Visual system The visual system in animals allows individuals to assimilate information from their surroundings. The act of seeing starts when the cornea and then the lens of the eye focuses light from its surroundings onto a light-sensitive membrane in the back of the eye, called the retina.
Saul McLeodpublished In order to receive information from the environment we are equipped with sense organs e. Each sense organ is part of a sensory system which receives sensory inputs and transmits sensory information to the brain. A particular problem for psychologists is to explain the process by which the physical energy received by sense organs forms the basis of perceptual experience.
Sensory inputs are somehow converted into perceptions of desks and computers, flowers and buildings, cars and planes; into sights, sounds, smells, taste and touch experiences.
A major theoretical issue on which psychologists are divided is the extent to which perception relies directly on the information present in the stimulus.
Some argue that perceptual processes are not direct, but depend on the perceiver's expectations and previous knowledge as well as the information available in the stimulus itself. This controversy is discussed with respect to Gibson who has proposed a direct theory of perception which is a 'bottom-up' theory, and Gregory who has proposed a constructivist indirect theory of perception which is a 'top-down' theory.
Psychologists distinguish between two types of processes in perception: Bottom-up processing is also known as data-driven processing, because perception begins with the stimulus itself.
Processing is carried out in one direction from the retina to the visual cortex, with each successive stage in the visual pathway carrying out ever more complex analysis of the input. Top-down processing refers to the use of contextual information in pattern recognition.
For example, understanding difficult handwriting is easier when reading complete sentences than when reading single and isolated words.
This is because the meaning of the surrounding words provide a context to aid understanding. Gregory and Top Down Processing Theory Psychologist Richard Gregory argued that perception is a constructive process which relies on top-down processing.
Stimulus information from our environment is frequently ambiguous so to interpret it, we require higher cognitive information either from past experiences or stored knowledge in order to makes inferences about what we perceive. For Gregory perception is a hypothesis, which is based on prior knowledge.
In this way we are actively constructing our perception of reality based on our environment and stored information. Therefore, the brain has to guess what a person sees based on past experiences. We actively construct our perception of reality. Richard Gregory proposed that perception involves a lot of hypothesis testing to make sense of the information presented to the sense organs.
Our perceptions of the world are hypotheses based on past experiences and stored information. Sensory receptors receive information from the environment, which is then combined with previously stored information about the world which we have built up as a result of experience.
The formation of incorrect hypotheses will lead to errors of perception e. Evidence to Support Gregory's Theory Highly unlikely objects tend to be mistaken for likely objects Gregory has demonstrated this with a hollow mask of a face see video below.
Such a mask is generally seen as normal, even when one knows and feels the real mask. There seems to be an overwhelming need to reconstruct the face, similar to Helmholtz's description of 'unconscious inference'.
An assumption based on past experience. Perceptions can be ambiguous The Necker cube is a good example of this. When you stare at the crosses on the cube the orientation can suddenly change, or 'flip'.
It becomes unstable and a single physical pattern can produce two perceptions. Gregory argued that this object appears to flip between orientations because the brain develops two equally plausible hypotheses and is unable to decide between them.
When the perception changes though there is no change of the sensory input, the change of appearance cannot be due to bottom-up processing. It must be set downwards by the prevailing perceptual hypothesis of what is near and what is far.
Perception allows behavior to be generally appropriate to non-sensed object characteristics For example, we respond to certain objects as though they are doors even though we can only see a long narrow rectangle as the door is ajar. What we have seen so far would seem to confirm that indeed we do interpret the information that we receive, in other words, perception is a top down process.
Critical Evaluation of Gregory's Theory 1. The Nature of Perceptual Hypotheses If perceptions make use of hypothesis testing the question can be asked 'what kind of hypotheses are they? In some cases it would seem the answer is yes.
For example, look at the figure below: This probably looks like a random arrangement of black shapes. In fact there is a hidden face in there, can you see it? The face is looking straight ahead and is in the top half of the picture in the center.
Now can you see it? The figure is strongly lit from the side and has long hair and a beard. Once the face is discovered, very rapid perceptual learning takes place and the ambiguous picture now obviously contains a face each time we look at it.According to McMaster University, the goal of perception is to be able to understand the world around us using our sensory stimuli and we develop our own experiences.
occlusion Indeterminates: size, distance, shape, orientation, light source, reflection & shadow Importance of. Importance Of Visual Perception In Cognitive Processes.
A 3 page paper written in bulleted outline form. The paper identifies the relationships between visual perception and cognitive processes and how visual perception is used. The sections discuss perception and visual search, improving attention, bottom up-top down, and perception and.
Gibson () argued that perception is a bottom-up process, which means that sensory information is analyzed in one direction: from simple analysis of raw sensory data to ever increasing complexity of analysis through the visual attheheels.com: Saul Mcleod.
Visual perception is the ability to interpret the surrounding environment using light in the visible spectrum reflected by the objects in the environment. The resulting perception is also known as visual perception, eyesight, sight, or vision (adjectival form: visual, optical, or ocular).
Read this article to learn about the meaning, nature and importance of perception. Meaning and Definition of Perception: “Perception is the process through which the information from outside environment is selected, received, organised and interpreted to make it meaningful to you.
This essay will discuss the foundations of cognitive psychology and the relevant theories behind this statement above, such as attention, selective visual attention, Perception, and visual search processes for consumers.