Observation is the capacity of the individual to know the environment by the use of his senses. There are two steps in the process of observation:

Transcription

1 Definition Observation is the capacity of the individual to know the environment by the use of his senses. There are two steps in the process of observation: 1) Attention: is the preparatory step, the getting ready to observe. 2) Perception: is the final step, i.e., the actual observing of some fact.

2 OBSERVATION

3 PERCEPTION

4 Definition Perception is the process of comparing the received sensation to the previously available information it includes the possibility of acquiring new information as the result of the interaction between the inside and outside in other words

5 FIELDS OF PERCEPTION 1- Perception of external environment: In this field we perceive objects and relations between them we also perceive sounds, distances and time. In addition to such material objects we perceive ideas, conclusions and concepts and those tools of abstract thinking.

6 2-Perception of internal environment We perceive much about our body with its components, our psyche with its mechanisms

7 Nature of the Stimuli Perceived 1. Symbols: are arbitrary names standing for objects, the name orange stands for a certain known fruit. 2. Signals: are stimuli coming directly from the object, smoke is a signal of fire. 3. Concepts: are the meaning of words and the facts elicited from external stimuli.

8 NEUROPHYSIOLOGY OF PERCEPTION Perception occurs in the psychic areas these are areas 5 & 7 for sensory perception, areas 18 & 19 for visual perception, area 22 for auditory perception, and the entorhinal area for olfactory perception

9 Perceptual Constancy Perceptual Constancy perceiving objects as unchanging even as illumination and retinal image change color shape size

10 Perceptual Organization Figure and Ground--organization of the visual field into objects (figures) that stand out from their surroundings (ground)

11 Organization: Grouping the perceptual tendency to organize stimuli into coherent groups Grouping Principles proximity--group nearby figures together similarity--group figures that are similar continuity--perceive continuous patterns closure--fill in gaps connectedness--spots, lines, and areas are seen as unit when connected

12 Organization: Perceptual Grouping Principles

13 Organization: Closure Perceptual Gestalt grouping principles are at work here.

14 Perceptual Illusions

15 PERCEPTUAL ORGANIZATION A- Stimulus factors (figural factors) Which are factors that favor the organization of a stimulus pattern and the build up a figure out of them. -The relation between figure and ground, the part which stands out of the stimulus pattern is called the figure and the rest figure the ground. When we perceive an object usually one part tends to stand out while the rest seems to remain in the background e.g. the letters on the page as a whole.

16 2-Building up of a figure The factors that favor the organization of a stimulus pattern to build a figure out of them: a) Similarity: one perceives similar colors and shapes as if gathered together. b) Proximity: one perceives things near to other as if forming a unity. c) Good form: the stimuli that form a good figure will have a tendency to be grouped, this grouping could be established by continuity, symmetry, closure or approximation.

17 1) Continuity: This means that there is natural resistance to break the continuous flow of a line, pattern or design in our perceptual awareness. 2) Symmetry: Grouping which will lead to symmetrical or balanced wholes are received favorably as Good form in contrast to a symmetrical ones.

18 3) Closure: is the grouping of elements in such away so as to take a more closed or more complete figures. 4) Approximation: there is a tendency to perceive the poor forms as if they are good forms (Praganan s law) e.g. broken circles tend to be perceived as complete circles.

19 D) Competition and co-operation of grouping tendencies

20 B- Internal factors (personal factors) 1. Habit and familiarity: retained past experience and habit, make it easy to perceive similar objects. 2. Set: is selective preparedness to perceive certain figures or objects according to our interest and expectation at the moment.

21 3. Aesthetic factor: is the individual s tendency to perceive pleasing and beautiful and disregard irregular, meaningless and ugly ones. This depends on the critical ability of the individual. 4. Emotions: Feeling and emotions influence one s capacity for accurate or objective perceptions e.g., lovers disregard the faults and defects of the beloved person.

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23 5. Drive and motivations: Individuals are prone to errors of perception when influenced by a strong drive or emotion e.g. the desert traveler suffering from intense thirst sees the mirage of a pool of water which turns out to be a sea of sand 6. Suggestion and hypnosis: These have a strong influence on susceptible individuals in causing distorted and false perceptions

24 PSYCHOPHYSICS OF PERCEPTION It includes measurement and description of the observer responses to specified stimuli 1. Accuracy of perception: perception depends on many factors and therefore its accuracy may be questioned, specially if the signs are ambiguous or unclear. 2. Perception of number (span of apprehension): it is the number or items which can be correctly estimated in a single glance without counting. The span depends on the observer grouping and the inherent observing capacity

25 3. Variable error of perception: if collections of 12 dots are shown to an individual, he is inclined to estimate them from 10 to 14 dots in repeated trials. This is called the variable error i.e. his estimation scatter on both sides of the true value. This variable error cannot be wholly eliminated but can be diminished by long practice. 4. Constant error of perception: is shown by the preponderance of shots to one side of the target of an inexperienced shooter. This error can be completely eliminated by practice.

26 5. Absolute threshold of perception: is the minimal value of the stimulus intensity which can be perceived. 6. Difference threshold: is the minimal value of decrease or increase in the quantity and quality of a stimulus which an individual can observe.

27 7. Weber s law: The size of the difference threshold is a constant proportion of the intensity of the stimulus provided that the stimulus values are moderate. The law can be stated in the following formula Weber s Law = Difference threshold Value of the stimulus = Constant.

28 Recent evidence dictates a Pover law that changes in the stimulus which produce equal stimulus ratios result in equal ratio of the reported stimulus e.g. the comparison of two car horns versus one is the same stimulus ratio as 20 car horns compared to 10 these comparisons would be judged to be equal. That is, 20 as compared to 10 to the same psychological ratio as 2 to 1.

29 8. Perceptual constancy: is the perception of an object and all of its properties as constant in spite of the continuously changing character of stimuli perceived by the sense organs. 9. Perceptual artifacts: Certain kinds of stimulus situations produce, not only immediate sensations and perceptions but also a further sensation after the stimulus has physically ceased. Commonly experienced after-effects are the visual glare which persists after a glance to the sun.

30 10.Extra sensory perception (ESP): An intriguing and persistent irritation to the psychology of perception is the belief that information may be transmitted through other channels than the knowing sensory mechanisms. The phenomena recorded are: A. A- Telepathy: Thought transmission from one mind to another. B. B- Clairvoyance: Knowledge of the happening at another time or place. C. C- Precognition: Prediction of future events. D. D- Psychokinesis: The ability to move objects by mental power. E. E- Color detection by touch without the aid of vision. F. These extrasensory perceptions have been found to be special powers of a few sensitive individuals rather than a general phenomenon of all individuals.

31 FAULTY PERCEPTIONS 1- Camouflage: Some animals and birds have the ability to change their colors in an attempt to conceal themselves from the eyes of their enemies. This process is called camouflage i.e. making others blind of their presence through faulty perception.

32 2- Illusions :are false perceptions of external stimuli. A. Illusions due to physical causes. B. Illusions due to habit and familiarity. C. Illusions due to set and expectation. D. Illusion due to unanalyzed total impressions

33 3-De Ja Vu and Jamais Vu Phenomena The former is present when the individual recognizes a foreign subject as familiar and the latter when he denies that he has seen something which was well known to him

34 4-Hallucinations Are mental impressions of sensory vividness in absence of external stimulus. Hallucinations may occur in any sensory modality A. Visual hallucinations: are characteristics of acute brain syndromes, they occur in acute schizophrenia B. Auditory hallucinations: especially characteristic of schizophrenia. C. Olfactory hallucinations: frequently occur as aura of psychomotor or temporal lobe epilepsy sometimes they occur in schizophrenia. D. Gustatory hallucinations: are rare although they usually represent the aura of convulsive disorder.

35 E. Tactile hallucinations: are more common than realized they are especially characteristic of brain syndrome and particularly of that type known as delirium tremens. When they take the form of bugs crawling on the skin it is called formication. F. Hypnagogic: hallucinations which occur when going to sleep. G. Hypnagogic: hallucinations which occur when coming out of sleep. H. Items 1 and 9 are normal hallucinations.

36 5-Depersonalization and Derealization Depersonalization is perceiving one s self as different Derealization is perceiving the world as different if chronic and intellectualized both phenomena become thoughts rather than perceptions