Non-visual Cues Research Articles

Insights into the Social Behavior of Surface and Cave-Dwelling Fish (Poecilia mexicana) in Light and Darkness through the Use of a Biomimetic Robot

Biomimetic robots (BRs) are becoming more common in behavioral research and, if they are accepted as conspecifics, allow for new forms of experimental manipulations of social interactions. Nevertheless, it is often not clear which cues emanating from a BR are actually used as communicative signals and how species or populations with different sensory makeups react to specific types of BRs. We herein present results from experiments using two populations of livebearing fishes that differ in their sensory capabilities. In the South of Mexico, surface-dwelling mollies (Poecilia mexicana) successfully invaded caves and adapted to dark conditions. While almost without pigment, these cave mollies possess smaller but still functional eyes. Although previous studies found cave mollies to show reduced shoaling preferences with conspecifics in light compared to surface mollies, it is assumed that they possess specialized adaptations to maintain some kind of sociality also in their dark habitats. By testing surface- and cave-dwelling mollies with RoboFish, a BR made for use in laboratory experiments with guppies and sticklebacks, we asked to what extent visual and non-visual cues play a role in their social behavior. Both cave- and surface-dwelling mollies followed the BR as well as a live companion when tested in light. However, when tested in darkness, only surface-dwelling fish were attracted by a live conspecific, whereas cave-dwelling fish were not. Neither cave- nor surface-dwelling mollies were attracted to RoboFish in darkness. This is the first study to use BRs for the investigation of social behavior in mollies and to compare responses to BRs both in light and darkness. As our RoboFish is accepted as conspecific by both used populations of the Atlantic molly only under light conditions but not in darkness, we argue that our replica is providing mostly visual cues.

Online interviewing with interpreters in humanitarian contexts

ABSTRACT Purpose: Recognising that one way to address the logistical and safety considerations of research conducted in humanitarian emergencies is to use internet communication technologies to facilitate interviews online, this article explores some practical and methodological considerations inherent to qualitative online interviewing. Method: Reflections from a case study of a multi-site research project conducted in post-conflict countries are presented. Synchronous online cross-language qualitative interviews were conducted in one country. Although only a small proportion of interviews were conducted online (six out of 35), it remains important to critically consider the impact upon data produced in this way. Results: A range of practical and methodological considerations are discussed, illustrated with examples. Results suggest that whilst online interviewing has methodological and ethical potential and versatility, there are inherent practical challenges in settings with poor internet and electricity infrastructure. Notable methodological limitations include barriers to building rapport due to partial visual and non-visual cues, and difficulties interpreting pauses or silences. Conclusions: Drawing upon experiences in this case study, strategies for managing the practical and methodological limitations of online interviewing are suggested, alongside recommendations for supporting future research practice. These are intended to act as a springboard for further reflection, and operate alongside other conceptual frameworks for online interviewing.

Non-optimal perceptual decision in human navigation

We highlight that optimal cue combination does not represent a general principle of cue interaction during navigation, extending Rahnev & Denison's (R&D) summary of nonoptimal perceptual decisions to the navigation domain. However, we argue that the term "suboptimality" does not capture the way visual and nonvisual cues interact in navigational decisions.

Females of the annual killifish Austrolebias reicherti (Cyprinodontiformes: Rivulidae) recognize conspecific mates based upon chemical cues

Olfactory abilities to discriminate conspecifics can be determinant to prevent hybridization between closely-related species in many taxa. Annual killifish Austrolebias reicherti and A. charrua are sister species inhabiting temporary ponds within Eastern Wetlands of Uruguay with an overlapping area in their distributions. Herein, we assess species recognition sensory abilities in females of A. reicherti in classic dual-choice tests. We exposed two different groups of females, one to olfactory but not visual cues, and the other to visual but not olfactory cues, from conspecific and heterospecific A. charrua males. Austrolebias reicherti females preferred conspecific males when based solely on olfactory cues, and showed no discrimination when exposed to visual traits only. Austrolebias inhabit shallow, muddy and highly turbid ponds that may promote the use of non-visual cues. Although preliminary, the results of this study suggest the importance of chemical communication in species mate recognition in A. reicherti and points annual fishes as a promising model to study the role of mate choice in reproductive isolation and speciation.

Multisensory control of a straight locomotor trajectory.

Locomotor steering is contingent upon orienting oneself spatially in the environment. When the head is turned while walking, the optic flow projected onto the retina is a complex pattern comprising of a translational and a rotational component. We have created a unique paradigm to simulate different optic flows in a virtual environment. We hypothesized that non-visual (vestibular and somatosensory) cues are required for proper control of a straight trajectory while walking. This research study included 9 healthy young subjects walking in a large physical space (40×25m2) while the virtual environment is viewed in a helmet-mounted display. They were instructed to walk straight in the physical world while being exposed to three conditions: (1) self-initiated active head turns (AHT: 40° right, left, or none); (2) visually simulated head turns (SHT); and (3) visually simulated head turns with no target element (SHT_NT). Conditions 1 and 2 involved an eye-level target which subjects were instructed to fixate, whereas condition 3 was similar to condition 2 but with no target. Identical retinal flow patterns were present in the AHT and SHT conditions whereas non-visual cues differed in that a head rotation was sensed only in AHT but not in SHT. Body motions were captured by a 12-camera Vicon system. Horizontal orientations of the head and body segments, as well as the trajectory of the body's centre of mass were analyzed. SHT and SNT_NT yielded similar results. Heading and body segment orientations changed in the direction opposite to the head turns in SHT conditions. Heading remained unchanged across head turn directions in AHT. Results suggest that non-visual information is used in the control of heading while being exposed to changing rotational optic flows. The small magnitude of the changes in SHT conditions suggests that the CNS can re-weight relevant sources of information to minimize heading errors in the presence of sensory conflicts.

Does blindness influence trust? A comparative study on social trust among blind and sighted adults

Although blind individuals must often rely on others to navigate their physical environment, recent studies concerning differences between blind and sighted persons in attributing social traits to others based on nonvisual cues remain inconclusive. Here we examined whether blind and sighted individuals vary in their level of social trust in others. One hundred and twenty-four healthy men and women participated in the study, including 32 congenitally blind, 27 late blind, and 65 sighted adult controls. We measured levels of social trust represented by two independent convictions, that people are exploitative, or dishonest. Linear mixed models showed no significant differences between sighted, late blind and congenitally blind individuals, indicating that visual deprivation does not predict level of trust in others. For both blind and sighted participants, the belief that people are exploitative was stronger than the belief that people are dishonest.

Visual and cross-modal cues increase the identification of overlapping visual stimuli in Balint’s syndrome

ABSTRACTIntroduction: Cross-modal interactions improve the processing of external stimuli, particularly when an isolated sensory modality is impaired. When information from different modalities is integrated, object recognition is facilitated probably as a result of bottom-up and top-down processes. The aim of this study was to investigate the potential effects of cross-modal stimulation in a case of simultanagnosia. Method: We report a detailed analysis of clinical symptoms and an 18F-fluorodeoxyglucose (FDG) brain positron emission tomography/computed tomography (PET/CT) study of a patient affected by Balint’s syndrome, a rare and invasive visual–spatial disorder following bilateral parieto-occipital lesions. An experiment was conducted to investigate the effects of visual and nonvisual cues on performance in tasks involving the recognition of overlapping pictures. Four modalities of sensory cues were used: visual, tactile, olfactory, and auditory. Results: Data from neuropsychological tests showed the presence of ocular apraxia, optic ataxia, and simultanagnosia. The results of the experiment indicate a positive effect of the cues on the recognition of overlapping pictures, not only in the identification of the congruent valid-cued stimulus (target) but also in the identification of the other, noncued stimuli. All the sensory modalities analyzed (except the auditory stimulus) were efficacious in terms of increasing visual recognition. Conclusions: Cross-modal integration improved the patient’s ability to recognize overlapping figures. However, while in the visual unimodal modality both bottom-up (priming, familiarity effect, disengagement of attention) and top-down processes (mental representation and short-term memory, the endogenous orientation of attention) are involved, in the cross-modal integration it is semantic representations that mainly activate visual recognition processes. These results are potentially useful for the design of rehabilitation training for attentional and visual–perceptual deficits.

Role of visual and non-visual cues in damselfly mate recognition

In many species of damselflies, sexual conflict in the form of male harassment is thought to explain the widespread existence of female-limited color polymorphisms. With a few exceptions, the majority of investigations into these mating systems have assumed that male damselflies primarily use visual cues to detect and recognize their mates. Recently, laboratory studies have demonstrated that damselflies orient to olfactory signals from prey and that males orient to chemical cues from conspecific females. However, to date there are no field experiments which explicitly test the role that chemical cues play in sex recognition. Here we used a field experiment on Enallagma civile damselflies to test if free flying males detect and recognize females in the absence of visual cues through the use of non-visual signals. In the absence of visual cues males did not exhibit positive responses toward female conspecifics, whereas when both visual and non-visual cues were present, males readily detected females and oft...

Head roll stabilisation in the nocturnal bull ant Myrmecia pyriformis: implications for visual navigation.

Ant foragers are known to memorise visual scenes that allow them to repeatedly travel along idiosyncratic routes and to return to specific places. Guidance is provided by a comparison between visual memories and current views, which critically depends on how well the attitude of the visual system is controlled. Here we show that nocturnal bull ants stabilise their head to varying degrees against locomotion-induced body roll movements, and this ability decreases as light levels fall. There are always un-compensated head roll oscillations that match the frequency of the stride cycle. Head roll stabilisation involves both visual and non-visual cues as ants compensate for body roll in complete darkness and also respond with head roll movements when confronted with visual pattern oscillations. We show that imperfect head roll control degrades navigation-relevant visual information and discuss ways in which navigating ants may deal with this problem.

Comment from the Field

A couple of years ago I stopped using the words blind and visually impaired to describe my experience because I realized that my experience did not center on the visual sense anymore. I had just moved to Portland and was in the process of learning a bunch of important walking routes-like the route from my apartment to the train that would bring me to school, and the route from my apartment to the coffee shop or grocery store. My friend Jason Sturgill had just given me a camera as a way of encouraging me to capture images of the things that might catch my attention on a given day. It was a way for us to get to know each other because we had just started grad school together, and had somewhat identified with one another on the basis that we both had to learn to see differently at a point in our lives: me at age 21, I started to shift toward non-visual ways of knowing the world, and Jason, sometime during his teenage years, he managed, in a split second, to prove the you'll shoot your eye theory is sound, by experimenting with some old tin cans and a BB gun.I would take the camera for the weekend and we would meet up the following week at school so Jason could describe to me what I had shot. Initially my subject matter centered on the moments after a significant peak in the soundscape-like the moment after an abrupt mechanical noise or after someone's voice had risen significantly during a conversation. The only reason that I chose to focus on the moment directly after a sound event, as opposed to focusing on the sound event itself, was because it would take a few seconds for me to pull out the camera and get situated-and by the time the shot was all lined up, the sound in question would already be a memory. I started titling these photos, for myself, after Jillian laughed really loud or when that truck with the backfiring engine passed by. However, I would show the images to Jason, a fair bit of negotiating went on between us in order to distinguish what the heck I had photographed. Jason would say something like, you got a picture of a street, it looks like the corner across from the bookstore and I would say something like, oh yeah, that was taken as I was waiting to cross the street, after a truck with a backfiring engine passed by.Soon this process of taking photos based on some non-visual cue synchronized with the process of me learning my walking routes-and it synchronized with a thud. I was walking beside my apartment, toward the crossing street to the train station and, in the process, walked right into a tree branch that was hanging lower than usual due to a recent downpour. Slightly startled, and with a face full of soggy foliage, I reached for my camera and took a photo of the delinquent tree branch-the low hanging tree branch by my apartment. With Jason's encouragement, it became one in a collection of photos of the things that I had physical interactions with while on walks.There were photos of street signs, metal poles, fire hydrants, sandwich boards, brick walls, trees, bike racks, pylons, wet floor signs, windows, doors, fences, bus shelters and a lone land surveyor's tripod. My process went something like this: I would be walking to grab some breakfast at the cafe near my apartment and I would be fantasizing about my morning coffee. My head would be in the clouds of foam that would surely crown the cappuccino that I would order, and would therefore not be on my immediate surroundings. Then thud, I would smash my knee into a bike rack. The rush of pain was my signal to reach into my bag, feel around for the camera, locate the camera, pull out the camera, take the camera out of its case, situate myself and line up the shot. It worked every time in distracting me from the moment of embarrassment that was so often connected to walking into an obstacle in public.Aside from the visual archive that it produced, this six-month dedication came with the added benefit of learning to navigate the city by simply bumping into it. …

Nonvisual information contributes to flow parsing during walking

To perceive the movement of an independently moving object during self-motion, visual motion caused by object movement must be distinguished from effects of self-motion. This has been termed flow parsing. Flow parsing could be accomplished from optic flow alone. During walking, nonvisual information about self-motion could also potentially contribute. In this study, we measured the relative influence of visual and nonvisual information on perception of object motion and movement control during walking. In a virtual environment, observers walked toward a distant target along a textured ground plane. An independently moving dot appeared briefly during movement, 0.9 m above the ground, and observers judged whether the object was moving leftward or rightward. The horizontal velocity of the object was varied across trials and responses were used to compute a point-of-subjective-equality representing the object motion that is perceived to be stationary. To dissociate visual and nonvisual cues, we presented conditions where the direction of self-motion indicated by optic flow differed from the physical direction of walking by ±5°. In this situation, the relative motion of an object that is stationary with respect to optic flow would not correspond to a stationary object when compared to the physical direction of self-motion, and vice versa. The object motion that is perceived to be stationary can therefore be used to infer the relative influence of visual and nonvisual cues. We also analyzed walking trajectories to estimate the relative influence of visual and nonvisual cues on movement control. We found that nonvisual information strongly influenced both object motion judgments and walking trajectories, with less weighting for object motion (60% vs. 90%). We also found trial-to-trial correlations between biases in walking direction and judgments of object motion. The results suggest that an integrated perception of heading contributes to both movement control and flow parsing. Meeting abstract presented at VSS 2015

Going with, then against the flow: evidence against the optomotor hypothesis of fish rheotaxis

Movement through an environment provides sighted organisms with dynamic visual cues known as optic flow. In flying insects, optic flow is important for collision avoidance, flight speed control and landing manoeuvres. The function of optic flow is much less understood in other taxa, particularly in fish. Despite a lack of quantitative studies, optomotor responses (OMRs) to optic flow are presumed to be nearly ubiquitously important for rheotaxis (orientation to currents), a widespread behaviour that confers a number of benefits, including energy conservation. Here we show that while very young larval zebrafish, Danio rerio, exhibit positive OMRs (swim in the direction of optic flow), thereby minimizing optic flow on the retina, older larvae and adults exhibit negative OMRs that increase optic flow. While the reason for this reversal remains unclear, negative OMRs are inconsistent with optically driven positive rheotaxis (orienting upstream). Furthermore, when optic flow cues are placed in conflict with nonvisual (mechanical) cues generated by water currents, adult fish largely ignore the optic flow cues relying instead on nonvisual cues. These results challenge a century-old belief that optic flow and the resulting OMRs are a dominant sensorimotor mechanism in rheotaxis, highlighting the importance of future work on life history changes in OMRs and the possible modulatory influence of learned, multisensory expectations.

Errors in imaging of traumatic injuries

The advent of multi-detector computed tomography (MDCT) has drastically improved the outcomes of patients with multiple traumatic injuries. However, there are still diagnostic challenges to be considered. A missed or the delay of a diagnosis in trauma patients can sometimes be related to perception or other non-visual cues, while other errors are due to poor technique or poor image quality. In order to avoid any serious complications, it is important for the practicing radiologist to be cognizant of some of the most common types of errors. The objective of this article is to review the various types of errors in the evaluation of patients with multiple trauma injuries or polytrauma with MDCT.

The value of safety and practicality: Recommendations for training disabled students in the sciences with a focus on blind and visually impaired students in chemistry laboratories

We strive to make chemistry more available and exciting for disabled scientists by developing accessible and safe methodologies to be employed by high school, undergraduate, and graduate students. We share philosophies and methods that were found to be effective in ensuring a safe laboratory environment. Namely, an accessible and safe chemistry laboratory requires assistance and extensive contributions from everyone involved. A discussion of technologies that make our computational chemistry laboratory accessible to blind and visually impaired (BVI) researchers follows. These recommendations are derived from our personal experiences with learning and teaching chemistry, with serving on a chemistry accessibility committee and with organizing and running chemistry camps for BVI students. In addition, we have begun work with sighted high school students who perform visual activities under blindfold. These experiences challenge the student under blindfold to learn how to function without all five senses while simultaneously training a sighted peer to safely and accurately assist with non-visual cues.

Role of visual and non-visual cues in constructing a rotation-invariant representation of heading in parietal cortex.

As we navigate through the world, eye and head movements add rotational velocity patterns to the retinal image. When such rotations accompany observer translation, the rotational velocity patterns must be discounted to accurately perceive heading. The conventional view holds that this computation requires efference copies of self-generated eye/head movements. Here we demonstrate that the brain implements an alternative solution in which retinal velocity patterns are themselves used to dissociate translations from rotations. These results reveal a novel role for visual cues in achieving a rotation-invariant representation of heading in the macaque ventral intraparietal area. Specifically, we show that the visual system utilizes both local motion parallax cues and global perspective distortions to estimate heading in the presence of rotations. These findings further suggest that the brain is capable of performing complex computations to infer eye movements and discount their sensory consequences based solely on visual cues.

Otolithic information is required for homing in the mouse.

Navigation and the underlying brain signals are influenced by various allothetic and idiothetic cues, depending on environmental conditions and task demands. Visual landmarks typically control navigation in familiar environments but, in the absence of landmarks, self-movement cues are able to guide navigation relatively accurately. These self-movement cues include signals from the vestibular system, and may originate in the semicircular canals or otolith organs. Here, we tested the otolithic contribution to navigation on a food-hoarding task in darkness and in light. The dark test prevented the use of visual cues and thus favored the use of self-movement information, whereas the light test allowed the use of both visual and non-visual cues. In darkness, tilted mice made shorter-duration stops during the outward journey, and made more circuitous homeward journeys than control mice; heading error, trip duration, and peak error were greater for tilted mice than for controls. In light, tilted mice also showed more circuitous homeward trips, but appeared to correct for errors during the journey; heading error, trip duration, and peak error were similar between groups. These results suggest that signals from the otolith organs are necessary for accurate homing performance in mice, with the greatest contribution in non-visual environments.

Gravity in the Brain as a Reference for Space and Time Perception.

Moving and interacting with the environment require a reference for orientation and a scale for calibration in space and time. There is a wide variety of environmental clues and calibrated frames at different locales, but the reference of gravity is ubiquitous on Earth. The pull of gravity on static objects provides a plummet which, together with the horizontal plane, defines a three-dimensional Cartesian frame for visual images. On the other hand, the gravitational acceleration of falling objects can provide a time-stamp on events, because the motion duration of an object accelerated by gravity over a given path is fixed. Indeed, since ancient times, man has been using plumb bobs for spatial surveying, and water clocks or pendulum clocks for time keeping. Here we review behavioral evidence in favor of the hypothesis that the brain is endowed with mechanisms that exploit the presence of gravity to estimate the spatial orientation and the passage of time. Several visual and non-visual (vestibular, haptic, visceral) cues are merged to estimate the orientation of the visual vertical. However, the relative weight of each cue is not fixed, but depends on the specific task. Next, we show that an internal model of the effects of gravity is combined with multisensory signals to time the interception of falling objects, to time the passage through spatial landmarks during virtual navigation, to assess the duration of a gravitational motion, and to judge the naturalness of periodic motion under gravity.

Simulation of Driving in Low-Visibility Conditions: Does Stereopsis Improve Speed Perception?

Laboratory-based studies of perceived speed show that, under most circumstances, perceived speed is reduced as a function of contrast. However, a recent investigation of perceived vehicular speed while driving around a closed road circuit showed no such effect (Owens, Wood, & Carberry, 2010, Perception, 39: , 1199-1215). We sought to probe the source of this discrepancy, asking whether the presence or absence of stereoscopic motion information might account for the difference in results. In a two-alternative forced-choice psychophysical speed-discrimination task, observers compared the speed of high- and low-contrast driving clips filmed with a 3-D camera and presented either stereoscopically (3-D) or monoscopically (2-D). Although perceived speed was reduced at low contrast, the size of this misperception was equivalent for 2-D and 3-D presentations. However, the inclusion of stereoscopic cues to vehicular speed caused significant improvements in the precision of speed judgments. It is concluded that although stereopsis can provide access to valuable information on perceived speed, contrast-independent speed estimation as demonstrated by Owens et al. (2010) is more likely to reflect the use of the full visual field in a real driving situation (compared with limited field of view simulations), or the additional contributions of nonvisual cues rather than stereopsis.

Nonvisual spatial navigation fMRI lateralizes mesial temporal lobe epilepsy in a patient with congenital blindness

Nonvisual spatial navigation functional magnetic resonance imaging (fMRI) may help clinicians determine memory lateralization in blind individuals with refractory mesial temporal lobe epilepsy (MTLE). We report on an exceptional case of a congenitally blind woman with late-onset left MTLE undergoing presurgical memory fMRI. To activate mesial temporal structures despite the lack of visual memory, the patient was requested to recall familiar routes using nonvisual multisensory and verbal cues. Our findings demonstrate the diagnostic value of a nonvisual fMRI task to lateralize MTLE despite congenital blindness and may therefore contribute to the risk assessment for postsurgical amnesia in rare cases with refractory MTLE and accompanying congenital blindness.

Gaze direction affects visuo-spatial short-term memory

Hemispheric asymmetries were investigated by changing the horizontal position of stimuli that had to be remembered in a visuo-spatial short-term memory task. Observers looked at matrices containing a variable number of filled squares on the left or right side of the screen center. At stimulus offset, participants reproduced the positions of the filled squares in an empty response matrix. Stimulus and response matrices were presented in the same quadrant. We observed that memory performance was better when the matrices were shown on the left side of the screen. We distinguished between recall strategies that relied on visual or non-visual (verbal) cues and found that the effect of gaze position occurred more reliably in participants using visual recall strategies. Overall, the results show that there is a solid enhancement of visuo-spatial short-term memory when observers look to the left. In contrast, vertical position had no influence on performance. We suggest that unilateral gaze to the left activates centers in the right hemisphere contributing to visuo-spatial memory.