Once a target object is identified, smooth pursuit eye movements are used to track the object as we, or the object, move through the environment. Smooth pursuit eye movements are slow eye movements that follow a target and are used to maintain its position on the fovea. The smooth pursuit eye movements studied here are conjugate with the eyes moving together and the angle between them preserved. A visual stimulus is usually required to initiate a smooth pursuit eye movement (Rashbass, 1961). Although, by degrading the available retinal information, to the extent that perceived motion was either inaccurate or illusory, Steinbach (1976) reported that smooth pursuit only requires an ‘appreciation of the object in motion with respect to the observer, regardless of retinal stimulation’. Smooth pursuit can be elicited by non-visual information, with proprioceptive and tactile information proving effective for both the initiation and maintenance of pursuit (Berryhill, Chiu, & Hughes, 2006).
Smooth pursuit eye movements are most accurate up to around 30deg/s, but fail to accurately keep up with faster stimuli (Robinson, 1965). Predictable wave forms have proved to be excellent targets for inducing accurate smooth pursuit (Stark, Vossius & Young, 1962; Dallos & Jones, 1963; Yasui & Young, 1984), and were employed in the studies reported here. Whilst the initiation of pursuit usually has a time delay of around 150ms this can be avoided using a predictable wave form (McHugh & Bahill, 1985). The direction of smooth pursuit also plays a role, with the best gains being achieved during horizontal pursuit in humans (Rottach et al., 1996).
1.2.2 Saccades
Saccades are ballistic eye movements that rapidly move the eye to a point o...
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...(von Holst and Mittelstaedt, 1950). von Holst and Mittelstaedt suggested that the signal sent to control the extra-ocular muscles is additionally copied to the perceptual centre of the brain. Von Holst and Mittelstaedt provided evidence for an extra-retinal efferent copy by inverting the head of a fly (von Holst and Mittelstaedt, 1950, in Rosenbaum, D.A., 2009). This reversed the relationship between visual motion and the internal estimate of physical motion during flight. Flying to the right provided inaccurate feedback that the fly was moving to the left. In trying to compensate for the incorrect feedback and regain it’s heading, the fly travelled in circles, in a positive feedback loop. The fly moved normally in darkness. The motion perception mechanisms of the fly had been distorted in ways which could not be predicted by changes to retinal motion alone.
My scientific concept is how sight effects balance. Balance is the equal distribution of weight. “Balance is controlled by the vestibular system, which includes the eyes, the inner ear, and other sensory systems of the body” (asha.org). The visual system interacts with the vestibular system by using the
Barlow (1953) first postulated the existence of feature-sensitive ganglion cells in a frog’s retina based on an inhibitory-surround structure of the receptive field. He maintained that the “on-off” units of these cells triggered by the presence of a particular stimulus corresponded to certain behaviour in the frog. For example, presenting a spot of light in the visual field would cause certain neurons to fire in a particular ganglion cell, and in a live frog, would cause the frog to snap at the stimulus. Barlow concluded that these cells must be “fly detectors”. Lettvin et al. (1959) further examined the visual mechanisms of the frog and discerned fo...
Vision plays a huge role in the lives of non-human primates. Non-human primates have exceptional binocular vision, due to forward-facing eyes with overlapping visual fields (Prescott). This binocular stereoscopic color vision allows primates to see the world in terms of height, width, and depth, also known as three-dimensional vision (Haviland et al. 2010). Highly developed vision allows the later arboreal primates to judge depth, distance, and location when moving at speed from branch to branch (Haviland et al. 2010). This bino...
Classical theories demonstrating the inattentional blindness paradigm are (1) the perceptual load, (2) inattentional amnesia and (3) expectation.
The researchers’ hypothesis is premised on a theory first proposed by Charles Darwin called the “facial feedback hypothesis” (Finzi et. al., 2014). Darwin suggested that the feedback our brains receive from the contraction of our facial muscles plays a casual role in cont...
Shapiro, F. (2001). Eye Movement Desensitization and Reprocessing: Basic Principles, Protocols, and Procedures (2nd ed.). New York, New York: Guilford Press.
As with the mental map experiments, the fact that reaction time depends directly on the degree of rotation has been taken as evidence that we solve the...
In addition to sight, signals coming from muscles and joints, called proprioceptors, are sensitive to changes in position. The third contributor to the human tower and the topic of discussion in this paper is the vestibular system. A three-person human tower in the dark must not have enough information coming from the vestibular and proprioceptive systems to function without vision, whereas the two-person tower did have enough information. The ear houses some of the most sensitive organs in the body. The physics of sound is well understood, while the mechanics of how the inner ear translates sound waves into neurotransmitters that then communicate to the brain is still incomplete.
Blindsight is often understood as supporting certain claims concerning the function and the status of the phenomenal qualities of visual perceptions. In this talk I am going to present a short argument to show that blindsight could not be understood as evidence for these claims. The reason is that blindsight cannot be adequately described as a special case of seeing. Consequently, it is not possible to draw inferences from it concerning the role of the phenomenal qualities for seeing.
Muller, N. G., Bartelt, O. A., Donner, T. H., Villringer, A. & Brandt, S. A. (2003). A physiological correlate of the “zoom lens” of visual attention. The Journal of Neuroscience, 23(9): 3561-3565.
In A New Theory of Vision, Berkeley attempts to show that all experience is reducible to sense data by exploiting two types of argument. At times he exploits a scientific account of perception and of the functioning of the perceptual organs, while at other times he uses the argument from illusions.
Donovan, W. L. & Leavitt, L. A. (1980). Physiologic correlates of direct and averted gaze. Biological Psychology, 10, 189-199.
In the process of human infants’ development, infants start to learn how to communicate with the others at the surprising early age, for example: Newborns can follow objects to make saccades to peripheral targets (Farroni et al., 2004);Infants’ responding eye gaze behaviour increase constantly since two months old (Scaife & Bruner, 1975); Cooper and Aslin pointed out that this preference showed up as early as the infants were one month old in 1990. Infants not only can respond to eye contact, vocal cues also are used for gaining more reference information during a communication, particularly when the speech is conducted forward to the infants. It had been reported in many studies that infants show more preference to infant-directed communication
Your eyes contain the receptors responsible for sight, which is the most dominant sense in humans. These receptors or “sensors” receive information about the surrounding environment and pass this information to your brain through the optic nerve. Your brain rapidly processes this information and creates the images you see, which allows you to see stationary objects, as well as follow moving objects whether your head is moving or is stationary.