16/15 ADAPTATION IN THE MULTISTABLE SYSTEM 



Robinson made subjects learn four-figure numbers, perform a 

 second task, and then attempt to recall the numbers; he found 

 that maximal interference occurred when the second task consisted 

 of learning more four-figure numbers. Similarly Skaggs found 

 that after learning five-men positions on the chessboard, the 

 maximal failure of memory was caused by learning other such 

 arrangements. The multistable system's tendency to be dis- 

 organised by new reactions is thus matched by a similar tendency 

 in the nervous system. 



16/15. It should be noticed that the demands that a brain 

 model should show both retroactive inhibition and the ability 

 to accumulate adaptations are opposed; for retroactive inhibition 

 demands that later adaptations shall be destructive to earlier 

 adaptations, while the power to accumulate adaptations demands 

 that the later shall not be destructive to the earlier. The Homeo- 

 stat showed retroactive inhibition at maximal intensity (S. 10/5), 

 for any later adaptation destroyed the earlier totally. A set of 

 iterated systems, with some suitable gating-mechanism, shows 

 the maximal power of accumulating adaptations. A multistable 

 system of some intermediate degree can show both features 

 partially, and will thus resemble the living organism. 



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