Sequence Learning - History

History

In the first half of the 20th century, Margaret Floy Washburn, John B. Watson, and other behaviorists believed behavioral sequencing to be governed by the reflex chain, which states that stimulation caused by an initial movement triggers an additional movement, which triggers another additional movement, and so on. In 1951, Karl Lashley, a neurophysiologist at Harvard University, published “The Problem of Serial Order in Behavior,” addressing the current beliefs about sequence learning and introducing his hypothesis. He criticized the previous view on the basis of six lines of evidence:

The first line is that movements can occur even when sensory feedback is interrupted. The second is that some movement sequences occur too quickly for elements of the sequences to be triggered by feedback from the preceding elements. Next is that the errors in behavior suggest internal plans for what will be done later. Also the time to initiate a movement sequence can increase with the length or complexity of the sequence. The next line is the properties of movements occurring early in a sequence can anticipate later features. Then lastly the neural activity can indicate preparation of upcoming behavior events, including upcoming behavior events in the relatively long-term future.

Lashley argued that sequence learning, or behavioral sequencing or serial order in behavior, is not attributable to sensory feedback. Rather, he proposed that there are plans for behavior since the nervous system prepares for some behaviors but not others. He said that there was a hierarchical organization of plans. He came up with several lines of evidence. The first of these is that the context changes functional interpretations of the same behaviors, such as the way “wright, right, right, rite, and write” are interpreted based on the context of the sentence. “Right” can be interpreted as a direction or as something good depending on the context. A second line of evidence says that errors are involved in human behavior as hierarchical organization. In addition, “hierarchical organization of plans comes from the timing of behavioral sequences.” The larger the phrase, the longer the response time, which factors into “decoding” or “unpacking” hierarchical plans. Additional evidence is how easy or hard it is to learn a sequence. The mind can create a “memory for what is about to happen” as well as a “memory for what has happened.” The final evidence for the hierarchical organization of plans is characterized by "chunking". This skill combines multiple units into larger units.