Basic Principles of Visual and Auditory Perception

Gestalt (visual) perception:

Perceptual organization is defined as the ability to cognitively organise sensory data. Gestalt psychologists pointed out that this sort of organization is crucial for the functioning of visual and auditory perception. Very importantly, the perceptual organisation is orderly and not random, as also indicated by the word ‘Gestalt’, which means ‘organised structure’ in German. Gestalt psychologists supported that perceptual organization consists of procedures of grouping and segregation (Pratt & Koffka, 1936). Among the factors that govern figure-ground separation, they identified size, contrast, symmetry etc. That is, even if humans experience a complex world, where different entities have different characteristics, (ex. colour, textures, constancy, contours), our perception system is made in a way that perceives objects in a structured way.

Gestalt psychology has made big contributions to understanding visual perception. It has been crucial to distinguish between sensation and perception. Both ‘top-down’ and ‘bottom-up’ processing is likely to occur in perception. Illusions are erroneous concepts, and there is still a lot of conjecture as to how best to ‘explain’ or understand why they occur.

Visual perception is the ability to perceive the surrounding world using light in the visible spectrum reflected by objects in the environment through photopic vision (daytime vision), colour vision, scotopic vision (night vision), and mesopic vision (twilight vision). This is distinct from visual acuity, which refers to how well a person can see (for example, “20/20 vision”).  Even if a person has 20/20 vision, they can have issues with visual perceptual processing.

Figure-ground differentiation: is a perceptual grouping that is required for visual object recognition. Identifying a figure from the backdrop is a term used in Gestalt psychology. For example, the “figure” is black lettering on printed paper, and the “background” is a white sheet.

Visual object constancy: is the capacity to recognise an object by its image despite variation in the image when the object is seen from multiple angles.

Visual pathway:

Auditory perception:

Auditory perceptual organisation is more complex than visual perceptual organisation. For instance, if two items are in the same line of sight for the observer, one will obscure the other for the viewer, thus facilitating the viewing of one object and its properties but obscuring the vision of the other. In this case, the observer can at least observe one item and notice its properties correctly. In addition, when there are two events occurring at the same time, they often mingle together and reach the listener’s ear as one sound wave. In this case, it is difficult for the listener to differentiate one sound from the other. Therefore, the segregation and localisation of sounds is a more complex process than the grouping and segmentation of events in a visual scene. Even if the listener manages to distinguish the sounds, categorising a sound event is more difficult than categorizing a visual event. This is because sounds are hardly ever distinguishable by the existence of discrete features, but by their multiple auditory dimensions (Holt and Lotto, 2006).

Auditory pathway:

Set and other aspects of perceptual organisation:

You could believe that what you see is what you get when it comes to our impressions of the world around us. However, research reveals that your own past experiences, expectations, motivations, beliefs, emotions, and even culture all have a strong influence (and bias) on how you perceive the world (Biggs, 2015). A perceptual set is basically a tendency to view things only in a certain way.

A perceptual set is an excellent example of top-down processing. Perceptions in top-down processing begin with the most general and progress toward the more detailed. Expectations and prior information have a strong influence on such impressions. When we expect something to appear in a certain way, we are more likely to see it in that manner.

Example of Forces of Influence:	Summary:
Motivation can influence perceptual sets and how we understand our surroundings	We may be motivated to regard members of the opposite side as too aggressive, weak, or inept if we are supporting our preferred sports team. In one classic experiment, subjects were denied meals for several hours. Those who had gone without eating were considerably more likely to identify ambiguous images as food-related objects when they were presented with them later.  They were more driven to see the visuals in a specific way because they were hungry (Sanford 1936).
Expectations have a crucial influence as well	If we expect others to behave in specific ways in certain situations, our perceptions of these people and their jobs will be influenced. One of the most well-known tests on the effect of expectation on perceptual sets involved presenting subjects with a series of numbers or letters.  The subjects were next presented with an ambiguous visual that might be read as either the number 13 or the letter B. Those who looked at the numbers were more likely to see it as a 13, but those who looked at the letters were more likely to see it as the letter B (Bruner 1955).
Culture also shapes our perceptions of people, objects, and circumstances	Surprisingly, researchers discovered that people from various cultures perceive perspective and depth cues differently (de Bruine, 2015).
Emotions can have a significant impact on how we view our surroundings	When we are furious, we are more prone to detect antagonism in others. One investigation found that when subjects became accustomed to associating a nonsense syllable with minor electrical shocks, they experienced physiological responses to the syllable even when it was provided subliminally (Murre, 2015).
Attitudes can also have a powerful influence on perception	Gordon Allport demonstrated that prejudice could have an influence on how quickly people categorize people of various races (Barlow, 2013).

Visual and Auditory Development in Children

In the 1960s experiments were carried out on monocularly-deprived kittens which demonstrated that for the optic cells to develop fully and allow full binocular vision, then both eyes need to be receiving input during early life. This suggested a critical period in early life for visual development. The visual system retains a degree of plasticity, which becomes ‘hardwired’ as we become adults. The first 5 years of life are the most critical. The critical period appears to be complete by the ages of 7-9 years old.

Research has shown that hearing is essential for the development of speech. Alongside the visual critical period is a critical period that exists for vocal learning.

Visual and auditory impairment in children does not significantly affect IQ, but creates unique challenges nonetheless.

Perception as an Active Process

According to Piaget (1953) visual perception is very limited at birth and therefore the development of perceptual capabilities is a result of an intensive and gradual process of learning in the first months after birth. Hebb (2012) described the different stages of perceptual development starting from the dominance of colour, to gradually ending at the recognition of an object as a whole through the employment of attention to the distinct parts of an item. Moreover, Piaget’s constructionist theory supported that perception has to develop in a structured way so that the human brain can understand the surrounding reality. Therefore, he saw perception as an active process, humans’ sensory system and brain are actively engaging in visual stimuli and are gradually becoming more competent at recognising and classifying an object and its properties.

The Development of Visual Perception as an Illustration of Environmental Interaction

When we enter a visual environment, we get an impression of its objects, and we take context-specific actions. The question at this point is how visual perceptions evolve over time. Research has frequently searched for answers by examining the perceptual system of infants. Are infants born with a sufficiently organised visual system, which is able to group shapes, colours and textures into coherent shapes, or does it undergo a period of gradual development and maturation, where experience helps them notice and analyse visual information, in order to make context-appropriate interpretations? (Gibson. 1979)

Another theory of visual perceptual development supports that the infant’s ability to cognitively distinguish different categories of stimuli is associated with the requirements of their environment. In line with this, one key observation showed that infants 9-12 months of age were more able to differentiate and maintain in their memory visual stimuli that they encountered more often, compared to stimuli they viewed less frequently. (Scott, et al, 2007).

During this first year of life, the visual system, and the brain undergo dramatic development. More importantly, there is a reciprocal interaction between these physical changes and the environment. Through this interaction, humans gradually form perceptual representations of their surrounding visual world. Therefore, experience plays a key role in the maturation of the visual perceptual system.

References:

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