IMPROVING NUMERACY IMPROVES HEALTH BEHAVIORS

Purpose: To study numeracy’s causal impact on health-related decision outcomes through a values affirmation exercise.

Method: Undergraduates enrolled in statistics class completed tests of general mathematical ability (i.e., objective numeracy), indicated their perceived mathematical ability and preference for numbers (i.e., subjective numeracy), and provided self-reports of health-related behaviors (e.g., “In the past 3 months, have you forgotten to take your medication?”) at the beginning and end of the semester.  At the beginning of the semester, students were randomly assigned to complete a short writing exercise in which they rank-ordered a list of values (e.g., relationships with family/friends, spirituality/religion) from most important to least important, and wrote a paragraph about either their most important value and why it is important to them (values affirmation), or their least important value and why it might be important to others (control). Previous research has shown that affirming values provides individuals with psychological resources to cope with threats, such as learning difficult material and receiving negative feedback, but no known research has tested whether values affirmation will improve numeracy and whether hypothesized numeracy improvements might improve health-related behaviors. 

Result: Affirming values caused improvements in both objective numeracy (M_affirmation= 23.56(4.75), M_control= 21(6.60); p<.01) and subjective numeracy (M_affirmation= 4.35(.83), M_control= 4.08(.78); p=.02). Control participants had significantly worse health outcomes at the end of the semester (M_time1= .71(.16), M_time2= .66(.16), p<.01), whereas the values-affirmation exercise protected participants from these small declines in health-related outcomes over the semester (M_time1= .69(.17), M_time2= .68(.16), ns).  Path analyses indicated that the superior health outcomes of value-affirmed participants were due to improvements to objective numeracy (total indirect effect of values affirmation on health = .01 [95% CI = .002, .03]); improved subjective numeracy showed no effects on health. 

Conclusion: Improving objective numeracy caused corresponding improvements to health behavior. Giving people resources to help them cope with a difficult math class helped them improve their objective numeric ability and become more comfortable and confident with their numeric abilities. Ultimately, the numeracy gains also produced better health behaviors. These findings provide the first known evidence of the causal effects of numeracy on health and underscore the importance of improving numeracy in patients and others.