of a specific shape and then he would switch the shape. He found that the prior information did not help the subjects; instead it impeded their learning.

One explanation of why transfer does not occur often involves surface structure and deep structure. The surface structure is the way a problem is framed. The deep structure is the steps for the solution. For example, when a math story problem changes contexts from asking how much it costs to reseed a lawn to how much it costs to varnish a table, they