Chapter 2

Glossary

Active perception Perception as a function of interaction with the world.

Attention conspicuity The interaction of aspects of a stimulus (such as colour, luminance, form) with aspects of an individual (such as attention, knowledge, preconceptions) that determine how likely a stimulus is to be consciously perceived. (See also sensory conspicuity.)

Binaural cues Cues that rely on comparing the input to both ears, as for example in judging sound direction.

Constructivist approach Building up our perception of the world from incomplete sensory input. (See also

perceptual hypotheses.)

Direct perception Perception without the need for top-down processing.

Dorsal stream A pathway which carries visual information about the spatial location of an object (also known as the ‘where?’ pathway).

Features Elements of a scene that can be extracted and then used to build up a perception of the scene as a whole. (See alsogeons.)

Geons Basically features, but conceived explicitly as being 3-D features.

Haptic perception Tactile (touch) and kinaesthetic (awareness of position and movement of joints and muscles) perception.

Illusions Cases in which perception of the world is distorted in some way.

Knowledge Information that is not contained within the sensory stimulus.

Laws of perceptual organisation Principles (such as proximity) by which parts of a visual scene can be resolved into different objects.

Numena The world as it really is. (See also phenomena.)

Pandemonium A conceptual model of a feature extraction process.

Parallel distributed processing (PDP) approaches Stimuli are represented in the brain, not by single neurons, but by networks of neurons. An approach sometimes used to model cognitive processes.

Perception The subjective experience of sensory information after having been subjected to cognitive processing.

Perceptual hypotheses An element of the constructivist approach, in which hypotheses as to the nature of a stimulus object are tested against incoming sensory information.

Phantom word illusion What we hear may be influenced by what we expect to hear.

Phenomena Numena as we perceive them.

Phenomenological experience Our conscious experience of the world.

Primal sketch First stage in Marr’s model of vision, which results in computation of edges and other details from retinal images.

Proprioception Knowledge of the position of the body and its parts (arms, fingers, etc.). (See also

haptic perception.)

Re-entrant processing Information flow between brain regions (bidirectional).

Reversible figure A figure in which the object perceived depends on what is designated as ‘figure’ and what is designated as ‘(back)ground’.

Sensation The ‘raw’ sensory input (as compared with perception).

Sensory conspicuity The extent to which aspects of a stimulus (such as colour and luminance) influence how easily it can be registered by the senses. (See also attention conspicuity.)

Size constancy The perceived size of objects is adjusted to allow for perceived distance.

Spectral cues Auditory cues to, for example, distance provided by the distortion of the incoming stimulus by (e.g.) the pinnae (ear lobes).

Templates Stored representations of objects enabling object recognition.

Three-dimensional (3-D) sketch Third stage in Marr’s model of vision. This is a viewer-independent representation of the object which has achieved perceptual constancy or classification.

Two-and-a-half-dimensional (2.5-D) sketch Second stage in Marr’s theory of vision. Aligns details in primal sketch into a viewer-centred representation of the object.

Ventral stream A pathway in the brain that deals with the visual information for what an object is (also known as the ‘what?’ pathway).

Visual masking Experimental procedure of following a briefly presented stimulus by random visual noise or fragments of other stimuli. Interferes with or interrupts visual processing.

Summary

There are a number of theories that attempt to explain how we encode incoming sensory information.
Perception is not the same as sensation. We may detect something but not perceive it.
Knowledge is unnecessary in our perception of the world – according to direct perception theories.
Knowledge is crucial in our influencing our perception of the world – according to constructivist theories.
Both approaches may operate in vision with the ventral stream operating primarily for perception for recognition and the dorsal stream operating primarily for perception for action.
Knowledge is also crucial in auditory perception.
There are strong interactions between auditory and visual perception.
There may be at least twenty-one senses (not just five!).
Knowledge also influences haptic perception.
We sense things not as they are, but as we are.