Question

Describe the problem of serial order, described by Karl Lashley.

Answer 1

Lashley famous paper called “The Problem of Serial Order in Behavior,” in which he pointed out that complex sequential behavior could not be executed by one response sending a proprioceptive signal back to the brain which would then trigger the next response in the sequence – Behavior had to be controlled by a central, hierarchically organized program. This insight has guided the study of motor behavior, and influenced Noam Chomsky’s critique of Skinner’s theory of language & the development of Chomsky’s theory of generative grammar. Lashley was a pioneer of neuroscience before the term existed, & seeking to understand the connection between the physical structures of the brain & psychological processes of learning, memory, and planning. He eschewed the theoretical perspectives of his time in an attempt to avoid being hampered by a priori assumptions

. Lashley made several fundamental discoveries about how the brain stores & processes information. By implanting insulating chips of mica in rats’ cortexes & showing they had a little effects on learning & behavior, he established that,the cortex processed information in the pattern of activity & connectivity among neurons, . By stating that lesions that undercut slabs of cortex had far more severe consequences lesions that were perpendicular to the cortex, he showe that the principal circuits of the cortex ran up and down into the white matter rather than side-to-side across the cortical surface. His famously unsuccessful search for the “engram” – the localized trace of the memory for a maze in a trained rat’s brain – brought him to propose the principle of "mass action," in which learning is distributed across all parts of the brain rather than stored in a single regions, with the degree of impairment proportional to the amount of brain that was damaged. His complementary principle of "equipotentially" stated that in the event of damage to one area of the brain, other parts of the brain can sometimes assume the role of the damaged region. The principle that memories are not localized to a single spot in the brain is now well accepted.

The problems of serial order in behavior : Lashley's Kegacy :Karl Lashley stated several sources of evidence for the hierarchical organization for behavioral plans, & afterward provided more evidence for this hypothesis. We briefly review that evidence here & then shift from a focus on the structure of plans to the processes by which plans are formed in real time. Two principles emerge from the studies . One is that plans are not formed from scratch for each successive movement sequence but are formed by making changes that are needed to distinguish the movement sequence to be performed & next , the movement sequence that has just been performed. This plan-modification view is supported by two phenomena that discoverd: the parameter remapping effect, & the hand path priming effect. The other principle states that even single movements appear to be controlled with hierarchically organized plans. At the top level are the starting and goal postures. & at the lower level are the intermediate states comprising the transition from the starting posture to the goal posture. The latter principle is supported by another phenomenon discovered , The end-state comfort effect, and by a computational model of motor planning which accounts for a large number of motor phenomena. , the computational model hearkens back to a classical method of generating cartoon animations that relies on the production of key frames first and the production of interframes second.