As Suddendorf & Corballis (S&C) aptly point out, present evidence suggests that mental time travel is a specifically human phenomenon. This holds true, however, for other abilities as well, particularly theory of mind. This presents no problem for the contemporary “modularity” trend, as one can easily imagine any number of competences that are independent and domain-specific but emerge in phylogenetic synchrony, all the same, because they require cooperation in order to become functional. S&C appear to think along this line as well when they refer to theory of mind among the tools necessary for time travel, although they remain somewhat vague as to exactly how folk psychology contributes to a concept of time. Nonetheless, the assumption that time travel and theory of mind are outcomes of separate mechanisms poses the difficulty that their joint emergence occurs not only in phylogeny but in ontogeny, as well. We were able to show in a sample of 170 children that at around the fourth birthday a set of new competences synchronously develop. They include: a theory of mind as tested in a false-belief paradigm; time comprehension as demonstrated by predicting and comparing the running times of hourglasses; and the abilities to delay gratification, to temporally organize conflicting desires, and to anticipate future needs (Bischof-Köhler Reference Bischof-Köhler2000). The correlation between these competences is age-independent. It would be difficult, in fact, to identify any vital necessity requiring their joint functioning at such an early age. All this suggests that these competences rest on a common mechanism.
We consider “frame-of-reference awareness” to be that mechanism. The term frame of reference was introduced by Gestalt theorists. Koffka (Reference Koffka1935) thoroughly dealt with it under the label “framework” as distinguished from “things.” If a feature of a thing is perceived as its absolute property, but is actually relative to its surrounding background, then the latter acts as a frame of reference for the former. Take size, for example. People in an Ames’ room appear to grow or shrink when their position is shifted from one corner to the other. This effect is actually due to the background's geometry, but the observer, even if cognizant of the trick, is unable to perceive it this way. Gestaltists have primarily used the frame-of-reference concept to account for perceptual constancy phenomena. Koffka pointed out, though, that it can also be applied to social constructs like “civilization,” and Lewin (Reference Lewin and Carmichael1946) was among the first to extend it even further to motivational phenomena. Lewin stated that a toy might have a different emotional valence to a child depending on whether or not the mother is present, and explicitly compared this effect to the varying appearance of an object's size or color against different backgrounds. Following this line of thought, we may consider that motivation in general functions as a frame of reference that supplies a mood background organizing the valence profile of life space. Different things become salient, and the world takes on differing physiognomy for a subject when it is hungry, or alarmed, or in love.
Usually, frame-of-reference activity remains inconspicuous or, as Wolfgang Köhler put it, “silent.” Only when contradicting frames overlap and cause experiential ambiguities, does one become aware of them. We postulate that the potential for this awareness is beyond the grasp of even the great apes and thus a core constituent of the human condition.
Mental time travel unquestionably requires the ability to reflect upon frames of reference. A shifting of temporal coordinates is necessary in order to conceive of a forthcoming event in the past tense by imagining it from an even further future perspective. Foresight as such, however, does not yet require frame-of-reference awareness. What really matters is foresight of need states, that is, of motivational frames of reference other than the ones shaping the present world view. But why should it be necessary to imagine non-present need states in the first place? The answer leads to the core assumption of the Bischof-Köhler hypothesis. It deals with the problem of motive priority management. Animals, when experiencing contradicting needs, cannot but follow the strongest need and suppress the others. Humans may still behave the same way, but they have access to a higher level of behavioral organization. They are able to conceive of a temporal axis analogous to space that provides a buffer on which competing desires, including future ones, may be shifted, postponed, adjourned, delayed, or anticipated, according to their expected consummatory value and success, thus overriding the imperative of instant gratification. The advantage of such an arrangement is obvious. The use of fire, for example, would not have been practicable for our ancestors had they not been able to collect firewood well before commencing to freeze.
Obviously, theory of mind can also be interpreted as frame-of-reference awareness. Understanding false belief, as well as Flavell's level II perspective taking, depend on the ability to simultaneously represent contradicting frames of reference. Rephrasing theory of mind in such a way goes beyond describing the same issue in different theoretical languages. Usually the selective advantage of theory of mind is seen as an improvement of social-cognitive folk psychology. However, if we conceive of it as frame-of-reference awareness instead, we describe it as a multipurpose “module” whose adaptive function is much more general. Looked at in this way, mental time travel and theory of mind need not be externally arranged in a means–end relation, but appear as different outcomes of one and the same competence.
