"peak shift effect" is a phrase in psychology of education. I want to know the literal meaning of it. Does it mean "effect caused by shifting peaks" or "effect caused by shifts that are at their peak"? I think the former is OK. Am I right?


Suppose you’re training a rat to recognize the difference between a square and a rectangle. You present him a square and a rectangle with a switch in front of each. Every time the rat pushes the rectangle switch, you reward him with a piece of cheese. It won’t take long before the rat chooses the rectangle in every single trial.

Now give the rat a choice between the original rectangle and a longer, skinnier rectangle. The rat will strongly prefer the longer, skinnier rectangle. The rat has been trained to do more than pick out one particular rectangle – it has been trained to be rewarded by the concept of “rectangularness” itself. So when it gets something that’s REALLY rectangular – a very long and skinny rectangle – it strongly prefers it. This is the peak shift effect – it occurs when the strength of a particular response is directly proportional to the magnitude of a somewhat simple perceptual cue. Exaggerate that cue, and you can exaggerate the response it elicits.


  • "Peak shift", in statistics, is the movement of the "peak" of a frequency graph one direction or another due to some change in parameters. – Hot Licks Dec 6 '15 at 12:37

Based on one of the articles cited below the reference you linked to, "peak shift effect" refers to one's increased response to the exaggeration of a visual (or other type of) cue, not "effect caused by shifting peaks" or "effect caused by shifts that are at their peak."

Extrapolating from the rat example, if you are teaching first-graders to name squares and rectangles, for instance, the peak shift effect suggests that they will grasp the concept of "rectangle" more quickly and strongly if you offer them at least one extreme example of a rectangle as part of your demonstration.

Draw two squares on the blackboard; ask if they are the same. Then erase one square and replace it with a slightly horizontally elongated rectangle while naming it. Do all the children see the difference? Erase everything and draw a square again as well as a vertically oriented rectangle. Are they all still able to perceive and correctly name the difference? If not, then draw a square and a greatly elongated rectangle. The peak shift effect predicts that their comprehension of "rectangle" will instantly increase.

If you haven't already read the "Scientific American" article that was cited, here again is the link: http://www.scientificamerican.com/article/carried-to-extremes/

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    Yes, I know what it is about. I just want to know if it means "the shift of peak" or "the peak of shift" to you, when you say "peak shift"? – user127733 Dec 7 '15 at 16:32
  • Building on Hot Licks's comment regarding its use in statistics, it would mean the "shift of the peak" on a graph in the direction that indicates either the students' improved comprehension of the concept or the time it took them to grasp it. I wish I knew more about the subject so I could give you a better answer. I do have some professional editing experience in Educational Psychology, but I had never encountered "the peak shift effect" before you asked your question. I'm sorry. If anyone reading this knows more, please correct me if I am mistaken! – Mark Hubbard Dec 7 '15 at 16:54

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