The phenomenon is interference. In this case, because old information is interfering with new, it is called proactive interference. Not it can be stored in memory as the same part with a revision rather than a whole new part. If an operator must make decisions under time constraints, prior experience or practice at the given task will allow the operator to perform at a higher performance level than he or she would without practice. This phenomenon occurs due to increased compatibility between stimulus and response.
Compatibility refers to a learned relationship.
That is, the operator s mental model or schema for the particular task closely resembles the actual task itself. Thus, processing becomes easier under conditions of high compatibility. This could be good if the operator is required to do the same task over and over. For example, if an operator must constantly perform calculations on a TI calculator, then a great deal of practice on a TI machine will improve performance. Effects of practice could be determined if the operator must continually switch back and forth between similar tasks.