Abstract：
Planning-based interventions are often used to help individuals form habits. Existing literature suggests a one-size-fits all approach to habit formation, but planning interventions may be optimized if tailored to individual differences and/or behavioral complexity. We test the hypothesis that planning to do a relatively complex behaviour (exercise) at a time that matches an individuals\' diurnal preference will facilitate behavioral engagement; whereas for a simpler behaviour (calcium supplementation), the optimal time-of-day for a new behavior will occur in the morning. Young, women volunteers (N = 317) were randomly assigned to take calcium supplements or to exercise for 4 weeks and to control (no planning) or to one of three planning interventions (morning plan; evening plan; unassigned-time plan). Participants reported diurnal preference at baseline and habit strength and behavioral frequency weekly. Fitbit Zips and Medication Event Monitoring System Caps (MEMS) were used to objectively assess behavioral engagement. Multilevel modelling found that calcium-supplementation was greatest for morning-types in the morning-cue condition, whereas exercise was greatest for morning-types with morning cues and evening-types with evening cues. Habit-formation strategies may depend on diurnal preference and behavioral complexity. Future research can evaluate the role of other individual differences.
摘要：
基于计划的干预措施通常用于帮助个人养成习惯。现有文献提出了一种一刀切的习惯形成方法，但是，如果针对个体差异和/或行为复杂性进行定制，则计划干预措施可能会得到优化。我们检验了以下假设：计划在与个人的昼夜偏好相匹配的时间进行相对复杂的行为（锻炼）将促进行为参与；而对于更简单的行为（补钙），新行为的最佳时间将发生在早晨。年轻,女性志愿者(N=317)被随机分配服用钙补充剂或运动4周,并进行对照(无计划)或接受3项计划干预措施之一(早计划;晚计划;未分配时间计划).参与者每周报告基线时的昼夜偏好以及习惯强度和行为频率。FitbitZips和药物事件监测系统帽（MEMS）用于客观评估行为参与。多水平模型发现，在早晨提示条件下，早晨类型的补钙作用最大，而锻炼对于早晨提示的早晨类型和晚上提示的晚上类型是最大的。习惯形成策略可能取决于昼夜偏好和行为复杂性。未来的研究可以评估其他个体差异的作用。
