perception

PerceptionL4

Prof. Dr. Elham Al-Jammas May 2015

Perception

the conscious mental registration of a sensory stimulus

Recognition and interpretation of sensory stimuli based chiefly on memory.

the conscious recognition and interpretation of sensory stimuli that serve as a basis for understanding, learning, and knowing or for motivating a particular action or reaction.
the result or product of the act of perceiving

Kinds of perception

Include: Depth perception, extrasensory perception, facial perception and stereo gnostic perception.
Depth perception the ability to recognize depth or the relative distances to different objects in space.


extrasensory perception (ESP)
knowledge of, or response to, an external thought or objective event not achieved as the result of stimulation of the sense organs A. Telepathy or thought transference from one person to anotherB. Clairvoyance , visual perception of an object that is covered or sealedC. Precognition or perception of a future events

psycho kinesis (PK)

manipulating object without touching them

Process Perception

Can be defined as the active process of selecting, organizing, and interpreting the information brought to the brain by the senses

HOW THEY WORK together

Sensory organs absorb energy from a physical stimulus in the environment
Sensory receptors convert this energy into neural impulses and send them to the brain perception follows
The brain organizes the information and translates it into something meaningful

But what does "meaningful" mean? How do we know what information is important and should be focused on
Selective Attention - process of discriminating between what is important & is irrelevant (Seems redundant: selective-attention?), and is influenced by motivation
ALL OF THIS IS CALLED Psychophysics

Psychophysics can be defined as, the study of how physical stimuli are translated into psychological experience.
In order to measure these events, psychologists use THRESHOLDs
Threshold - a dividing line between what has detectable energy and what does not.
Difference Threshold - the minimum amount of stimulus intensity change needed to produce a noticeable change.
the greater the intensity (ex., weight) of a stimulus, the greater the change needed to produce a noticeable change


Signal detection theory
The sensory ability of the observer
Selectivity of the observer
Expectancy & individual internal needs & interest
Fatigue and exhaustion
The urgency of the moment
Constancy of size shape and brightness

The Gestalt principles of grouping include four types: similarity, proximity, continuity, and closure.

Disorder of perception

I.sensory distortion
1. Changes in intensity (hyper acusis )
2.Change in quality ( xanthopsia , erythropsia,chloropsia )
3.Change in special form (micropsia , macropsia )

II. Sensory deception

Hallucinations (imaginary perceptions). Hallucinations and illusions are often classed together under the name of psych sensory disorders

hallucination

A perception, which feels real, but has no real stimulus
usually abnormal, especially when persistent
But occasional hallucinations are more common than we thought! - 10% of British population, at some time
Modalities:

Auditory

heard as if coming from outwith your head (including from another part of the body) cf pseudohallucinations
Visual (more indicative of organic pathology!)

Olfactory

Somatic / (visceral) / Sexual


Gustatory

hallucination2

Non-pathological:
Hypnagogic (going off to sleep)
Hypnopompic (waking up)

illusion

Incorrect perception of a real stimulus (in any modality)
Usually non-pathological
Bush looks like a killer in the dark
“cocktail party” illusion: hearing your name across a noisy room
A stray hair may feel like a spider on the neck
BUT illusions occur in psychosis
eg girl complains her face is melting when she looks in mirror

Insufficiency Of Perception

Insufficiency of perception in its slightest degree may be met with in states of depression, at the onset of confusional states, etc. All external impressions are vague, uncertain, and strange. The patients complain that everything has changed in them and around them: objects and persons have no more their usual aspect; the sound of their own voice startles them.
Finally, complete paralysis of one or several forms of psych sensory activity is observed in connection with profound disorders of consciousness, as in mental confusion of the stuporous form

Insufficiency of perception constitutes an important element of clouding of consciousness

Illusion
Is misperception or misinterpretation of external stimuli

Thank you