Reversals of task duration estimates: Thinking how rather than why shrinks duration estimates for simple tasks, but elongates estimates for complex tasks

Individuals often estimate the duration of tasks that others are engaged in (time a colleague would take to write a report, time a spouse would take to get dressed for a party, etc.). Construal-level theory suggests that thinking about ‘how’ (vs. ‘why’) a task is to be completed shrinks duration estimates. We argue that this effect arises for simple tasks, but complex tasks yield a reversal. Specifically, because ‘how’ participants are more attuned to the greater number of steps required for complex tasks, thinking ‘how’ (vs. ‘why’) elongates estimates. In four experiments, we test this theory using different scenarios, manipulated and measured complexity, and subjective and objective time estimates. Support emerges for the reversal, and for mediation via the perceived number of steps. Implications arise for four research domains: (a) construal level, (b) estimates of task duration, (c) planning fallacy, and (d) task complexity.