Cognition and Perception

Published on 03/03/2015 by admin

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Last modified 03/03/2015

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Cognition and Perception

What are cognition and perception?

Perception

Perception is the organization, integration and interpretation of sensory stimuli (S3.23) to provide meaningful information. Perception may not be a direct record of the environment surrounding us because meaning is constructed by our brains based on learning and previous experience and is therefore highly individual. This complex processing involves many areas of the brain including the sensory association areas of the parietal lobe (S2.7).

Cognition

Cognition is the ability to process, retrieve and manipulate information. Cognition for the most part is localized in the frontal lobe of the cerebral cortex (S2.7), however these specific areas interact with many other areas of the brain, making processing highly complex. Emotion is now also considered a cognitive process.

Perception and cognitive functions are essential for efficient interaction with our environment and have been found to have an impact on both movement and posture with impairments noted as a poor prognostic indicator in the population of neurologically impaired patients. The list below shows the hierarchical arrangement of normal perceptual and cognitive processes. Note that the higher levels of the hierarchy depend upon the lower levels as part of their construct:

• Executive function

• Recognition

• Body schema

• Basic perception

• Sensory registration.

Sensory registration

This incorporates the ability to receive and modulate sensory information and is a prerequisite for perception. Patients with a sensory impairment are therefore likely to experience some perceptual/cognitive problems.

Attention

This ability is related to how we become receptive to our sensory environment and allows us to restrict our attention to what is relevant at the present time. This is vital when considering the constant bombardment of our sensory systems. Deficits related to attention are usually associated with damage to the right hemisphere and common presentations include poor attention span and being easily distracted.

Five levels of attention have been identified:

Focused attention: The ability to focus on one stimulus

Sustained attention: The ability to maintain attention over a period of time, often referred to as attention span

Selective attention: The ability to focus on a specific stimulus, while filtering out any non-relevant stimuli (distractions)

Switching attention: The ability to switch focus between two or more stimuli

Divided attention: The ability to respond to more than one stimulus at one time. For example, talking while walking. This ability is easier when the stimuli are from different sensory modalities.

Basic perception

This includes the processing/interpretation of all sensory modalities:

Touch perception (stereognosis): This is the ability to interpret information using only tactile and proprioceptive sensation.

Visual perception:

Visual processing allows us to interpret and organize visual information. This processing occurs primarily in the visual association areas of the occipital, parietal and temporal lobes (S2.7) (Kandel et al. 2000). There are two main aspects to visual perception:

Visuoperceptual: This involves the interpretation of the form of an object, such as colour, texture, shape, size and includes size and form constancy. Form and size constancy are the ability to recognize the same object even when it is in a different context or of a different size.

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