What are practice effects?
From PsychWiki - A Collaborative Psychology Wiki
Practice effects are considered a common subtype of order effects. Practice effects can be defined as influences on performance that arises from a practicing a task (Heiman, 2002). Even after practice trials are performed in/for a study, participants have a tendency to perform initial trials poorly because they are still not warmed up to it (Heiman, 2002). Performance can, however, improve after more trials are conducted because this allows participants to become more accurate and a lot quicker. Participants' performance may decrease again, however, because they do have a tendency to become bored and/or fatigued after a while.
Example / Application
Example: [Providing Practice Questions]
Application: A researcher providing practice questions before presenting the questions of concentration, it allows the participants to warm up to the format of the questions administered and to habituate their content. They would be able to do so without contaminating the data (Heiman, 2002).
Heiman, G. W., (2002). Research Methods in Psychology. 3rd Edition. Boston & New York. Houghton Mifflin Company.