If two labs both say they are studying memory, how do you know they measured the same thing?
You read the procedure. A construct such as memory is a hypothesized attribute, not something you can place on a desk. The last article treated that point. What this article adds is the operational definition: the operations used to measure or manipulate the construct, written specifically enough that another investigator could carry them out (Cozby & Bates, 2020).
What has to be written so a second investigator can run that procedure?
The steps, the scoring, and the situation. One lab operationalizes memory as free recall after sleep: after eight hours of sleep, people write every name they retrieve, and the score is the number of names written. A second lab operationalizes memory as recognition: people hear names, then later mark which names they recognize. Figure 5.1 places those two procedures next to each other. Both papers concern memory. The scores come from different operations. A reader who treats the two papers as one measurement has skipped the operational definitions.
| Lab | Construct | Operational definition |
|---|---|---|
| A | memory | After sleep, participants write every name they retrieve. Score = number of names written. |
| B | memory | Participants hear names, then later mark which names they recognize. Score = hits minus false alarms. |
Can one construct carry more than one operational definition?
Most constructs do. Extraversion can be operationalized as a questionnaire score, as talking time in a waiting room, or as the number of social events a person reports attending in a month. Each operational definition makes extraversion observable in a different way. The next article asks whether a given procedure is reliable — whether repeating that procedure yields a consistent score.
References
- Cozby, P. C., & Bates, S. C. (2020). Methods in behavioral research (14th ed.). McGraw-Hill.
Image and media credits
- Top image. A clipboard and a pencil on a desk under a lamp. It sets the scene for this lesson on operational definitions. Source: Created for this site with Grok Imagine (xAI), an AI image generator. License: Original image made for mattgaugerx.com.
