Dorien Bangma

52 | CHAPTER 3 the internal and external validation analyses support this finding. Previous research suggested that this decline in FDM can be attributed to a decrease in deliberative processes and executive functioning (Braver & West, 2008; Bruine de Bruin et al., 2012; Denburg & Hedgcock, 2015; Peters et al., 2007), in particular inhibition (Del Missier et al., 2010) and working memory (Del Missier et al., 2013). Indeed, in the current study 40% of variance of the performance on the CDR was explained by numeracy, planning and working memory, indicating that the ability to apply rules is a complex and cognitively demanding aspect of FDM. Furthermore, numeracy and planning appear to mediate the effects of aging on the CDR, however, these cognitive functions cannot completely explain the relation between age and this aspect of FDM. Furthermore, no evidence was found for a compensation effect of affective decision-making or experience for the performance on the CDR. Taken together, these results indicate that besides an age-related cognitive decline, also other variables are related to age-related difficulties in (financial) decision-making based on preferences and rules. In summary, normal aging appears to have a differential effect on various aspects of FDM. Regarding relatively basic aspects (i.e., financial competence, (financial) decision- making capacity, financial decision styles and the quality of intuitive and deliberative decisions) no evidence for effects of normal aging were found. On the other hand, an aspect of FDM that has been associated with affective processes (i.e., impulsive buying tendency) seems to improve with advancing age. Furthermore, a more complex aspect of FDM (i.e., the ability to apply rules) appears to deteriorate with advancing age. Whether or not normal aging has an effect on FDM with implications for the future and emotional decision-making remains inconclusive. The possible influence of third variables (i.e., personal finances and level of education) needs further investigation in order to provide more insight into the effects of normal aging on these aspects of FDM. When exploring the associations between performances on neuropsychological tests and FDM tests only weak and non-significant associations were found (see Appendix 3-2). This indicates that standard neuropsychological tests cannot be used to evaluate one’s ability to make financial decisions, which emphasize the importance of the development of reliable FDM measurements. However, it must be noted that we might have failed to reveal existing effects (beta-errors) due to a conservative method to control for alpha-error growth in multiple testing (i.e., Bonferroni correction). Furthermore, the inclusion of a healthy sample without distinct cognitive dysfunctions may also account for the lack of coherence between cognition and aspects of FDM due to small inter-individual differences or ceiling effects within the sample. A sample of individuals with distinct cognitive impairment might show stronger relations between aspects of FDM and measures of cognition. Finally, when exploring the associations between the different FDM tests, it was found that all correlations were of a weak to negligible size (see Appendix 3-3). This shows that there is no or only little overlap between the tests which supports the assumption of the existence of multiple independent aspects of FDM. A limitation of the current study is that the education level of our sample was slightly higher than the average education level in The Netherlands. This problem of representativeness of samples is, unfortunately, a common problem that is difficult to counter in scientific research with humans (Henrich et al., 2010). Second, the eight aspects of FDMmight not reflect all FDM