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This chapter reviews the features of the visual and oculomotor systems that are particularly important for understanding active vision. First, the chapter describes the inhomogeneity of the visual projections and the consequences of the resulting inhomogeneity on visual abilities. Human vision has a high resolution fovea at the centre and visual ability falling off quickly into peripheral vision. Second, the evidence for multiple types of parallel processing within the visual and oculomotor system is reviewed. Third, the basic characteristics of the oculomotor system are described and different types of eye movement are identified, followed by a more detailed description of saccadic eye movements: the fast ballistic eye movements that move the fovea to point at regions of interest.

Instruction mediated through sign language interpretation has become more and more common in higher education with the growing presence deaf and hard-of-hearing (DHH) students. At the same time, it is increasingly common for instructors to augment traditional lectures with visual displays, encouraged by research demonstrating that memory and learning are enhanced by engaging multiple modalities While hearing students can take advantage of multiple, concurrent streams of information in the modern classroom, DHH students need to shift their attention rapidly between the instructor, the sign language interpreter, and the visual display. This chapter discusses two experiments that monitored the gaze of DHH and hearing students in a classroom environment that included instruction mediated through sign language. The results highlight the need for educators to consider the additional demands on DHH students in modern classrooms, especially those mediated by sign-language interpreters. Because they cannot take advantage of the same concurrent streams of information as their hearing counterparts, they must shift serially between multiple sources of information.

This chapter reviews the development of visual functions, with an emphasis on the development of depth perception. The discussions cover the development of basic functions; the growth of the oculomotor system; the development of depth perception; the development of stereoacuity; and binocular correspondence.

Peter H. Schiller, in collaboration with numerous investigators, has carried out research using psychophysical methods, single-cell recordings, microstimulation and pharmacological manipulations. The research has examined (1) The neural underpinnings of visual illusions and visual masking, (2) Retrograde amnesia, (3) The neural control of eye movements, (4) The functions of the midget and parasol systems that originate in the retina, (5) the functions of the ON and OFF channels of the retina and (6) The functions of extrastriate areas in visual processing. Studies at the present time are engaged in assessing the feasibility of creating a prosthetic device for the blind based on electrical stimulation of area V1 and in specifying the neural mechanisms that underlie depth processing.

This chapter examines the role of neural activity in the lateral intraparietal area (LIP) on intention to make saccadic eye movement and on attention in the lateral intraparietal area in monkeys. It describes the results of experiments which reveal that LIP predicts a monkey's attention on a millisecond-by-millisecond basis and is independent from saccade planning. It shows that the activity of LIP predicts the goal and latency of saccades in a free-viewing visual search task and suggests that it provides a salience map which is interpreted by the oculomotor system as a saccade goal when a saccade is appropriate.

Considering the neural visuomotor processes obtained by behaviorally relevant sign stimuli, it was realized that investigations in mammals are very intricate. In mammals, the retina is functionally divided into an event-signaling periphery and a central fovea. The oculomotor system is adapted to this property. If an object appears in the peripheral visual field, eye movements direct the fovea to the locus of interest. These ballistic eye movements are relatively fast and not object-specific but event-related. Once the fovea is on target, feedback-guided fixation and smooth-pursuit eye movements provide the conditions for feature analysis and recognition, which are criteria to select the necessary goal-directed behavior.