Perception. Supervision Prof. Dr. Ramez N. Bedwani. Outcomes giving meaning to external stimuli is affected by external factors ( symbols and signals) and internal factors (receptors, habit, set, attitude). Faulty perception occurs both in normal and diseased persons. Perception.
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Prof. Dr. Ramez N. Bedwani
Faulty perception occurs both in normal and diseased persons.
Stimuli received from the object e.g. smoke is a signal for fire.
Similar stimuli tend to be grouped together.
Proximate objects tend to be grouped together.
Stimuli tend to be grouped together in order to perceive a defective whole as a closed one.
For example asymmetric triangles are liable to be perceived as symmetrical ones. (see figure)
There is a tendency to perceive the poor figure as if they were exact and good.
6. Good continuation:
In the figure we see how we tend to continue lines to make rectangles instead of perceiving lines separately.
7. Competition and cooperation of grouping tendencies.
In every stimulus pattern the elements of stimulus have some degree of proximity , similarity, continuity etc. At a time all kind of grouping tendencies are at work. (Sometimes they work in the same direction of or- .and sometimes they compete with one another lowest figure)
Our mood influences markedly our perception e.g when you are sad you perceive every thing as bad
False perception of an external stimulus. may occur by factors in the individual, in the stimulus or in both
Déjà vu phenomenon: illusion of familiarity: the person feels that he has previously experienced what he is experiencing at the present time.
Hallucinations: are mental impressions of sensory vividness occurring without external stimulus.
occur normally or under experimental conditions:
In pathological conditions hallucinations are met with in the following examples:
The organism is preparing himself to the act that the he will soon perform. e.g. an athlete runner is training daily for physical fitness and developing skills.
2. The set to start:
You know what is going to happen and you prepare yourself to start reacting to a specific stimulus (e.g. runner on the mark waiting to listen to the pistol shot to start)
3. The set to continue: It means that the activity continues towards the goal.
This refers to the sets when the task is predominantly mental such as studying or solving a mathematical problem
2. Situational set:
The set differs according to the situation e.g. A singer singing to himself in the bath room performs differently from when singing to his audience in a theatre
It is the time that elapses between receiving a stimulus and responding to it. It differs with the type of reaction which could be:
Here the individual knows the single stimulus he will receive and the single response he has to make e.g. to press a button on hearing a signal. It usually lasts for 0.14 sec for a sound or a touch and 0.18 sec for light.
That reaction corresponds to our behavior in everyday life expecting the next green traffic lights.
The individual is required to make certain different responses to specific different stimuli e.g. raise right hand whenever a red light is shown its duration is usually 0.24 sec for sound and 0.28 for light
This reaction corresponds to our behavior in everyday life in playing tennis
The individual knows nothing about the definite specificity of the coming stimulus, although he knows its nature and the rule how to respond.
This reaction corresponds to our behavior in everyday life in answering questions in mathematical problems in spotting slides under the microscope or in MCQ examinations.
All correct except one
1. Extroceptor are
2. We perceive
3. Faulty perception