of luminance information in the processing of visual information at the cortical level.

Solvent vapour induced rare single-crystal-to-single-crystal transformation of stimuli-responsive fluorophore: Solid state fluorescence tuning, switching and role of molecular conformation and substituents

Supramolecular interactions and molecular conformations play significant role on producing fluorescent polymorphs with tunable emission in the solid state from single fluorophore. External stimuli-induced structural transformation from one polymorph to another polymorph without losing single crystalline character (single-crystal-to-single-crystal transition (SC-SC)) provides perfect model to understand the structure-property of molecules in the solid state and designing new functional fluorescent materials. Herein we have tailored the substituent groups in the aggregation-induced-emissive (AIE) tetraphenylethylene (TPE) based donor (D)-acceptor (A) fluorophores (TPPA-1-6) and explored fluorescent polymorphs formation and SC-SC transition in the solid state. TPPA-1 showed conformational fluorescent polymorphs via twisted and co-planar conformation between TPE phenyl group and cyanophenyl acceptor phenyl ring. However, single crystal analysis of other derivatives revealed that substituent groups and supramolecular interactions control the molecular conformation and SC-SC transition. Fluorophore with same substituent but positional change also show drastic effect on the fluorescent polymorphs formation and SC-SC transition. Substituents that can form strong intermolecular interactions stabilize the less stable co-planar structure whereas bulky substituents with weak intermolecular interactions produced twisted or both conformers. Photophysical, powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and thermogravimteric (TG) analysis were performed to substantiate and get insight on the structural transformation. The formation of fluorescent polymorphs and SC-SC transition exhibited tunable and switchable solid state fluorescence. The non-planar TPE core has been made use to demonstrate high contrast stimuli induced reversible fluorescence switching. Overall, the present studies attempted to gain information on the structural design for developing SC-SC transforming functional organic fluorescent materials that could be of potential interests for optoelectronic and display devices.

Evaluation of visual evoked potential binocular summation after corneal refractive surgery.

To explore whether visual evoked binocular summation is affected in eyes with refractive errors after refractive surgery. Twenty participants (6M, 14F) aged 20-35years (mean 26.7 ± 4.4) were assessed through pattern-reversal visual evoked potential viewing with their every eye (first right eye and then left eye) and then with both eyes while wearing their best correction before undergoing surgery. Also, parameters of the P100 component of pattern-reversal visual evoked potential were evaluated after 3months of refractive surgery in two different check sizes. Monocular and binocular amplitudes and latencies of P100 wave and binocular summation index were compared between before and after surgery. Monocular visual evoked potentials elicited by two different high-contrast checkerboard-patterned stimuli were significantly reduced in P100 wave amplitude (P < 0.05) after refractive surgery. However, there was no difference between the pre- and post-refractive surgery in the mean value of monocular P100 latency (P > 0.05). Similar to monocular findings of P100 wave amplitude, on binocular viewing, the mean value of pattern-reversal visual evoked potential amplitude was significantly reduced (P < 0.05), and P100 wave latency was prolonged (P < 0.05) after refractive surgery in participants. Also, the mean postoperative binocular summation index value as compared to that in the preoperative was significantly lesser (P < 0.05) for the subject in this study. Refractive surgery can degrade binocular visual performance throughout the change in visual evoked potential binocular summation. However, monocular function deteriorates less than binocular function after refractive surgery.

A Sparse Probabilistic Code Underlies the Limits of Behavioral Discrimination.

The cortical code that underlies perception must enable subjects to perceive the world at time scales relevant for behavior. We find that mice can integrate visual stimuli very quickly (<100 ms) to reach plateau performance in an orientation discrimination task. To define features of cortical activity that underlie performance at these time scales, we measured single-unit responses in the mouse visual cortex at time scales relevant to this task. In contrast to high-contrast stimuli of longer duration, which elicit reliable activity in individual neurons, stimuli at the threshold of perception elicit extremely sparse and unreliable responses in the primary visual cortex such that the activity of individual neurons does not reliably report orientation. Integrating information across neurons, however, quickly improves performance. Using a linear decoding model, we estimate that integrating information over 50–100 neurons is sufficient to account for behavioral performance. Thus, at the limits of visual perception, the visual system integrates information encoded in the probabilistic firing of unreliable single units to generate reliable behavior.

Action priming is linked to visual perception in continuous flash suppression.

Visual prime stimuli can affect the processing of following target stimuli even if their visibility is reduced due to visual masking. Prime visibility depends on the stimulus parameters of the prime and those of the mask. Here we explored the effects of prime stimuli and modulated their visibility by continuous flash suppression (CFS). CFS reduces the visibility of a stimulus presented to one eye by simultaneously presenting a series of high-contrast masking stimuli to the other eye. We manipulated the strength of CFS effects on perception and examined how action priming effects of the masked stimuli varied under the same conditions. Prime visibility was modulated by the contrast of the primes (Experiments 1 and 2), the contrast of the masks (Experiments 2 and 3), and by the stimulus onset asynchrony between prime and target stimuli (all experiments). Surprisingly, action priming effects were modulated by these experimental variables in a parallel way. In addition, individual differences between participants in prime visibility correlated with individual differences in action priming. Our findings suggest that action priming and prime perception depend in similar ways on prime contrast, mask contrast, stimulus onset asynchrony, and individual dispositions in CFS. These findings distinguish CFS from other perceptual suppression techniques, such as backward masking, that allow reducing prime visibility without parallel effects on action priming. Our results corroborate the view that CFS interferes with visual processing at early stages in the cortical hierarchy with similar effects on later processing for perception and action.

Failures in top-down control in schizophrenia revealed by patterns of saccadic eye movements.

Successful execution of many behavioral goals relies on well-organized patterns of saccadic eye movements, and in complex tasks, these patterns can reveal the component processes underlying task performance. The present study examined the pattern of eye movements in a visual search task to provide evidence of attentional control impairments in people with schizophrenia (PSZ). We tested PSZ(N = 38) and nonpsychiatric control subjects (NCS, N = 35) in a task that was designed to stress top-down control by pitting task goals against bottom-up salience. Participants searched for either a low-contrast (nonsalient) or a high-contrast (salient) target among low- and high-contrast distractors. By examining fixations of the low- and high-contrast items, we evaluated the ability of PSZ and NCS to focus on low-salience targets and filter out high-salience distractors (or vice versa). When participants searched for a salient target, both groups successfully focused on relevant, high-contrast stimuli and filtered out target-mismatched, low-contrast stimuli. However, when searching for a nonsalient target, PSZ were impaired at efficiently suppressing high-contrast (salient) distractors. Specifically, PSZ were more likely than NCS to fixate and revisit salient distractors, and they dwelled on these items longer than did NCS. The results provide direct evidence that PSZ are impaired in their ability to utilize top-down goals to overcome the prepotent tendency to focus attention on irrelevant but highly salient information. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Gaze stabilization in mantis shrimp in response to angled stimuli

Gaze stabilization is a fundamental aspect of vision and almost all animals shift their eyes to compensate for any self-movement relative to the external environment. When it comes to mantis shrimp, however, the situation becomes complicated due to the complexity of their visual system and their range of eye movements. The stalked eyes of mantis shrimp can independently move left and right, and up and down, whilst simultaneously rotating about the axis of the eye stalks. Despite the large range of rotational freedom, mantis shrimp nevertheless show a stereotypical gaze stabilization response to horizontal motion of a wide-field, high-contrast stimulus. This response is often accompanied by pitch (up-down) and torsion (about the eye stalk) rotations which, surprisingly, have no effect on the performance of yaw (side-to-side) gaze stabilization. This unusual feature of mantis shrimp vision suggests that their neural circuitry for detecting motion is radially symmetric and immune to the confounding effects of torsional self-motion. In this work, we reinforce this finding, demonstrating that the yaw gaze stabilization response of the mantis shrimp is robust to the ambiguous motion cues arising from the motion of striped visual gratings in which the angle of a grating is offset from its direction of travel.