Spontaneous thoughts occur by default in the interstices between directed, generally taskoriented
thoughts or moments of perceptual scrutiny. Their contents are overwhelmingly related
to thinkers’ current goals, either directly or indirectly via associative networks, including to past
and tentative future goals. They are triggered by ambient goal-related stimuli or segments of own
thought. Most spontaneous thought segments are very brief, a matter of seconds, but may be
much longer. Their typical brevity generally permits wide variation in content, reflecting the
individual’s current agenda of goals. Their evocation is accompanied by emotional responses
that vary widely in type, valence, and intensity. These properties of the emotional
accompaniments probably determine which content area receives priority for thought. Given
these properties of thought flow, spontaneous thoughts are highly adaptive as (1) reminders of
the individual’s larger agenda of goals while occupied with pursuing any one of them, (2)
promotion of planning for future goal pursuits, (3) review and deeper understanding of past goalrelated
experiences, and (4) development of creative solutions to problems in goal pursuit. In the
face of threats to successful pursuit of important goals or the prospect of failure, the same
mechanisms may occasion repetitive but unproductive thoughts about the pursuit, the
consequences of the failure, or the self, and strong negative emotions steering the train of
thought may lead to narrowing of its focus, thus producing rumination. The disposition to
ruminate is in part a function of states of negative affect and individual differences such as
strength of focus on particular thought themes, momentum of particular emotional states, and
neuroticism. Rumination is a common occurrence during low mood or outright depression that
accompanies the process of disengaging from goal pursuits that have become unrealistic or
overly expensive. The typically reduced interest in alternative goals during this phase further
limits the range of thought content and the individual’s resources for re-engagement with
gratifying goal pursuits. For assessment and clinical purposes, spontaneous thought content can
potentially provide information not captured by other procedures. When an individual’s
spontaneous thoughts are themselves problematic, empirically validated methods for improving
the individual’s motivational structure provide a likely best treatment strategy
