Sensation And Perception PDF

SENSATION AND PERCEPTION Dr. Tarek Bahaa El Deen  Sensation and Perception Starting from the time when the human eye receives the image and focuses it on the retina, so we have the ability to determine what we see, which is done through six successive stages, although some of...

SENSATION AND PERCEPTION Dr. Tarek Bahaa El Deen  Sensation and Perception Starting from the time when the human eye receives the image and focuses it on the retina, so we have the ability to determine what we see, which is done through six successive stages, although some of them occur at the same time. Since it is not logical to exclude verification in the nature of the issue of visual perception, the rules governing the creation and understanding of images and visual models (Goldstein, 2014).  Sensation and Perception At the heart of this conflict lies the relationship between images and reality. From the time we receive a picture when we can determine what we are seeing, there are six phases identified, some of which occur at about the same time. These “six stages progress primarily sequentially, from the physical functions of the reflexes of the eye and the nervous system to mental functions of the brain, involving memory and thought processes” (Snowden Robert, Thompson Peter, 2012). (Goldstein, 2014)  1- Reception When the light waves enter and the human eye and refracted through the tight transparent layer portion in the front of the eyeball called the cornea. Then passes through the “hole in the middle of the colored part of the eye called the pupil. And then the eye lens focuses the electromagnetic wave (light) on the retina through a process called accommodation. And the light-sensitive photoreceptors cells called rods and cones at the retina” absorbed the various energy in electromagnetic wave (Dragoi, 2013b; Matthen, 2015).  1- Reception As light rays travel only in straight lines, rays of the light come from the top of the subjects being seen are refracted down at the bottom of the human retina, and the rays of the light come from the lower part of the subjects refracted to the top of the retina. Similarly, rays of the light come from the “left side of the subjects refracted to the right side of the human retina, and vice versa for the rays of the light” come from the right side (Dragoi, 2013b; Matthen, 2015). (Snowden Robert, Thompson Peter, 2012)  2- Transduction Transduction is the stage where it is the process by which the photoreceptors cells (cones and rods) convert the electromagnetic waves (light) into another form (electrochemical energy neural impulses) that can be used by the nervous system. Then, transduction results in perception mean the conversion of the visual sensory raw data into another data form that can be processed by the brain (Carpenter & Huffman, 2008).  2- Transduction Electrochemical waves are a form of energy that have teeny electrical charges that move from one neuron to the next one with the assistance of a chemical matter (neurotransmitter). All the visual sensory data must be transduced at the photoreceptor sites before it can be transmitted to the brain, which can only deal with electrochemical energy. The process of transduction is similar to that which happens in a television receiver when converted signals into an electrical form that can be organized and displayed on a television screen (Goldstein, 2014).  2- Transduction To transmit the visual information through the optic nerve to the brain, the image data must be converted to a form that can be transferred and processed in visual system (Goldstein, 2014). (Dragoi, 2013; Matthen, 2015)  3- Transmission After the image has been converted to electrochemical signals, they are sent by a massive interrelated network of neurons, through the optic nerve, to the primary visual cortex in the brain, where specialized receptor cells called feature detectors, respond to specific features of the visual stimulus. When the electrochemical signals travel through this interrelated network of neurons, they mostly meet and affected by different signals in their journey through the road (Tombran-Tink & Barnstable, 2008).  3- Transmission What is the point of taking a complicated and indirect path, if the goal is only to transfer the electrochemical signal from the eye to the brain? Unless the cause exceeds just the transfer of the electrochemical signal, and beyond it to neural processing, in which the interaction between different signals in different neurons, to produce a new electrochemical representation for the stimulus original electrochemical representation (Goldstein, 2014). (Goldstein, 2014)  4- Selection In this step, the visual system faces a huge problem, namely, the amount of enormous information transmitted from each eye retina, which it should interact with and process. This, of course, will cause an enormous strain on the visual system in processing vast amounts of information, some of them are important, and the rest is unimportant “for the person, his situation and his awareness at the moment”. So, what is the benefit of processing information that is not needed at present and will be dispensed later? Is it not better to dispense early before an effort to process it? (Snowden Robert, Thompson Peter, 2012).  4- Selection Here comes the role of the fourth step to filter the amount of information coming from the retina, where the optic nerve reaches the main relay point on the way to the cortex, which is the lateral geniculate nucleus, then to neurons designed to process the information coming from LGN to make it apparent. These neurons are specialized to respond to some features like orientation, spatial frequency, length, corners, and motion, so these neurons are called feature detectors (J., 2015). (Goldstein, 2014)  5- Organization After filtering the visual information, the fifth step is reorganizing the visual information to become meaningful through classification so that it can be distinguished. Categorization is the process of identifying things that belong to each other and grouping them according to the same category of stimuli. This process is done through the search for constants, despite any differences in the appearance and orientation of objects, therefore, leading to abstraction, which in turn leads to generalization. Then comes the ability to distinguish between objects belonging to a class and their non-affiliation to another category of stimuli, which is called discrimination (Goldstein, 2014).  5- Organization There are several explanations of the organization’s process through specific visual principles such as perceptual constancy, depth and distance cues, and gestalt approach to perceptual grouping (perception of groups) (Sternberg et al., 2012).  The principles of visual perception Selection and Gestalt principles of Depth perception organization of visual perceptual organization stimuli Monocular Binocular The phi phenomenon Perceptual constancies depth cues depth cues Accommodation Retinal Figure-ground organization Size constancy disparity Pictorial depth Convergence Closure Shape constancy cues Linear perspective Similarity Color constancy Interposition Texture gradient Proximity Brightness constancy Relative size Height in the visual field © Dr. Tarek Bahaa El-deen (Goldstein, 2014) (Goldstein, 2014)  6- Interpretation After organizing the visual information to become meaningful, it comes the role of step six is to explain and define this visual information and to judge and interact with it as real existent objects. Human tends to assume that their concept of things is accurate and sufficient and enables them to interact with the surrounding environment appropriately, and this perception is consistent with the actual reality of objects. However, there are many phenomena as in visual illusion, which show that perception is not veridical but are interpretative processes (Call, 2017).  6- Interpretation “Interpretation is influenced by several factors, including perceptual adaptation, perceptual set, the frame of reference, and bottom-up or top-down processing. Past experiences, assumptions, values, and expectations help us interpret what we are looking at by contributing to our perception” (Call, 2017). https://indulgy.com/do The six stages of visual perception Reception Transduction Transmission Selection Interpretation Organization  REFERENCES Balcetis, E., & Dunning, D. (2006). See what you want to see: Motivational influences on visual perception. 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