Cybernetic Cynthia by L.C. Galitz, in Radio Constructor (1970). Cynthia models adaptation to a repeated stimulus. "Cynthia is an electronic 'snail'. Like her biological equivalents, she is a nervous creature. Touch the top of her shell and her head will pop in. A few seconds later her head will pop out again, thinking that the 'danger' has gone. If you do the same again, she will put her head in again and, as before, after she thinks the danger has gone, she will pop her head back out once more. She will do this for about six times, depending on the duration of the tactile stimulus, and the interval between stimuli. Eventually, however, on touching the top of her shell, her head will stay put. Her reasoning' tells her that something or somebody has touched the top of her shell several times; yet, there has been no danger associated with it, i.e. she hasn't been hurt. Therefore, the something or somebody must be friendly. Hence, she needn't waste 'muscular' energy putting her head in (to save it from damage were the originator of the stimulus dangerous), so she keeps it out. Being an animal of short memory, if you leave her for about half a minute, she will have forgotten about you and, on receiving a tactile stimulus, she will repeat the action of putting her head in, waiting a few seconds, and then putting it out again. However, she will not have forgotten completely and, this time round, it will take her less time to learn that you are friendly." – Cybernetic Cynthia, The Radio Constructor, June July 1970.
