BOTTOM UP IS EXTENTIONAL ORIENTATION, GUIDED BY AN OBJECT
TOP DOWN IS VERBAL WORLD
BOTTOM UP IS EXTENTIONAL WORLD
A top-down approach (also known as stepwise design or deductive reasoning,[1] and in many cases used as a synonym of analysis or decomposition) is essentially the breaking down of a system to gain insight into its compositional sub-systems. In a top-down approach an overview of the system is formulated, specifying but not detailing any first-level subsystems. Each subsystem is then refined in yet greater detail, sometimes in many additional subsystem levels, until the entire specification is reduced to base elements. A top-down model is often specified with the assistance of "black boxes", these make it easier to manipulate. However, black boxes may fail to elucidate elementary mechanisms or be detailed enough to realistically validate the model. Top down approach starts with the big picture. It breaks down from there into smaller segments.[2]
A bottom-up approach (also known as inductive reasoning,[1] and in many cases used as a synonym of synthesis) is the piecing together of systems to give rise to grander systems, thus making the original systems sub-systems of the emergent system. Bottom-up processing is a type of information processing based on incoming data from the environment to form a perception. Information enters the eyes in one direction (input), and is then turned into an image by the brain that can be interpreted and recognized as a perception (output). In a bottom-up approach the individual base elements of the system are first specified in great detail. These elements are then linked together to form larger subsystems, which then in turn are linked, sometimes in many levels, until a complete top-level system is formed. This strategy often resembles a "seed" model, whereby the beginnings are small but eventually grow in complexity and completeness. However, "organic strategies" may result in a tangle of elements and subsystems, developed in isolation and subject to local optimization as opposed to meeting a global purpose.
VISUAL:
TOP
ENVIRONMENT
OBJECT
FEATURES
LIGHTS
BOTTOM
Top-Down and Bottom-Up Processing
When an interpretation emerges from the data, this is called data-driven or bottom-up
processing. Perception must be largely data-driven because it must
accurately reflect events in the outside world. You want the
interpretation of a scene to be determined mostly by information from
the senses, not by your expectations.
What is data-driven or bottom-up processing? What is schema-driven or top-down processing?
In many situations, however, your knowledge or expectations will influence perception. This is called schema-driven or top-down processing. A schema is a pattern formed earlier in your experience.
Larger scale or more abstract concepts are referred to
as higher level, while concrete details (such as the input from the
senses) are referred to as lower level. Top-down processing occurs any
time a higher-level concept influences your interpretation of lower level sensory data.
What is set or expectancy?
Top-down processing is shown by the phenomena of set or expectancy. A classic example is the Rat Man of Bugelski and Alampay (1961).
The "Rat-Man" picture
Subjects saw this picture after viewing earlier slides that showed line drawings of (1) animals, or (2) faces.
Depending on whether they saw animals or faces in previous slides,
subjects reported seeing either (1) a rat or (2) a man wearing glasses.
They had been "set" for one or the other interpretation by the preceding
slides. This is a form of top-down processing, in which a schema
influences interpretation of the data.
In what respect do cartoons rely upon top-down processing?
Comics and cartoons provide many examples of top-down
processing. Simple cues are used to suggest complex feelings and
emotions. Cartoonists have a set of conventions for conveying
information about mental and physical states. Tiny popping bubbles, for
example, show drunkenness. Movement is shown by lines and little puffs
of dust trailing after shoes. Spoken language is shown inside a bubble
made out of a continuous line. A silent thought is shown inside a broken
line. A sudden idea may be shown as a lightbulb lighting up over a
character's head. Beads of sweat flying off a character show anxiety or
physical exertion. After one gains some experience reading comics, these
cues are processed automatically; one is hardly aware of them.
In what sense do we go "beyond the information given"?
In general, top-down processing—information processing based on previous knowledge or schemata—allows us to make inferences: to "perceive" or "know" more than is contained in the data. Little cartoon droplets do not
contain the information that a character is working hard. We add that
information based upon our previous experience and knowledge of the
conventions of cartooning.
Jerome Bruner titled a book about cognitive development Beyond the Information Given
(1972) He was acknowledging the pivotal role of inference in cognition.
We go "beyond the information given" constantly in our mental
processes. We learn to add assumptions and supplemental information
derived from past experience to the evidence of our senses, and that is
how we make sense of our world.
IN PSYCHOLOGY
hese terms are also employed in neuroscience, cognitive neuroscience and cognitive psychology to discuss the flow of information in processing.[5] Typically sensory input is considered "down", and higher cognitive processes, which have more information from other sources, are considered "up". A bottom-up process is characterized by an absence of higher level direction in sensory processing, whereas a top-down process is characterized by a high level of direction of sensory processing by more cognition, such as goals or targets (Beiderman, 19).[4]
According to Psychology notes written by Dr. Charles Ramskov, a Psychology professor at De Anza College, Rock, Neiser, and Gregory claim that top-down approach involves perception that is an active and constructive process.[6] Additionally, it is an approach not directly given by stimulus input, but is the result of stimulus, internal hypotheses, and expectation interactions. According to Theoretical Synthesis, "when a stimulus is presented short and clarity is uncertain that gives a vague stimulus, perception becomes a top-down approach."[7]
Conversely, Psychology defines bottom-up processing as an approach wherein there is a progression from the individual elements to the whole. According to Ramskov, one proponent of bottom-up approach, Gibson, claims that it is a process that includes visual perception that needs information available from proximal stimulus produced by the distal stimulus.[8] Theoretical Synthesis also claims that bottom-up processing occurs "when a stimulus is presented long and clearly enough."[7]
Cognitively speaking, certain cognitive processes, such as fast reactions or quick visual identification, are considered bottom-up processes because they rely primarily on sensory information, whereas processes such as motor control and directed attention are considered top-down because they are goal directed. Neurologically speaking, some areas of the brain, such as area V1 mostly have bottom-up connections.[7] Other areas, such as the fusiform gyrus have inputs from higher brain areas and are considered to have top-down influence.[9]
The study of visual attention provides an example. If your attention is drawn to a flower in a field, it may be because the color or shape of the flower are visually salient. The information that caused you to attend to the flower came to you in a bottom-up fashion—your attention was not contingent upon knowledge of the flower; the outside stimulus was sufficient on its own. Contrast this situation with one in which you are looking for a flower. You have a representation of what you are looking for. When you see the object you are looking for, it is salient. This is an example of the use of top-down information.
In cognitive terms, two thinking approaches are distinguished. "Top-down" (or "big chunk") is stereotypically the visionary, or the person who sees the larger picture and overview. Such people focus on the big picture and from that derive the details to support it. "Bottom-up" (or "small chunk") cognition is akin to focusing on the detail primarily, rather than the landscape. The expression "seeing the wood for the trees" references the two styles of cognition.
IN PSYCHOLOGY
hese terms are also employed in neuroscience, cognitive neuroscience and cognitive psychology to discuss the flow of information in processing.[5] Typically sensory input is considered "down", and higher cognitive processes, which have more information from other sources, are considered "up". A bottom-up process is characterized by an absence of higher level direction in sensory processing, whereas a top-down process is characterized by a high level of direction of sensory processing by more cognition, such as goals or targets (Beiderman, 19).[4]
According to Psychology notes written by Dr. Charles Ramskov, a Psychology professor at De Anza College, Rock, Neiser, and Gregory claim that top-down approach involves perception that is an active and constructive process.[6] Additionally, it is an approach not directly given by stimulus input, but is the result of stimulus, internal hypotheses, and expectation interactions. According to Theoretical Synthesis, "when a stimulus is presented short and clarity is uncertain that gives a vague stimulus, perception becomes a top-down approach."[7]
Conversely, Psychology defines bottom-up processing as an approach wherein there is a progression from the individual elements to the whole. According to Ramskov, one proponent of bottom-up approach, Gibson, claims that it is a process that includes visual perception that needs information available from proximal stimulus produced by the distal stimulus.[8] Theoretical Synthesis also claims that bottom-up processing occurs "when a stimulus is presented long and clearly enough."[7]
Cognitively speaking, certain cognitive processes, such as fast reactions or quick visual identification, are considered bottom-up processes because they rely primarily on sensory information, whereas processes such as motor control and directed attention are considered top-down because they are goal directed. Neurologically speaking, some areas of the brain, such as area V1 mostly have bottom-up connections.[7] Other areas, such as the fusiform gyrus have inputs from higher brain areas and are considered to have top-down influence.[9]
The study of visual attention provides an example. If your attention is drawn to a flower in a field, it may be because the color or shape of the flower are visually salient. The information that caused you to attend to the flower came to you in a bottom-up fashion—your attention was not contingent upon knowledge of the flower; the outside stimulus was sufficient on its own. Contrast this situation with one in which you are looking for a flower. You have a representation of what you are looking for. When you see the object you are looking for, it is salient. This is an example of the use of top-down information.
In cognitive terms, two thinking approaches are distinguished. "Top-down" (or "big chunk") is stereotypically the visionary, or the person who sees the larger picture and overview. Such people focus on the big picture and from that derive the details to support it. "Bottom-up" (or "small chunk") cognition is akin to focusing on the detail primarily, rather than the landscape. The expression "seeing the wood for the trees" references the two styles of cognition.
AUTISM PERCEIVE FROM BOTTOM UP. PERCEPTION OCCUR WHEN TOP HIGHER CONCEPT INTERPRET BOTTOM/LOW SENSORY DATA. AUTISM RECEIVE LOW SENSORY DATA WITHOUT INTERPRETATION OF HIGHER CONCEPTS.
SCHIZOPHRENIA IS ON THE OTHER HAND IS A TOP HIGHER CONCEPT WITHOUT LOW SENSORY DATA. THEY HALLUCINATE.
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