Attention Deficit

Attention Deficit/Hyperactivity Disorders (ADHD) affects about 5% of the population by conservative estimates and burdens adults as well as children. Various brain-scanning techniques including PET and SPECT scans indicate reduced metabolic activity in the frontal lobes. QEEG brainmaps also find a reduction in EEG activity in the frontal area of the brain. This excessive slow wave activity reduces the individual's ability to control and inhibit the brain and related nervous system activity. Impulsivity in motor and attentional centers of the brain results in impulsive behaviors and inappropriate responses to situations due to lost information during communications and general information gathering processes. Individuals are always trying to piece together what is going on after events and communications take place because they often lose key pieces of information. Consequently their performance suffers greatly in most contexts. They experience the world as overwhelming and over-critical of their actions. Children with ADD usually suffer from low self-esteem, anxiety, and often depression.

Picture Case Study: Ron was 14 years old and on 10mgs of Ritalin three times a day. Other medications had proven ineffective. He was acting out in class, oppositional with parents and teachers, forgetting books and assignments, having difficulty staying on task when reading, and suffering from comprehension and memory problems. He was also hanging around the kids who were in trouble at school all the time and his parents were concerned he would get into more trouble and become involved with drugs. Ron received 26 sessions of neurofeedback while his parents received training in parenting skills at the same time. His sessions included 8 sessions of alpha training to reduce his anxiety and oppositional nature followed by 18 sessions of beta training to increase the amount of activity and speed of processing in the frontal lobes. He was conditioned to increase beta while reading a textbook. By the fifth session Ron reported that his friends didn't like him anymore because he was different; too calm and unresponsive to their fooling around. He started hanging out with a nicer crowd of kids. His parents noticed changes in his behavior at home around the same time. By session 15 he was on 5mgs of Ritalin and his classroom behavior and schoolwork were improving. His anger and oppositional behavior had diminished to the point where it was no longer a problem. By session 24 he was off the Ritalin and a one year follow up found that he was still doing well and not on Ritalin.

Research: The research on ADHD is plentiful and well designed. Many group studies have been done and several clinics doing neurofeedback have large client databases to support their claims. The research indicates that neurofeedback is effective in 60-70% of cases. The milder the symptoms, the more effective it seems to be. Most cases require about 30 sessions of neurofeedback but difficult cases can require twice as many sessions. Few MDs, psychologists, and professional health people are aware of the existing studies or the clinical outcome studies of this intervention.

What is Eye Movement Desensitization and Reprocessing (EMDR)?

"EMDR (Eye Movement Desensitization and Reprocessing) therapy has emerged as a procedure to be reckoned with in psychology. Almost a million people have been treated. Also, further research appears to support the remarkable claims madefor EMDR therapy."

Reported in The Washington Post, July 21, 1995

In 1995, the American Psychological Association Division 12 (Clinical Psychology) initiated a project to determine the degree to which therapeutic methods were supported by solid empirical evidence. Independent reviewers placed EMDR on the list of "efficacious and empirically validated treatments."

What is EMDR?

Eye Movement Desensitization and Reprocessing (EMDR) is a non-drug, non-hypnosis, psychotherapy procedure discovered in 1987 by Dr. Francine Shapiro, a clinical psychologist. EMDR is a unique treatment practiced by thousands of clinicians world wide, treating a wide variety of issues with diverse populations.

Why does EMDR work?

EMDR is used to treat troubling symptoms such as anxiety, depression, guilt, anger, work-related stressors, and the effects of PTSD. It can also be used to enhance emotional resources such as negative self-esteem, lack of confidence, heighten learning and enhance personal performance. Science has not offered a conclusive answer as to why EMDR works but there have been extensive studies and continued research which is now beginning to point out how information is processed in the brain.
The model for EMDR presumes that everyone has the internal information processing system that is psychologically geared to move toward a state of mental health, just as the body is physiologically geared to heal itself. When something happens to us it bothers us. We think about it, we talk about it, we sometimes dream about it, and suddenly it doesn't bother us any longer. Our internal information system takes the information and processes it to an adaptive resolution.
It is theorized that when a traumatic or disturbing incident occurs, our natural internal system becomes unbalanced. The perception that exists at the time of the incident, whether seen, heard, felt, or thought, sends sensations to the brain that may end up locked in the nervous system. This can cause the system to be unbalanced; thoughts, feelings, and sensations remain in the memory network and continue to be triggered from either an internal or external stimulus creating unwanted feelings or behaviors.
EMDR appears to stimulate the normal brain processing of traumatic emotional experiences that have become locked in the nervous system. There is evidence that there is a relationship between EMDR processing and Rapid Eye Movement (REM).

EMDR and REM

In 1953 the discovery of rapid eye movement (REM) sleep led scientists to understand that there is a mentally active period in which dreaming occurs. Before the 1950s, most scientists thought of sleep as an unchanging, dormant period of little interest. At that time, hardly anything was known about sleep, dreaming, or the brain’s processing of information and memories.
Scientists found that rather than fleeting events, dreams vary in length according to the length of REM period. They then divided non-REM sleep into four stages, accounting for about 75 percent of total sleep. In each stage, brain waves become progressively larger and slower, and sleep becomes deeper. After reaching stage 4, the deepest period, the pattern reverses and sleep becomes progressively lighter until REM sleep, the most active period occurs. This cycle typically occurs about once every 90 minutes in humans.
Scientists also found that brain activity during REM sleep begins in the pons, a structure in the brain stem, and neighboring midbrain regions. The pons sends signals to the thalamus and to the cerebral cortex that is responsible for most thought processes.
More recently it was discovered that REM sleep is linked to our ability to learn and remember. While it is often true that we dream throughout the night, sometimes while in deep sleep, the sleep marked by slow EEG waves, during which the body repairs itself, releasing a growth hormone. The brain cycles through REM sleep about four to six times a night, each time marked by irregular breathing, increased heart rate and brain temperature, general physiological arousal.

Mind Picture

The first REM cycle follows ninety minutes of slow-wave deep sleep and lasts about ten minutes. REM cycles lengthen though the night and the dreams in them get more bizarre and detailed like wacky movies. REM dreams tend to be uniformly more emotional and memorable than non-REM ones. One of the most interesting aspects of REM sleep is that, for its duration, we are paralyzed from the neck down, and our threshold for sensory input is raised, so that external stimuli rarely reach and wake us. At that point, the brain is soaked in acetylcholine, which seems to stimulate nerve cells while it strips muscles of tone and tension. At the same time, serotonin levels plummet.

It is also understood that a narrative structure is forming in the neocortex, our meaning maker, as it creates stories out of the neuronal chaos. These stories are the clues to our inner self. It is interesting to note that when brains are scanned during dreaming, researchers find that the frontal lobes, which integrate information, are shut down, and the brain is driven by the emotional centers processing information through the amygdala, through the hippocampus and into the hypothalamus. The amygdala transforms sensory stimuli into emotional and hormonal signals that control emotional response. The hippocampus creates association to the information being processed and the hypothalamus regulates motivated behavior. The keen relationship between the REM sleep cycles and the information processing mechanisms of the brain suggests this to be the foundation upon which the efficacy of the EMDR protocol sustains itself.

Another way to conceptualize this is to picture the cognitive abilities residing in the left hemisphere of the brain and the emotional content residing in the right hemisphere. When synchronization of the hemispheres is disturbed, thoughts are significantly less integrated with feelings. The athlete becomes a victim of their emotions, without appropriate balancing cognitions. EMDR physiologically accomplishes a rebalancing, which then restores the previous level of performance and fosters enhanced performance in the future. It should be noted that each team and athlete has distinct individual performance requirements. The use of EMDR allows addressing the individual experience, interpretation of that experience, and reprocessing of the information by utilizing the individual athlete's experiences and individual cognitions in order to achieve a more effective outcome.

Personality psychology

Personality psychology is a branch of psychology that studies personality and individual differences. Its areas of focus include.

• Constructing a coherent picture of a person and his or her major psychological processes.
  
• Investigating individual differences, that is, how people can differ from one another.
• Investigating human nature, that is, how all people's behaviour is similar.

Personality can be defined as a dynamic and organized set of characteristics possessed by a person that uniquely influences his or her cognitions, motivations, and behaviors in various situations. The word "personality" originates from the Latin persona, which means mask. Significantly, in the theatre of the ancient Latin-speaking world, the mask was not used as a plot device to disguise the identity of a character, but rather was a convention employed to represent or typify that character.

The pioneering American psychologist, Gordon Allport (1937) described two major ways to study personality, the nomothetic and the ideographic. Nomothetic psychology seeks general laws that can be applied to many different people, such as the principle of self-actualization, or the trait of extraversion. Ideographic psychology is an attempt to understand the unique aspects of a particular individual.

The study of personality has a broad and varied history in psychology, with an abundance of theoretical traditions. The major theories include dispositional (trait) perspective, psychodynamic, humanistic, biological, behaviorist and social learning perspective. There is no consensus on the definition of "personality" in psychology. Most researchers and psychologists do not explicitly identify themselves with a certain perspective and often take an eclectic approach. Some research is empirically driven such as the "Big 5" personality model whereas other research emphasizes theory development such as psychodynamics. There is also a substantial emphasis on the applied field of personality testing. In psychological education and training, the study of the nature of personality and its psychological development is usually reviewed as a prerequisite to courses in abnormal or clinical psychology.

Brain Mapping (QEEG)

Electrical activity created by the heart is recorded as an electrocardiogram (EKG) and electrical activity generated by muscles are recorded as electromyogram (EMG). Electrical activity generated by the brain is measured and recorded as an electroencephalogram (EEG). Over the past 20 years we have witnessed a rapid growth in the use of signal analysis techniques used in a clinical setting to measure brainwave activity. Many times it is referred to as "tomography." Technically, topographical brain mapping refers to the analysis of the distribution of EEG waveforms generated by the brain. A good example of topographic mapping is provided by the colorful daily weather maps shown on television. Average temperature gradation is depicted on a national map based on a mathematical computation. It is similar when converting brainwave activity into a brain map.

Cognitive behavioral psychology has demonstrated that action follows thought. Thought patterns formed in the brain depend upon the energy produced there and how that energy is distributed to different areas of the brain. The specialists at the Center for Cognitive Enhancement employ electroencephalographic (EEG) waveform equipment to focus on brain patterns to aid in determining where to make necessary changes in the patterns that affect a person's attitude, emotion, behavior, and cognitive functioning. This important assessment and diagnostic tool is sometimes referred to as neurofeedback imagery, or topographical brain mapping. Neurofeedback technology records information by frequencies, commonly called hertz (Hz) when mapping the operation of neurotransmitters in the brain. This process is very important in both diagnosis of disorders and for effective neurofeedback training to enhance cognitive activity and personal performance.

Depression And Anxiety

I end up assessing to see whether depression or anxiety is the more. While the precise causes of anxiety. Depression and anxiety is apart of my life. Panic attacks and depression usually go together.

What is the Best Treatment For Curing Panic Attacks and Depression? I need that little dose of Celexa to make it through the day. Researchers examined 1442 twin pairs and found that about one third of those diagnosed with depression or anxiety also had insomnia.

They told me to think about all of the different things in my life that were getting me down at present. Two new studies show that problems with the mind can play a significant role in problems of the heart. This is caused by your body immune.

Just because you have a problem. Millions more suffer from some form of anxiety disorder. Did you know that studies about exercise and depression have been going on for almost two hundred years? It can happen to happy and perfectly normal people of all ages including children.

Circle of Anxiety

Anxiety: In a society where stress is a constant companion anxiety reigns supreme among
disorders. Conservative estimates place its incidence in the population at 25%, with 19%
of men and 31% of women experiencing severe symptoms. Contemporary research on stress
indicates it may be behind a wide variety of physical disorders ranging from hypertension
to irritable bowel syndrome. Anxiety disorders include Panic Attacks, Post Traumatic Stress
Disorder, and Obsessive Compulsive Disorder.

Case Study: The client was a female, middle aged, with a teenage son. She was experiencing
constant anxiety attacks, could not sleep, and was unable to work or function at home.
She was experiencing racing thoughts that were delusional and constantly revolved around
her failure to help her son who has OCD. After performing a biodiagnostic interview and a
QEEG brain map, we had her doctor prescribe her 100mgs of Zoloft and began training her
with neurofeedback and Audio Visual Entrainment (AVE). By session four she had exceeded
her baseline goals in the alpha frequency and experienced a dramatic reduction in symptoms.
By session five her meds were reduced by 50% and she was able to concentrate at work again.
By session eight her meds were reduced 50% again she was sleeping well, and was having
profound insights into the issues that precipitated the panic attacks. By session ten she
was preparing to reduce her meds another 50%, was reporting that she felt relaxed and
happy, and that things were going well at home and work.

Research Available: Anxiety was one of the first disorders treated with neurofeedback by
Joe Kamiya at the University of Chicago back in the 60's. Both state and trait anxiety
have been documented to be reduced by alpha training with neurofeedback. Numerous other
group studies have been conducted with similar results since then and a great number of
case studies as well.

Anxiety

While anxiety has a lot to do with one's thinking and spirituality, it also has to do with
our bodies.

One physical aspect of anxiety involves centers in the brain called basal ganglia. These
centers deal with fear and fine motor skills. When we experience panic or extreme anxiety,
these centers become over-active. We may predict the worst, become shaky and become too
sensitive to body functions. We feel and experience too much. We feel our heart beating.
We are too aware. This is useful if we were in a situation where we need to escape from a
real danger. People who have had a panic attack will do everything they can not to
experience another one. It feels like certain death and loss of control. It is the
over-control that can actually make the condition worse.
Obsessive thinking can also trigger anxiety. These thoughts usually are repetitive and difficult to redirect. In brain imaging we see that when this happens, we see over activity
in the cingulated gyrus. We might worry about our health, germs, or disease. What people
think of us might start to rule our actions. We might experience intrusive thoughts about
hurting someone or ourselves. We then worry about, "why am I thinking these thoughts? Am I
going to lose my mind?" Fear of what people are going to think about us and worry about
losing control is also classic symptoms of anxiety.
It is important to know that people do recover from anxiety. The first step is to find
someone "safe" to share your feelings and what has happened. Sharing with a trust friend
can bring some relief. Sharing with a counselor can bring some good information and tools
to develop a recovery plan. Talking with someone can help us gain perspective and realize
this will pass. It is kind of like a ground wire in electricity--it stops us from
short-circuiting.

About Author:

I collected this data from different books, Internet search. I am very interested in Psychology.
I like Reading different psychology books and other activities. I want share my knowledge to
others In this way I write this blog.
What,s your thoughts about my above post please send me your comments and Thanks for visits.

Social psychology

Q.What is Social Psychology?

Answer> According to psychologist Gordon Allport, social psychology is a discipline that uses scientific methods "to understand and explain how the thought, feeling and behavior of individuals are influenced by the actual, imagined or implied presence of other human beings" (1985).

Brief History of Social Psychology:

While Plato referred to the idea of the "crowd mind" and concepts such as social loafing and social facilitation were introduced in the late-1800s, it wasn't until after World War II that research on social psychology would begin in earnest. The horrors of the Holocaust led researchers to study the effects of social influence, conformity, and obedience.

The U.S. government also became interested in applying social psychological concepts to influencing citizens. Social psychology has continued to grow throughout the twentieth century, inspiring research that has contributed to our understanding of social experience and behavior.

How Is Social Psychology Different From Other Disciplines?

It is important to understand how social psychology differs from other disciplines. Social psychology is often confused with folk wisdom, personality psychology and sociology. What makes social psychology different? Unlike folk wisdom, which relies on anecdotal observations and subjective interpretation, social psychology employs scientific methods and empirical study of social phenomena.

While personality psychology focuses on individual traits, characteristics, and thoughts, social psychology is focused on situations. Social psychologists are interested in the impact that social environment and interaction has on attitudes and behaviors.

Finally, it is important to distinguish between social psychology and sociology. While there are many similarities between the two, sociology tends to looks at social behavior and influences at a very broad-based level. Sociologists are interested in the institutions and culture that influence social psychology. Psychologists instead focus on situational variables that affect social behavior. While psychology and sociology both study similar topics, they are looking at these topics from different perspectives.

Thanks

Momory Definition and Stages

Definition of Memory:

1. The mental faculty of retaining and recalling past experience based on the mental processes of learning, retention, recall, and recognition.

2. the ability to recall events, experiences, information, and skills.

3.The capacity to recall previously experienced sensations, information, data and ideas.

4.Memory refers to the processes that are used to acquire, store, retain and later retrieve information. There are three major processes involved in memory: encoding, storage and retrieval.

Have you ever wondered how you manage to remember information for a test? The ability to create new memories, store them for periods of time, and recall them when they are needed allows us to learn and interact. The study of human memory has been a subject of science and philosophy for thousands of years and has become one of the major topics of interest within cognitive psychology. But what exactly is memory? How are memories formed? The following overview offers a brief look at what memory is, how it works and how it is organized.

Memory refers to the processes that are used to acquire, store, retain and later retrieve information. There are three major processes involved in memory: encoding, storage and retrieval.

The Stage Model of Memory:

While several different models of memory have been proposed, the stage model of memory is often used to explain the basic structure and function of memory. Initially proposed in 1968 by Atkinson and Shiffrin, this theory outlines three separate stages of memory: sensory memory, short-term (working) memory and long-term memory.

• Sensory Memory:

Sensory memory is the earliest stage of memory. During this stage, sensory information from the environment is stored for a very brief period of time, generally for no longer than a half-second for visual information and 3 or 4 seconds for auditory information. We attend to only certain aspects of this sensory memory, allowing some of this information to pass into the next stage - short-term memory.

• Short-Term (Working) Memory:

Short-term memory, also known as working memory, is the information we are currently aware of or thinking about. In Freudian psychology, this memory would be referred to as the conscious mind. Paying attention to sensory memories generates the information in short-term memory. Most of the information stored in working memory will be stored for approximately 20 to 30 seconds. While many of our short-term memories are quickly forgotten, attending to this information allows it to continue on the next stage - long-term memory.

• Long-Term Memory:

Long-term memory refers to the continuing storage of information. In Freudian psychology, long-term memory would be call the preconscious and unconscious. This information is largely outside of our awareness, but can be called into working memory to be used when needed. Some of this information is fairly easy to recall, while other memories are much more difficult to access.

hello ! I am Maqsood Ahmad This data is collected from the different books and online research it not copy on the other way. I hope increase your knowledge due to this my post and Thanks for reading my post. See you later

What is Illusion ?

Illusion

History of the illusion:

As indicated on the displays, the illusion has been developed independently in two laboratories, and was presented by both laboratories at the Society for Neuroscience conference in Washington, D.C., in November 2008.
I developed the effect as an extension of the illusions that Emily Knight, Zhong Lin Lu, and I presented at the May 2008 Best illusion of the year contest (here is a link to the pdf of the entry) and as an extension of our work on “feature blur” in the visual periphery.

Peter Meilstrup and Mike Shadlen presented their version of the illusion as part of a continuation of Shadlen and Movshon’s work on motion signals in the brain (specifically, in area MT of the visual cortex).

Definition of Illusion:

i- According to " Voltaire" Everything's fine today, that is our illusion.
ii- According to "Socrates" A system of morality which is based on relative emotional values is a mere illusion, a thoroughly vulgar conception which has nothing sound in it and nothing true.
iii- According to "Friedrich Nietzsche" Love matches, so called, have illusion for their father and need for their mother.
Thus According to my study "Wrong Perception is called Illusion".

Types of Illusion:

1-Müller-Lyer illusion
2-Poggendorff illusion
3-Nacker cube illusion
4-Hering illusion

1-Müller-Lyer illusion

Müller-Lyer arrows figure 1889. The most famous illusion: the outward-going 'arrow heads' produce expansion of the 'shaft' and the inward-going heads contraction. This was, however, left unexplained, and it is not clear why it should produce size changes without apparent changes of angle.

All these theories had a common feature: they were attempts to explain the distortion in terms of the stimulus pattern without reference to its significance in terms of the perception of objects. There was, however, one quite different suggestion made by A. Thiéry (1896) that the distortions are related to perspective depth features. Thiéry regarded the Müller-Lyer arrows as drawings of such objects as a saw-horse, seen in three dimensions, with the legs going away from the observer in the acute-angled figure and towards him in the obtuse-angled figure. This suggestion has seldom been considered until recently, though the 'perspective theory' was described by R. H. Woodworth in 1938: 'In the Müller-Lyer figure the obliques readily suggest perspective and if this is followed one of the vertical lines appears farther away and therefore objectively longer than the other'. This quotation brings out the immediate difficulties of developing an adequate theory along these lines, for the distortion occurs even when the perspective suggestion is not followed up, for the figure generally appears flat and yet distorted; and there is no hint given of a modus operandi, or brain mechanism responsible for the size changes. An adequate theory following Thiéry's suggestion that perspective is somehow important must show how distortion occurs though the figures appear flat. It should also indicate the kind of brain mechanisms responsible.

2-Poggendorff illusion

The Poggendorff illusion figure (1860). The straight line crossing the rectangle appears displaced.

3-Nacker cube illusion

FIG.(a) Necker cube. This is the most famous of many depth-ambiguous, figures. (When presented with no background it changes in shape with each reversal, the apparent back being larger than the apparent front face.) (b) Necker rhomboid. This is the original form, presented by L. A. Necker in 1832. The types of illusions which concern us here are, however, entirely different from either optical or sensory illusions. We may call these perceptual illusions. They arise from misinterpretation by the brain of sensory information. Several perceptual illusions were known to the ancient Greeks, but they have only been studied experimentally for just over a century. The first scientific description in modern times was a letter by a Swiss naturalist, L. A. Necker, to Sir David Brewster (Necker, 1832) describing how a rhomboid reverses in depth, sometimes one face appearing the nearer, sometimes another. Necker correctly noted that changes of eye fixation could induce this change in perception, but that it would occur quite spontaneously. This famous effect is generally illustrated with an isometric skeleton cube ( a) rather than Necker's original figure Perceptual reversals, or alternations (there can be several alternative perceptions) are not limited to vision. Repeated words, presented on an endless tape loop, give analogous auditory reversals (Warren and Gregory 1958 [REF 3]); A similar, even more striking effect, was noted by W. J. Sinsteden: that the rotating vanes of a windmill spontaneously reverse direction when it is not clear whether one is seeing the front or the back of the windmill (for references, see Boring, 1942). This effect is well shown by casting the shadow of a slowly rotating vane upon a screen, thus removing all information of which is the back and which the front. The shadow will also at times appear to expand and contract upon the plane of the screen. It is important to note that these effects are not perceptual distortions of the retinal image: they are alternative interpretations of the image, in terms of possible objects, and only one interpretation is correct.

4-Hering illusion

FIG. (a) Hering illusion (1861) The straight parallel lines appear bowed outwards. (b) Wundt's variant of the Hering illusion: the parallel lines appear bowed inwards (1896). Interest in the illusions became general upon the publication of several figures showing distortions which could produce errors in using optical instruments. This concerned physicists and astronomers a hundred years ago, when photographic and other ways of avoiding visual errors were not available. The first of the special distortion figures was the Poggendorff figure of 1860 . This was followed by the Hering illusion (1861); its converse being devised by Wundt much later, in 1896. The most famous illusion of all is the Müller-Lyer arrow figure. This was devised by F. C. Müller-Lyer and was first presented in fifteen variants (Müller-Lyer, 1889). This figure is so simple, and the distortion so compelling that it was immediately accepted as the primary target for theory and experiment. All sorts of theories were advanced: Wundt's eye movement theory (in spite of its inadequacy); that the 'wings' of the arrow heads drew attention away from the ends of the central line, or 'arrow shaft', to make it expand or contract; that the heads induced a state of empathy in the observer (though the distortion seems far too constant for such an explanation), that the distortion is a special case of a supposed general principle that acute angles tend to be overestimated and obtuse angles underestimated.

What is Perception ?

It’s All About Perception

Definition of Perception:

Very simple definition of Perception is
Sensation + Meaning = Perception

"Give meaning of any things through his sensation is called Perception".

"Thus perception in humans describes the process whereby sensory stimulation is translated into organized experience."

Types of Perception:
1- Form perception.
2- Color perception.
3- Perception of Movement.
4- Time Perception.
5- Perception of Space and Depth.

There are many different ways of perceiving the world. One of these ways is by perceptual organization. Perceptual organization are processes used to group basic sensory elements together into perceivable objects. The two basic principles of perceptual organization involves perceiving figures embedded in a perceptual background and organizing what you see, or what you perceive, in the simplest form possible. Another type of perception is depth perception, which is primarily utilized by visual or auditory senses. The organ used for visual perception is the eye. The eye is an extremely complex organ. It is composed of multiple of structures each having it's own specific function or functions (refer to diagram). The cornea is a clear protective membrane which allows for the passage of light but blocks the entrance of dust. The lens is just behind the cornea and it focuses the light entering into the eye. The light forms an image which falls on the retina. This image is upside down and is processed by the brain. The amount of light entering the eye is controlled by the iris, the colored structure of the eye. The pupil is a black dot in the center of the eye through which light passes. The retina contains over 100 million nerve cells known as rods and cones. Cones are responsible for colored vision and rods are used for black and white vision.

1-Figure Ground Perception:

Suppose ! You can see the figure of rabbit and tree. If you see the tree then rabbit go to the ground and tree called the figure. Suppose that if you see the rabbit then tree go to ground and rabbit called the figure. I hope you understand.

Figure ground perception is the tendency to discriminate between target and background stimuli. The stimulus we perceive as being the target is referred to as the figure. The other stimuli that we do not perceive as the target make up the background, or ground.
The vase seen at right can be perceived in two different ways. If the black is perceived as the background, you will see a vase. However, if you perceive the vase as the background, you will see two faces.

An interesting phenomenon occurs when looking at a square centered over top of several, closely spaced concentric circles. In the figure at left, all of the sides of the square are perfectly straight. Go ahead and check with a straight edge. However, the sides of the square will appear to bend inward toward the center of the circles. This is known as background mediated illusion. The background is responsible for the distortion seen in the figure.

Organization of Perception

The Law of Pragnanz, also known as the Law of Simplicity, states that we tend to perceive the world in the simplest form possible. There are two major parts to this law: closure and grouping. Closure is the tendency to fill in missing portions from a perceptual array, or to fill in the gaps. Grouping occurs when similar or proximal stimuli are perceived as belonging together in a group.

A common example used to illustrate closure is the perception of a complete triangle from three lines. This can be obseved at right. If you look closely you can actually see two triangles in the figure. Grouping can be observed by looking at the collection of black dots below. Your brain groups the dots together.

Depth Perception

Humans perceive depth in a seemingly two dimensional world by interpreting binocular visual cues from the environment. They interpret those stimuli in the brain. Two depth cues that require both eyes are binocular disparity and convergence. Your eyes are separated by a space. This allows them to receive two slightly different images. As distance from your eyes increases the difference between the two images decreases. Binocular disparity is the depth cue that is based on the difference between these two images. Your brain interprets images that are very similar in both eyes as far away, and images that are different in both eyes as closer.

Another way for you brain to interpret the distance to objects is known as convergence. This is when your brain interprets the tension in the muscles that control eye movement. Binocular disparity is used with images that are farther away, perhaps up to 1000 feet. Convergence is used when the object is eighty feet away or closer.

An artistic use of the human processing of depth perception is utilized in stereograms. Have you ever looked at a stereoscopic image, or "magic eye"? They are two dimensional images, but they can be perceived as three dimensional images in brain. The feeling of "depth" that you get by looking at a statue instead of looking at a photo of the same statue, is due to the fact that the human body has two eyes. By having two pictures of the same object, taken by two different positions, which is the case of the human eyes, you can get a "three dimensional image." In the same way, the eyes forward to the brain two slightly different pictures. It is the brain that must "compute" a 3-D representation of the scene. The brain can make mistakes in this process of designation of pairs! It is these mistakes which make possible the 3-D feeling that we get from viewing a stereogram.
To see some examples of stereograms follow any of the links below.

Size Constancy

Imagine yourself outside looking up at an airplane high in the sky. You lift up your hand and see that the plane is smaller than your finger, yet you still know that the plane is large enough to hold hundreds of people. Due to the information in your memory stores, you are still able to perceive the actual size of the airplane despite a change in the size of the retinal image. This concept is known as size constancy.
Despite the fact that you know images that are far away are actually the same size as if they were closer, your brain can be fooled. An example of this is the moon illusion, in which the moon on the horizon appears larger than one higher in the sky. The moon doesn't actually changes size, but it's relationship to the horizon can make it seem larger lower in the sky. This phenomenon can also be explained using the figure below. The center circles are actually both the same size, yet they appear to different because of their relationship to the surrounding circles. Our brain perceives the circle surrounded by larger circles as smaller, because it is smaller in relation to the surrounding circles. The opposite is true for the circle surrounded by smaller circles.

I hope you like my blog which about Perception. I hope you enjoy it.