psychobiological processes - perception Flashcards
Sensation is:
the first awareness of some outside stimulus. An outside stimulus activates sensory receptors, which in turn produce electrical signals that are transformed by the brain into meaningless bits of information.
Perception is:
the experience we have after our brain assembles and combines thousands of individuals, meaningless sensations into a meaningful pattern or image. rarely exact replicas of the original stimuli changed = biased, coloured, or distorted by our unique set of experiences. Thus, perceptions are our personal interpretations of the real world.
Bottom-up theory:
are when stimuli are first recognized and then built up, with memory and existing schemata, into higher-order perceptions.
Top-down theory:
perceptions begin with the most general and move toward the more specific. These perceptions are heavily influenced by our expectations and prior knowledge
Bottom-up theorist:
Gibson (1966)
Gibsons bottom-up theory is defined as:
processing information by starting with the individual elements of a visual stimulus and gradually building up a final representation. Gibson believes that perception occurs from sensation.
Gestalt principles of visual perception refer to the:
numerous ways in which we organise the elements in our visual field by grouping them into the perception of a whole, complete form, usually in the simplest possible way.
When we use figure-ground, we:
organise visual information by perceptually separating important aspects of the visual field into the ‘figure’, which stands out from the ‘ground’, (the surroundings).
Closure refers to the:
perceptual tendency to mentally ‘close up’, fill in or ignore gaps in a visual stimulus and to perceive objects as complete.
The principle of similarity involves the:
tendency to perceive stimuli or parts of a visual stimulus that have similar features such as size, shape, texture or colour-as belonging together in a unit, group or ‘whole’.
The principle of proximity is the tendency to:
perceive parts of a visual stimulus that are positioned close together as belonging together in a group.
Navon (1977) conducted a study to examine:
examine the distinction between “global and local” features of stimulus patter. Participants were required to observe a large letter (Global) that was made up of small letters (Local) in 2 conditions.
Feature detector theory by:
Hubel and Wiesel (1962)
The feature detector theory found:
that certain neurons in visual cortices of cats responded to specific features of images received at the brain, but not to other features. Their research suggests tiny pieces of the visual stimulus are individually detected and assembled in the visual cortex.
Depth cues are:
information from the environment (external cues) or from within our body (internal cues) that help us to perceive how far away objects are. DC provide the information that enables us to translate the 2D images into 3D reality. DC can be categorised in terms of whether they are binocular or monocular.
Binocular depth cues use:
both eyes working together in order to provide information to the brain about depth and distance. Bi DC important in determining distance of objects relatively close and if one eye limited tasks requiring focus short distance difficult.
Retinal disparity refers to the:
very slight difference in the location of the visual images on the retinas, which enables us to make judgments about the distance of an object from the viewer. When the two different retinal images are fused in the brain, the images received from each eye are compared and any disparity between the two images provides information about the depth of the object or its distance from the viewer.
Convergence involves the:
brain detecting and interpreting depth or distance from changes in tension in the eye muscles when the two eyes turn inwards to focus on nearby objects. The brain interprets greater tension object closer and less tension object further away.
Gregory (1970) stated that:
perception is a constructive process that depends on top-down processing.
Monocular depth cues are:
cues that require the use of only one eye to provide information to the brain about depth and distance, but they also operate with both eyes.
Monocular depth cues include:
accommodation, and pictorial cues such as linear perspective, interposition, texture gradients, relative size and height in the visual field.
Accomodation involves the:
automatic focusing mechanism of lens in eye to adjust the shape of lens in response to differing distances of view from the object. Lens bulges to focus on nearby objects and elongates focus on distant objects.
Pictorial cues are used to:
portray depth and distance on a 2D surface
Linear perspective is the:
apparent convergence of parallel lines as they recede into the distance. Narrowing disappearing parallel coming together ‘vanishing point’.
