Background: Mediation studies test the mechanisms by which interventions produce clinical outcomes. Consistent positive mediation results have previously been evidenced (Hayeset al., 2006) for the putative processes that compromise the psychological flexibility model of acceptance and commitment therapy (ACT).Aims: The present review aimed to update and extend the ACT mediation evidence base by reviewing mediation studies published since the review of Hayeset al.(2006).Method: ACT mediation studies published between 2006 and 2015 were systematically collated, synthesized and quality assessed.Results: Twelve studies met inclusion criteria and findings were synthesized by (a) the putative processes under investigation, and (b) the outcomes on which processes were tested for mediation. Mediation results were found to be generally consistent with the psychological flexibility model of ACT. However, studies were limited in methodological quality and were overly focused on a small number of putative processes.Conclusions: Further research is required that addresses the identified methodological limitations and also examines currently under-researched putative processes.

The idea that people can experience two oppositely valenced emotions has been controversial ever since early attempts to investigate the construct of mixed emotions. This meta-analysis examined the robustness with which mixed emotions have been elicited experimentally. A systematic literature search identified 63 experimental studies that instigated the experience of mixed emotions. Studies were distinguished according to the structure of the underlying affect model – dimensional or discrete – as well as according to the type of mixed emotions studied (e.g., happy-sad, fearful-happy, positive-negative). The meta-analysis using a random-effects model revealed a moderate to high effect size for the elicitation of mixed emotions (dIG+ = .77), which remained consistent regardless of the structure of the affect model, and across different types of mixed emotions. Several methodological and design moderators were tested. Studies using the minimum index (i.e., the minimum value between a pair of opposite valenced affects) resulted in smaller effect sizes, whereas subjective measures of mixed emotions increased the effect sizes. The presence of more women in the samples was also associated with larger effect sizes. The current study indicates that mixed emotions are a robust, measurable and non-artifactual experience. The results are discussed in terms of the implications for an affect system that has greater versatility and flexibility than previously thought.

Generalized anxiety disorder (GAD) is a common disorder in older adults producing functional impairment, and psychotherapy is the preferred treatment option. Meta-analytic methods sought to determine the efficacy of outpatient cognitive behavioral therapy (CBT) with respect to the hallmark feature of GAD-uncontrolled and excessive worry. In order to optimize clinical applicability, variables associated with GAD treatment outcomes were also examined. Systematic search of relevant databases and iterative searches of references from articles retrieved. All studies were required to have been a randomized control trial (RCT), to have used the Penn State Worry Questionnaire (PSWQ) or its abbreviated version (PSWQ-A) as an outcome measure, and to have conducted CBT with outpatient older adults. Fourteen RCTs (N = 985) were suitable and random-effects meta-analyses and univariate meta-regressions were conducted. At the end of treatment, and at 6-month follow-up, significant treatment effects favoring CBT were found in comparison to a waitlist or treatment-as-usual. When CBT was compared with active controls, a small nonsignificant treatment advantage was found for CBT at the end of treatment, with equivalence of outcomes at follow-up. Treatment effect size of CBT for GAD was significantly associated with attrition rates and depression outcomes. CBT is more helpful than having no treatment for GAD in later life. Nevertheless, whether CBT shows long-term durability, or is superior to other commonly available treatments (such as supportive psychotherapy), remains to be tested. The relationship between treatment effects for GAD and depression following CBT warrants further research.

This research investigated whether (1) the experience of mixed emotions is a consequence of activating conflicting goals and (2) mixed emotions are distinct from emotional conflict. A preliminary experiment (Study 1, N = 35) showed that an elicited goal conflict predicted more mixed emotions than a condition where the same goals were not in conflict. The second experiment was based on naturally occurring goal activation (Study 2, N = 57). This illustrated that mixed emotions were experienced more following conflicting goals compared with a facilitating goals condition-on both a direct self-report measure of mixed emotions and a minimum index measure. The results also showed that mixed emotions were different to emotional conflict. Overall, goal conflict was found to be a source of mixed emotions, and it is feasible that such states have a role in resolving personal dilemmas.

Affective experiences can fluctuate, be combined, and fused, resulting in various phenomena labeled as being emotionally complex. Despite the lack of a common theoretical framework, several phenomena including mixed emotions, emodiversity, meta-emotions, awe, among several others, have been defined as being emotionally complex. In this conceptual analysis, I aim to integrate the diversity of emotional complexity by describing various phenomena associated with this construct. This integration offers a more comprehensive panorama of the current usage of the concept of emotional complexity compared to previous attempts to consolidate the field. Furthermore, this conceptual analysis intends to disentangle the emotional fingerprints of emotional complexity. In particular, I present evidence and arguments showing that complex emotions can be characterized as having specific facial expressions, appraisals, and functional significance. Finally, I suggest that it is possible to describe emotional complexity using concepts and properties from the complex systems theory. Concepts such as the hierarchical organization of the affect system and emergent self-organization are used to explain current evidence on emotional complexity. I explain that applying complex systems theory to emotional complexity is not only theoretically convenient, but that complex systems theory also serves to advance new forms to conceptualize the affect system. The current conceptual analysis can help to organize current research and theory in order to encourage new research endeavors in the field of emotional complexity and acknowledge the importance of emotional complexity in models of affect, for which I suggest some specific guidelines.