Explaining the dropout rates

Dropout rates from this intervention were revealed to be important: 47.2% of young adults and 23.7% of older adults. This section will attempt to pin down the personal characteristics differentiating participants that completed the study from the ones that did not. For this purpose, analyses will only be conducted on dispositional characteristics (measured using questionnaires) collected upon the first session.

Repeated measures ANOVAs were conducted on the questionnaires displaying a number of subscales (i.e. MCQ30, the SIPI, the RRQ, the IAMI, and the PANAS) with Dropout (Yes, No) and Age (Young, Old) as between factors. Additionally, one-way ANOVAs with the same between factors were conducted on the remaining questionnaires (i.e. DDFS, BDI, CERQ, MAAS, WHO). An interaction between SIPI and dropout was found significant, F (2, 140) = 7.97, p < .001, ηp2 = .10. Participants who completed the study reported more positive-constructive thoughts (M = 3.16, SD = .54) and less guilt-fear of failure thoughts (M = 2.02, SD = .55) than participants who did not (Positive-constructive, M = 2.79, SD = .53; Guilt-fear of failure, M = 2.29, SD = .54), F (1, 72) = 8.09, p = .006, ηp2 = .10 and F (1, 72) = 4.25, p = .043, ηp2 = .06 respectively. Additionally, an interaction was found to be significant between PANAS and dropout, F (1, 70) = 7.18, p = .009, ηp2 = .09. Participants who completed the study reported more positive affect (M = 34.88, SD = 6.95) and less negative affect (M = 21.77, SD = 8.37)

160

than participants who did not complete it (Positive, M = 30.50, SD = .6.30; Negative, M = 17.15, SD = 5.20), F (1, 72) = 7.12, p = .009, ηp2 = .09 and F (1, 72) = 8.58, p = .005, ηp2 = .11 respectively.

6.3.4. Discussion

Despite previous work showing a reduction of mind-wandering frequency following the practice of meditation (Mrazek et al., 2013; Mrazek et al., 2012), limited work has considered the implication of heterogeneity of self-generated thoughts. The aim of this study was to measure the impact of meditation practice on different types of thoughts in young and older adults. In this perspective, participants either practiced meditation or listened to book recordings for 4 weeks. Multidimensional experience sampling was conducted before and after the intervention. As expected, the practice of meditation increased young adults’ ability to focus on a mundane task. This effect was not found for older adults, who displayed higher focus rates than young adults at baseline. A reduction of negative thoughts initially reported by Jazaieri et al. (2016) was also replicated here for both young and older adults. Preliminary findings suggest an increase of visual thoughts after the practice of meditation. Participants in the active control group reported a decrease of both past and future-oriented thoughts. Lastly, a self-selection bias was found, with participants completing the study showing high positivity and low negativity.

A growing body of literature has explored the benefits of mindfulness-based meditation on health, wellbeing and cognition (Carmody & Baer, 2008; Chiesa et al., 2011; Evans et al., 2008; Pagnoni & Cekic, 2007). Practicing meditation increases performance on attentional control and sustained attention (Anderson, Lau, Segal, & Bishop, 2007; Chambers, Lo, & Allen, 2008; Moore, Gruber, Derose, & Malinowski, 2012) and reduces mind-wandering experiences (Mrazek et al., 2013). This was replicated in the present study where young adults reported to be more on-task after the meditation training. However, it was not the case for older adults, who were more

161

on-task at baseline. Meditation practice also demonstrated a tendency to increase visual thoughts in both young and older adults (marginal finding). This can be explained either by the nature of the body-scan meditation which encourages the visualisation of different body parts, or by an increase in present moment awareness leading to better processing of the visual task.

One study looking into the impact of meditation on thought content has outlined a reduction of negative thoughts (Jazaieri et al., 2016). Similarly, the present study found a decrease of negative/past-oriented thoughts after the practice of meditation for both young and older adults. By nature, mindfulness-based meditation encourages individuals to notice bodily sensations as well as incoming thoughts. Individuals are guided to let go of these thoughts and to bring focus back to the present moment, often characterised by an object (e.g. body, breathing). Compassion features incorporated into mindfulness meditation are designed to nurture the acceptance of mind drift by reinforcing kindness toward oneself. This aspect is suspected to reduce negative thoughts. Nevertheless, the present study is not differentiating between the contribution of mindfulness and compassion features. Critically, the benefits of the present intervention may be explained by the combination of both mindfulness and compassion features. Future research should aim to disentangle the mechanisms by which meditation practice reduces negative and past thoughts. Furthermore, an avenue to ponder is the mediating role of thought content in the benefits of meditation-based interventions. Meditation practice reduces both negative thoughts, as well as behaviours related to their occurrence such as negative mood, depression and poor performance (Banks et al., 2016; Marchand, 2012; Poerio et al., 2013; Ramel, Goldin, Carmona, & McQuaid, 2004; Ruby, Smallwood, Engen, et al., 2013; Smallwood & O’Connor, 2011; Smallwood et al., 2005; Smallwood, O’Connor, et al., 2007). Therefore, the behavioural benefits of meditation practice could be driven by changes in thought content, particularly the reduction of negative/past thoughts.

162

A strength of this study was the use of an active control condition to distinguish the contribution of meditation practice from the simple practice of an activity. In the control condition, participants listened to book recordings instead of guided meditations. Young and older adults reported fewer future and past-oriented thoughts after this intervention. Similar findings were previously reported, with both meditation and listening to book recordings reducing negative mood and depressive symptoms (Zeidan, Johnson, Diamond, David, & Goolkasian, 2010). Stories used in this intervention were not personally relevant to participants. One interpretation is that this feature encouraged personal detachment from one’s current concerns. Thus, the reduction of current concerns may have led to fewer thoughts intrinsically linked to the self, namely future and past-oriented thoughts. Comparing this to the effect of meditation practice, it seems that the benefits of meditation lies in the selectivity of the changes. While past-oriented thoughts are merely detrimental, future-oriented thoughts are more beneficial for everyday functioning (Banks et al., 2016; Engert et al., 2014; Poerio et al., 2013; Ruby, Smallwood, Engen, et al., 2013). Hence, the practice of meditation seems to target disadvantageous thoughts, while preserving more advantageous ones.

Finally, an exploratory approach was taken to uncover individual characteristics underlying participants’ engagement in the study. Participants who completed the full study showed high positive affect and positive-constructive thoughts, as well as low negative affect and guilt-fear of failure thoughts at baseline. Positive and constructive thoughts imply a positive approach, where self-generated thoughts are seen as worthwhile and stimulating. On the other hand, guilt and fear of failure refer to a negative approach where they are seen as negative and frightening (Huba et al., 1982). The self- selective bias observed here suggests that self-efficacy is indispensable to the fulfilment of a time-consuming experiment. Participants’ optimistic and pessimistic take on life may be an underlying factor encouraging study completion. Importantly, this

163

brings a new perspective to the previously discussed findings. Firstly, the generalisation of the intervention effects described beforehand is limited. Secondly, failure to replicate a reduction of past-oriented thoughts and an increase of visual thoughts in ageing may be bound to this selectivity bias. Indeed, despite all participants in the second experiment taking part in the first one, age-effects found in experiment one (i.e. fewer past-oriented thoughts). While the lack of statistical power should be kept in mind, future studies may want to consider individual differences as factors influencing intervention outcomes.