Reading is a complex process and as with most other cognitive processes there are generally two approaches considered when trying to understand it. A bottom-up process occurs when an individual takes the stimuli from the external environment, in this case letters and words, and attempts to process that information without referencing stored or higher -- level knowledge. A top-down process is guided by the person's prior knowledge and expectations. During top-down reading strategies whole words and phrases are comprehended based on prior experience. Reading has been proposed to be a procedure that uses both top-down and bottom-up processing in concert in order to extract meaning from the stimuli.
When an individual is reading a new or unfamiliar article there will still be quite a few familiar words. For instance, conjunctions such is "and" and familiar words such as "cat" will be recognized as whole words with specific meanings by the reader and the comprehension of these words will follow top-down process. For instance when the experienced reader comes across the word "and" in a sentence the reader automatically understands that the two phrases appearing prior to and following this conjunction are connected in some way and experienced readers understand the implicit meaning of the word "and." This process of reading is the classic whole word approach...
Thus, even when reading unfamiliar material, part of the process will contain top-down strategies to make sense of the material and to comprehend the message. Readers will form hypotheses about words and phrases that they encounter and will test hypotheses regarding the relationships and meanings of these phrases based on previous knowledge. This top-down process will help the reader to get a gestalt of the material.
However, in reading new or unfamiliar material there may also be words and combinations of words that are unfamiliar to the individual. When the reader encounters a word like "microcephalic" for the first time the reader will typically break up the word into a pattern of segments (e.g., "mi -- cro -- ce -- pha-lic") and then attempt to combine the segments in order to form a mental representation of the word. Moreover, combinations of words or phrases that are unfamiliar to the individual will be broken down in the similar bottom-up fashion and then combined to extract meaning. For an individual who may be reading text in a different language for the first time this process could be very slow and broken initially until specific words or phrases can become recognized as whole words…
