Module 2: Constructs and operational definitions

explain what makes psychological research unique

• Some fields research things that are relatively easy to observe and measure e.g. height

• Psychological research is more challenging as many things investigated are intangible mechanisms/ attributes (not easily measureable or observable)

• e.g. happiness is subjectively commonly experienced however we cannot touch or observe it directly -> is a construct / abstract atrribute

  • To measure happiness - we could observe smiling behaviour - measureable behaviour that we theorise indicate happiness

  • While we cannot observe happiness directly we can measure other things that we theorise associate with it

What is a construct?

•  hypothetical/intangible attributes that we theorise underlie observable behaviour

• They are not directly observable or measureable as they often represent tendencies to think, feel or act

  • e.g. just because someone is decribed as extroverted does not mean they are acting so right now -> not observable

  • Also as involve internal processes -> fear involves peripheral nervous system + thoughts/ feelings none of which may be easily observed to outside observers

  • None can be reduced to a specific or particular thought, feeling, act or physiological response - rather are summaries of sets of behaviours and internal processes

• These incldue personality traits, emotional states, attitudes and abilities

• Weight is NOT a construct as it can be measured - a set of bathroom scales would be a measure of weight

What is an operational defintion?

• When we measure / observe a construct indirectly through an observable behaviour - this becomes the operational definition of the construct (see happiness example)

  • Self-report measures, behvioural measures (e.g. backward digit span), physiological measures (e.g. heart rate)

• If we wish to measure/ observe a consturct we must operationalise it

• Observation and measurement of these measureable behaviours are just one of the operational definitions of the numerous ways possible

• Crucial note : operational defintion does not equal/ refer to the construct - rather how we observe or define the construct indirectly

• e.g. intelligence is a construct -> physically intangible ; operational definition - performance on IQ test

• An operational defintion can be anything that could indicate a construct (e.g. mental health days off for wellbeing) - its appropriateness does not take away from this (rather from the reliability of the experiment itself)

  

What are limitations of operational definitions?

• Although necessary to research particular constructs - keep in mind that operational defintions are not entire reflections of the contruct + are not the same

• They only provide an indication and have differing appropriateness or accuracy

• There is not a one-to-one relationship between the variable being measured and the actual measurements produced (i.e. three things being observed/ investigated opposed to two)

• e.g. knoweldge - operationalised through a test; however while physical sickness would affect performance on the test - it would likely not affect knoweldge itself

• Two problems that arise:

  1. Operational defintions may leave out parts of the construct e.g. depression operationalised in terms of behavioural symptoms

     • i.ie insomnia  - whereas depression also involves emotional and cognitive components now left behind

     • Solution: use multiple procedures measuring the same variable -> converging operations (within or across studies)

       • When these produce similar correlations or outcomes - this is often good evidence

  2. Operational defintions may include extra components not part of the contruct

     • e.g. self report/ questionarre influence by verbal skills (ability to understand questions and express) as well as willingness to reveal this

 

• Best ways to operationalise is to consult previous studies + research

What is measurement?

is the assignment of scores to individuals so that the scores represent some characteristic of the individuals. (e.g. weighing onself on scales)

What is psychometrics?

psychological measurement (e.g. backward digit span tasks for memory capcity, or self reports)