Processing Speed

Types of Processing Speed

Processing speed is not a one-dimensional construct. As already indicated, processing speed can be observed in visual processing, verbal processing, or motor skills. Problems in one or more of these areas can manifest in problems with academic difficulties or general day-to-day difficulties. It is rare to be slow at all of these issues, but most individuals with processing speed deficits have difficulties in more than one area.

Visual processing relates to how well one’s eyes perceive information and relay it to the brain. In its simplest form, visual processing can be measured by how quickly the eyes dilate to light or how quickly an individual responds to a visual stimulus. It is related to almost everything an individual does. Research has indicated that drivers with slower visual processing have slower visual reaction times and get into more accidents. Studies have shown that individuals with slower visual processing have difficulties with tasks such as looking up phone numbers, reading directions, counting out change, and finding an item on a crowded store shelf.

Verbal processing relates to how quickly an individual hears a stimulus and reacts to it. “Reacting” may include a simple response such as a change in a facial expression or more complex processing such as making sense of what someone has said and providing a cogent response. Verbal processing also relates to the ability to find the “right word” when conversing or writing. People with slower verbal processing may appear to have difficulty in fast-paced verbal environments. Research has shown that problems with verbal processing speed are related to problems with nearly all aspects of verbal memory and comprehending instructions.

Motor speed, as it relates to the field of “processing speed,” generally relates to fine motor [Page 1317]agility, such as how fast an individual can copy something (visual and motor speed), read paragraphs (visual, verbal, and motor speed), or put pegs in a board (motor speed, although vision does play a role), rather than how fast someone can run.

Biology of Processing Speed

No single brain region has (or is likely ever to be) identified as the problem with processing speed. As with most higher order brain functions, one’s ability in processing speed involves a complex network of different parts of the brain, all acting in concert. Differences in speed of processing cannot, at this time, be “mapped” onto different areas of the brain. Instead, it is thought to be a “global” concept that affects the way the entire brain processes information. Differences in speed of processing may be most related to how well the brain is “wired”–for example, the size of the nerves in the brain, how well the brain metabolizes glucose, which is also known as the brain’s “fuel,” and the integrity of how rapidly and efficiently the brain cells “fire.” Each of these components has been shown to affect processing speed, but none alone explains the cause of processing speed problems.

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