Читать книгу Methods in Psychological Research - Annabel Ness Evans - Страница 78

Many cold remedies display warnings that they should never be taken with alcohol. It is often the case that these drugs can cause drowsiness, but this cause-and-effect relationship is increased with the consumption of alcohol. In this example, alcohol is acting as a moderating variable by amplifying the drowsiness effect of the drug. Moderating variables act to influence the relationship between the IV and the DVs. A moderating variable can increase, decrease, or even reverse the relationship between the IV and the DVs. If, as discussed previously, the IV is the cause in the cause-and-effect relationship and the DV is the effect in the cause-and-effect relationship, the moderating variable is a third influence that must be taken into account to clearly describe the cause-and-effect relationship. For example, in his famous studies on obedience, Milgram (1974) found that the actions of a confederate-companion (someone posing as a participant who is actually part of the study) could produce a strong moderating effect. When the confederate-companion agreed to shock the learner, 93% of the true participants continued to administer shocks, but when the confederate disobeyed the order, only 10% of the true participants continued.

In the Knez (2001) study of the effect of light on mood, gender was identified as a moderating variable. Relative to cool light, warm lighting produces a more positive emotional response in women than it does in men. Therefore, the influence that lighting has on mood is moderated by the gender of the participant.

In a recent study conducted in Islamabad, Altaf and Awan (2011) examined how spirituality moderates the relationship between office workload and job satisfaction. By surveying 76 employees, they assessed the relationship between workload, workplace spirituality, and level of job satisfaction. Workplace spirituality is a person’s sense of meaning and purpose. They found that spirituality was positively related to job satisfaction, but they didn’t find the negative relationship between workload and job satisfaction that had been reported in the literature (Khan, 1980, as cited in Altaf & Awan, 2011). They suggest that workplace spirituality moderates the usually negative effect of workload on job satisfaction. Essentially, if a workplace fosters an environment where employees find spiritual meaning, a heavy workload does not reduce job satisfaction. (For more information on moderating variables, see the discussion of factorial designs in Chapter 7.)

The following diagrams illustrate different relationships between IVs and DVs, including how other variables can affect a relationship.

This diagram shows a direct relationship between an IV and a DV.

For example,

 IV DV

 Condom use Sexually transmitted infections (STIs)

Condom use is directly related to incidence of STIs in sexually active young people.

This diagram illustrates how the relationship between the IV and the DV is changed by another variable. The moderating variable may strengthen, weaken, or nullify the relationship between the IV and the DV.

For example,

 IV Moderating variable DV

 Condom use Age STI

If the causal relationship between condom use and STIs is stronger in younger people, perhaps because they are having more sex with more partners, and weaker in older people, who tend to be in monogamous relationships, then age moderates the effect of condom use on STI incidence.

This diagram demonstrates when the relationship between the IV and the DV is accounted for by another variable.

For example,

 IV Mediating variable DV

 Level of education Condom use STI

If highly educated people have fewer STIs than poorly educated people, condom use might be a mediating variable. The relationship between level of education and STI incidence is explained by the greater use of condoms by better-educated people.