by Karen Pryor
The limited hold is scientific terminology—laboratory slang, really—for a good way to use the marker and reinforcer to speed up response to a cue. We’re all used to sluggish responses. You call folks for supper, and in due course, they come; meanwhile the soufflé falls or the soup gets cold. You ask the class members to be quiet, and some sit down and shut up, but it’s quite a while before the last few stop talking. You call your dog to come in the house and it comes, grudgingly, finding half a dozen new things to sniff at before actually reaching the back door.
Suppose you are dealing with just such a behavior. You give the cue, and you get the response, but after a delay. Now you want to fix that. First, practice it a few times to judge the average length of the delay. You can count seconds to yourself, or actually use a stopwatch. Now give the cue, watch the time go by, and reinforce the response if it occurs within the average time. If the cue response occurs outside the time limit, call an end to the trial (with dogs, easily done by moving to a new location). Then give the cue again and start your countdown again.
In Don’t Shoot the Dog I told this story about a limited hold. At Sea Life Park in the 1960s, one of our most effective show highlights was a group of six little spinner dolphins that did various leaps and whirls in response to underwater sound cues. The most spectacular behavior was the aerial spin for which they are named. Initially, when that cue went on, spins occurred raggedly and sporadically across a fifteen-second period. Using a stopwatch, we started turning the cue on only for twelve seconds, and marking and rewarding only spins that occurred during that time. When most of the animals were spinning within that period we cranked down the limited hold, shortening the time to! ten sec onds, then five, and eventually to two and a half seconds. It couldn’t go much shorter, because the animals had to dive, first, to get up speed to jump fast enough to do a good spin. In any case, every animal learned that in order to get a fish it had to hit the air and perform the spin within two and a half seconds of the time the cue went on.
As a result, the animals poised themselves attentively near the underwater loudspeaker. When the spin cue went on, the pool erupted in an explosion of whirling bodies in the air; it was quite spectacular. One day while sitting among the audience I was amused to overhear a professorial type firmly informing his companions that the only way we could be getting that kind of response was by electric shock.
“The object is not to punish slower runs, but to pay for faster ones. You make you criterion roomy enough so that most, but not all, of the runs are within your chosen limit.”
The length of time your learner takes to respond to a cue is called, in the lab, “latency.” A long gap is called high latency, a quick response shows low latency. You can sometimes shape a low latency response, without bothering to measure the time, by asking for a lot of responses in quick succession and reinforcing only the quicker ones. For example, in demonstrating a shift in latency, I sometimes seek out a dog with a slow, lethargic sit: on cue, but high latency. I call him, back up a step or two (to get him moving forward), click and treat when he comes, and repeat a couple of times. When the dog is coming with me willingly I back up and say “sit,” stop, and click just as his back legs begin to fold; treat, call him, back up again quickly, and cue “sit” again, clicking the act of sitting, not waiting for the full sit. Then I progress to backing up, cueing the sit, and clicking as the rump hits the ground; and then to clicking as he sits but only if he sits instantly when he hears the word. If he hesitates, I back up again, ! call him again, and say “sit” again. In about twenty clicks (and thirty seconds or so) the limited hold is down to practically zero and the dog is sitting like a champion. One would then repeat this facing the other direction, and then perhaps in another room, on another day, and finally outdoors, to generalize the low-latency response. And of course having embarked on this repair job you would also drop from your own repertoire the habit of reinforcing slow sits.
PART 2 – NEXT MONTH – HOW TO GET A FAST “COME”
With Kind Permission from Karen Pryor: Many more wonderful articles can be found at www.clickertraining.com