Comment on Lundh (2023).

In this commentary of Lundh's (2023) article, we point to an individualized process-based approach for the future of psychotherapy. The traditional nomothetic research paradigm is limiting our understanding of processes of change, oversimplifying psychological phenomena, and neglecting individual dynamics. In contrast, a process-based approach calls for ideographic methodologies, departing from the latent-disease paradigm toward process-based interventions. Process-based research promises avenues for enhancing intervention science and a deeper comprehension about psychopathology and therapeutic mechanisms, in a comprehensive, personalized, and holistic manner.

Setting performance and learning goals is useful for active and inactive individuals, if goals are personalized and flexible: commentary on Swann et al. (2020).

This commentary expands on the recent critical review by Swann et al. (2020) which aimed to update the applications of Goal-Setting Theory (Locke & Latham, 2019) in physical activity promotion. Drawing from other work on goal striving and behaviour change, we make four key points to further elaborate on Swann et al.'s review. First, goals are more likely to be enacted if they are specific, personally relevant and pursued for autonomous motives; performance goals can be useful for inactive individuals if set appropriately and self-endorsed. Second, goal striving needs to be flexible and adjustable, and to consider goal priorities and time factors relevant to goal engagement and disengagement. Goal-Setting Theory would therefore benefit from being expanded to add the factors of goal priority, context, and time. Third, research on goal setting in physical activity could benefit from embracing idiographic designs and interventions. Fourth, other theoretical approaches to goal striving should be considered when discussing goal setting in physical activity promotion.

Challenges and solutions for N-of-1 design studies in health psychology.

Theories of behaviour change and health behaviour change interventions are most often evaluated in between-person designs. However, behaviour change theories apply to individuals not groups and behavioural interventions ultimately aim to achieve within-person rather than between-group change. Within-person methodology, such as N-of-1 (also known as single case design), can circumvent this issue, though has multiple design-specific challenges. This paper provides a conceptual review of the challenges and potential solutions for undertaking N-of-1 studies in health psychology. Key challenges identified include participant adherence to within-person protocols, carry-over and slow onset effects, suitability of behaviour change techniques for evaluation in N-of-1 experimental studies, optimal allocation sequencing and blinding, calculating power/sample size, and choosing the most suitable analysis approach. Key solutions include involving users in study design, employing recent technologies for unobtrusive data collection and problem solving by design. Within-person designs share common methodological requirements with conventional between-person designs but require specific methodological considerations. N-of-1 evaluation designs are appropriate for many though not all types of interventions. A greater understanding of patterns of behaviours and factors influencing behaviour change at the within-person level is required to progress health psychology into a precision science. Video abstract: Supplementary Material 1.