Amount Of Head Movement Research Articles

Disentangling Morphological and Environmental Drivers of Foraging Activity in an Invasive Diurnal Gecko, Phelsuma laticauda

In recent years, substantial variation in foraging behavior has been documented in lizards, including within and between closely related species. However, the exceptionally variable Gekkota still suffers from low sampling effort and historical averaging of foraging mode values across taxonomic levels. Herein, we address the gap in foraging modes of geckos by parsing out environmental and morphological sources of variation in foraging mode within the diurnal arboreal gecko, Phelsuma laticauda. Foraging behavior was examined at two sites on the island of Mo'orea, French Polynesia. In fall 2018, we made observations for a maximum duration of 30 min on 31 individual geckos. We found that P. laticauda exhibits a sit-and-wait strategy and that its foraging behavior is influenced by several ecological and morphological correlates: sex, body size, temperature, and date of observation. Notably, we found a trend for more active foraging by females than by males, challenging the notion that only nocturnal geckos exhibit sexual foraging diergism. The amount of time spent pausing and the maximum single movement exhibited a negative relationship with the body size of an individual. At higher temperatures, the amount of head movements, likely pertaining to locating prey, increased. Several foraging metrics varied with date of observation. Our results emphasize the need to consider multiple ecological correlates when studying foraging behavior as well as the importance of measuring multiple behavioral metrics beyond the standard percent time moving and moves per minute.

Eye Movement Control in the Argus II Retinal-Prosthesis Enables Reduced Head Movement and Better Localization Precision.

Visual scanning by sighted individuals is done using eye and head movements. In contrast, scanning using the Argus II is solely done by head movement, since eye movements can introduce localization errors. Here, we tested if a scanning mode utilizing eye movements increases visual stability and reduces head movements in Argus II users. Eye positions were measured in real-time and were used to shift the region of interest (ROI) that is sent to the implant within the wide field of view (FOV) of the scene camera. Participants were able to use combined eye-head scanning: shifting the camera by moving their head and shifting the ROI within the FOV by eye movement. Eight blind individuals implanted with the Argus II retinal prosthesis participated in the study. A white target appeared on a touchscreen monitor and the participants were instructed to report the location of the target by touching the monitor. We compared the spread of the responses, the time to complete the task, and the amount of head movements between combined eye-head and head-only scanning. All participants benefited from the combined eye-head scanning mode. Better precision (i.e., narrower spread of the perceived location) was observed in six out of eight participants. Seven of eight participants were able to adopt a scanning strategy that enabled them to perform the task with significantly less head movement. Integrating an eye tracker into the Argus II is feasible, reduces head movements in a seated localization task, and improves pointing precision.

Gaze Contingent Control for a Robotic Laparoscope Holder

Gaze Contingent Control for a Robotic Laparoscope Holder

Drift and ownership toward a distant virtual body

In body ownership illusions participants feel that a mannequin or virtual body (VB) is their own. Earlier results suggest that body ownership over a body seen from behind in extra personal space is possible when the surrogate body is visually stroked and tapped on its back, while spatially and temporal synchronous tactile stimulation is applied to the participant's back. This result has been disputed with the claim that the results can be explained by self-recognition rather than somatic body ownership. We carried out an experiment with 30 participants in a between-groups design. They all saw the back of a VB 1.2 m in front, that moved in real-time determined by upper body motion capture. All felt tactile stimulation on their back, and for 15 of them this was spatially and temporally synchronous with stimulation that they saw on the back of the VB, but asynchronous for the other 15. After 3 min a revolving fan above the VB descended and stopped at the position of the VB neck. A questionnaire assessed referral of touch to the VB, body ownership, the illusion of drifting forwards toward the VB, and the VB drifting backwards. Heart rate deceleration (HRD) and the amount of head movement during the threat period were used to assess the response to the threat from the fan. Results showed that although referral of touch was significantly greater in the synchronous condition than the asynchronous, there were no other differences between the conditions. However, a further multivariate analysis revealed that in the visuotactile synchronous condition HRD and head movement increased with the illusion of forward drift and decreased with backwards drift. Body ownership contributed positively to these drift sensations. Our conclusion is that the setup results in a contradiction—somatic feelings associated with a distant body—that the brain attempts to resolve by generating drift illusions that would make the two bodies coincide.

Investigation into and modelling of head movement for objective evaluation of the spatial impression of audio.

Research was undertaken to determine the nature of head movements made when judging spatial impression and to incorporate these into a system for measuring, in a perceptually relevant manner, the acoustic parameters which contribute to spatial impression: interaural time and level differences and interaural cross-correlation coefficient. First, a subjective test was conducted that showed that (i) the amount of head movement was larger when evaluating source width and envelopment than when judging localization and timbre and (ii) the pattern of head movement resulted in ear positions that formed a sloped area. These findings led to the design of a binaural signal capture technique using a sphere with multiple microphones, mounted on a simulated torso. Evaluation of this technique revealed that it would be appropriate for the prediction of perceived spatial attributes including both source direction and aspects of spatial impression. Reliable derivation of these attributes across the range of ear positions determined from the earlier subjective test was shown to be possible with a limited number of microphones through an appropriate interpolation and calculation technique. A prototype capture system was suggested as a result, using a sphere with torso, with 21 omnidirectional microphones on each side. [Work supported by the Engineering and Physical Sciences Research Council (EPSRC), UK, Grant No. EP/D049253.]

A quantitative analysis of head movement behaviour during visual acuity assessment under prosthetic vision simulation

In most current vision prosthesis designs, head movement is the sole director of visual gaze and scanning due to the head-mounted nature of the camera. Study of this unnatural behaviour may provide insight into improved prosthesis designs and rehabilitation procedures. In this paper, we conducted a psychophysical study to investigate the characteristics of head movements of normally sighted subjects undergoing a visual acuity task in simulated prosthetic vision (SPV). In 12 naïve, untrained subjects, we recorded spontaneous changes in the amount of head movements during SPV sessions compared to control (normal vision) sessions. The observed behaviour continued to be refined until five or six sessions of practice. Increased head movement velocity was shown to be correlated to improved visual acuity performance, up to 0.3 logMAR, an equivalent of detecting details at half the physical size compared to complete deprivation of head movements. We postulate that visual scanning can as much as double the spatial frequency information in prosthetic vision. Increased head movement velocity observed when subjects were attempting smaller test items and for low-pass filtering schemes with higher cut-off frequencies may be further evidence that higher frequency content may be available through visual scanning, unconsciously driving subjects to increase head movement velocity.

Postural modifications of VDU operators wearing bifocal spectacles

This paper describes the postural changes experienced by presbyopic operators of VDU workstations while wearing a pair of bifocal spectacles. All operators reported in this paper had suffered neck and back aches, in addition to generalised problems of asthenopia, while using the VDU workstation. The ages of the operators ranged between 47 and 58 years. The operators' head movements, in looking from the keyboard to the screen, were two to three times greater when bifocal spectacles were worn compared with specially prescribed single-vision occupational spectacles. There were also greater movements in the flexion of the wrist and elbow while using bifocal spectacles and looking from the keyboard to the screen. There was no relationship between the amount of head movement and the position of the bifocal reading segment with respect to the operators' pupil. It was concluded that the symptoms reported by these presbyopic operators were due to static loading of the muscles in the neck and back, induced by the use of bifocal spectacles.

BEHAVIORAL AND PHYSIOLOGICAL RESPONSES TO SPATIAL NOVELTY IN DAIRY COWS

Thirty-two lactating Holstein cows were used in a study of excitability and agonistic behavior of dairy cattle. When cattle were moved from a familiar stall to an unfamiliar place, heart rate immediately increased on average from 83.2 to 107.8 (P < 0.01). The total distance of head movement in a novel environment varied considerably. The animal with the greatest head movement had a distance 6.6 times larger than the cow with the least head movement. Significant deviation from the mean values of agonistic interactions were found for 28 cows: of these 10 showed tendencies for physical attacks (P < 0.05), 5 for threats (P < 0.05), 6 for displacement of physical attacks (P < 0.05), and 7 showed significant tendencies for avoidance when threatened (P < 0.05). Both the instigator and victim cows that showed a higher proportion of the psychological form of agonistic behavior also tended to show a larger amount of head movement with less variation, lower increase in heart rate, and less change in norepinephrine concentration due to transfer. The results indicate that analyses of head movement patterns may be used for an assessment of excitability of cows. Key words: Cow, behavior, spatial novelty, head movement, excitability, temperament

Binary Search Revisited: Another Advantage of Fibonacci Search

Binary search method is a well-known and a fundamental technique to search a key out of an ordered table. Fibonacci serh is kind of binary search adopting nonequal splitting criterion for dividing the remaining part of the table. This paper clarifies another advantage of Fibonacci search, which has not been found so far. First, it is shown that, from the viewpoint of the amount of head movement, Fibonacci search gives more than 10 percent better efficiency than the ordinary binary search. Furthermore, we propose a novel variation of Fibonacci search, and show that it attains nearly 20 percent better efficiency in average than the ordinary binary search.