In Hoerl & McCormack's (H&M's) dual systems account of temporal cognition, the primitive mechanisms and mental representations involved in “temporal updating” are not sufficient for “temporal reasoning.” A key question about the relationship between the two proposed systems is not fully addressed, however. What role, if any, do mechanisms of temporal updating play in the subsequent development of the temporal reasoning system? Despite being insufficient to support mature temporal reasoning on their own, evolutionarily ancient representations of time could nonetheless provide the initial building blocks from which the temporal reasoning system is built. Here, I will present developmental evidence suggesting that this is not the case. Instead, I propose that language and culture are the primary sources of the abstract conception of time.
Before addressing the sources of the temporal reasoning (TR) system, we must be clear about the nature of this system. H&M discuss many capacities, such as mental time travel, which they argue are only allowed by the TR system. Here, however, I will focus on their central claims about the format of this representational system itself. Specifically, they describe a model of “time itself” that is linear, unidirectional, and includes a conceptual distinction between the past and future. I concur with the assessment that there is currently no compelling evidence that non-human animals or human infants possess such a model of time.
How might the TR system be constructed in the mind of a child, and what are its developmental sources? Importantly, H&M do not claim the dual systems are completely independent of one another. They allow that mechanisms involved in the temporal updating system can also be involved in temporal reasoning, and, further, that they may “ground” the TR system. This idea bears similarity to existing theoretical accounts of abstract concept acquisition in which innate, perceptual primitives play a critical role (Carey Reference Carey2009; cf. Barner Reference Barner2017). On the dual systems account, temporal updating processes cannot be the only source of TR. However, the account is consistent with the possibility that primitive temporal representations – for example, of duration and order – provide the source material for the subsequent development of TR. Relatively little attention is given to other potential sources.
By examining how adult ways of representing time are initially understood by children, we may uncover clues about the developmental origins of TR. In industrialized cultures, adults constantly engage in TR by using explicit symbolic systems. We use words to describe and label different aspects of “time itself,” and we use artifacts like clocks and calendars to visually represent an invisible temporal dimension. Learning to use these symbolic systems is slow and arduous, and many children continue to struggle with this long after the 3- to 5-year-old developmental window that is the focus of the target article (Friedman & Laycock Reference Friedman and Laycock1989; Kamii & Russell Reference Kamii and Russell2012). Nonetheless, children start learning early, and even 2-year-olds produce abstract, time-related words (Ames Reference Ames1946).
As H&M point out, simply being able to say temporal words should not be taken as evidence that children fully understand them, or that they have TR capacities that would allow this. Relevant to this, beyond the early studies of “before” and “after,” more recent research has examined children's acquisition of additional classes of time words (Busby & Suddendorf Reference Busby and Suddendorf2005; Busby-Grant & Suddendorf Reference Busby-Grant and Suddendorf2011; Shatz et al. Reference Shatz, Tare, Nguyen and Young2010; Tillman & Barner Reference Tillman and Barner2015; Tillman et al. Reference Tillman, Marghetis, Barner and Srinivasan2017; Zhang & Hudson Reference Zhang and Hudson2018a). These other lexical categories are linked to key facets of the adult TR system. For example, our use of duration words, like “minute,” implies that time is an absolute, measurable dimension. Deictic time words, like “yesterday,” reference non-present locations in a linear temporal array, and (in English) are specific to the past or the future. In each case, there are multiyear gaps between children's first usage and eventual adult-like comprehension. However, as discussed below, children's early errors with time words are non-random, and reflect a gradual accumulation of knowledge about the temporal domain.
Most relevant to the dual systems perspective, studies of time-word learning suggest that primitive representational systems may play little, if any, role in the initial construction of symbolic representations of time. The first aspects of time-word meanings that children learn are precisely those that H&M argue the temporal updating system cannot support. For example, preschoolers infer that time words reference the domain of time; that they have systematic, ordered relationships with other time words, and that they reference either the past or the future (Harner Reference Harner1975; Shatz et al. Reference Shatz, Tare, Nguyen and Young2010; Tillman & Barner Reference Tillman and Barner2015; Tillman et al. Reference Tillman, Marghetis, Barner and Srinivasan2017). In contrast, most children do not appear to map these words to perceptual representations of duration until two or three years later (Tillman & Barner Reference Tillman and Barner2015). This trajectory suggests that the updating and reasoning systems may be more independent than H&M suggest.
If children are not using primitive temporal representations, what sources of information do they use to acquire the TR system? The facets of time-word meaning that are most readily learned by children are those most easily inferred from adult speech, indicating that linguistic and narrative structure may support the acquisition of abstract temporal concepts (Tillman et al. Reference Tillman, Marghetis, Barner and Srinivasan2017). Further, children's knowledge of exact definitions drives their ability to link time words with approximate temporal durations, suggesting that formal education may be a requirement (Tillman & Barner Reference Tillman and Barner2015).
In the target article, language and education are only briefly discussed, and cultural differences in temporal cognition are largely characterized as embellishments of a universal view. However, recent research on the effects of language, literacy, and education on mental representations of time suggest that they play a significant role (Bergen & Lau Reference Bergen and Lau2012; Boroditsky & Gaby Reference Boroditsky and Gaby2010; Brislin & Kim Reference Brislin and Kim2003; Hendricks & Boroditsky Reference Hendricks and Boroditsky2017; Tillman et al. Reference Tillman, Marghetis, Barner and Srinivasan2017). Moving forward, developmental scientists must continue to explore the specific roles of language and cultural transmission in early TR. In our quest for the psychological origins of time, these factors may prove more important than forms of representation shared with animals.
In Hoerl & McCormack's (H&M's) dual systems account of temporal cognition, the primitive mechanisms and mental representations involved in “temporal updating” are not sufficient for “temporal reasoning.” A key question about the relationship between the two proposed systems is not fully addressed, however. What role, if any, do mechanisms of temporal updating play in the subsequent development of the temporal reasoning system? Despite being insufficient to support mature temporal reasoning on their own, evolutionarily ancient representations of time could nonetheless provide the initial building blocks from which the temporal reasoning system is built. Here, I will present developmental evidence suggesting that this is not the case. Instead, I propose that language and culture are the primary sources of the abstract conception of time.
Before addressing the sources of the temporal reasoning (TR) system, we must be clear about the nature of this system. H&M discuss many capacities, such as mental time travel, which they argue are only allowed by the TR system. Here, however, I will focus on their central claims about the format of this representational system itself. Specifically, they describe a model of “time itself” that is linear, unidirectional, and includes a conceptual distinction between the past and future. I concur with the assessment that there is currently no compelling evidence that non-human animals or human infants possess such a model of time.
How might the TR system be constructed in the mind of a child, and what are its developmental sources? Importantly, H&M do not claim the dual systems are completely independent of one another. They allow that mechanisms involved in the temporal updating system can also be involved in temporal reasoning, and, further, that they may “ground” the TR system. This idea bears similarity to existing theoretical accounts of abstract concept acquisition in which innate, perceptual primitives play a critical role (Carey Reference Carey2009; cf. Barner Reference Barner2017). On the dual systems account, temporal updating processes cannot be the only source of TR. However, the account is consistent with the possibility that primitive temporal representations – for example, of duration and order – provide the source material for the subsequent development of TR. Relatively little attention is given to other potential sources.
By examining how adult ways of representing time are initially understood by children, we may uncover clues about the developmental origins of TR. In industrialized cultures, adults constantly engage in TR by using explicit symbolic systems. We use words to describe and label different aspects of “time itself,” and we use artifacts like clocks and calendars to visually represent an invisible temporal dimension. Learning to use these symbolic systems is slow and arduous, and many children continue to struggle with this long after the 3- to 5-year-old developmental window that is the focus of the target article (Friedman & Laycock Reference Friedman and Laycock1989; Kamii & Russell Reference Kamii and Russell2012). Nonetheless, children start learning early, and even 2-year-olds produce abstract, time-related words (Ames Reference Ames1946).
As H&M point out, simply being able to say temporal words should not be taken as evidence that children fully understand them, or that they have TR capacities that would allow this. Relevant to this, beyond the early studies of “before” and “after,” more recent research has examined children's acquisition of additional classes of time words (Busby & Suddendorf Reference Busby and Suddendorf2005; Busby-Grant & Suddendorf Reference Busby-Grant and Suddendorf2011; Shatz et al. Reference Shatz, Tare, Nguyen and Young2010; Tillman & Barner Reference Tillman and Barner2015; Tillman et al. Reference Tillman, Marghetis, Barner and Srinivasan2017; Zhang & Hudson Reference Zhang and Hudson2018a). These other lexical categories are linked to key facets of the adult TR system. For example, our use of duration words, like “minute,” implies that time is an absolute, measurable dimension. Deictic time words, like “yesterday,” reference non-present locations in a linear temporal array, and (in English) are specific to the past or the future. In each case, there are multiyear gaps between children's first usage and eventual adult-like comprehension. However, as discussed below, children's early errors with time words are non-random, and reflect a gradual accumulation of knowledge about the temporal domain.
Most relevant to the dual systems perspective, studies of time-word learning suggest that primitive representational systems may play little, if any, role in the initial construction of symbolic representations of time. The first aspects of time-word meanings that children learn are precisely those that H&M argue the temporal updating system cannot support. For example, preschoolers infer that time words reference the domain of time; that they have systematic, ordered relationships with other time words, and that they reference either the past or the future (Harner Reference Harner1975; Shatz et al. Reference Shatz, Tare, Nguyen and Young2010; Tillman & Barner Reference Tillman and Barner2015; Tillman et al. Reference Tillman, Marghetis, Barner and Srinivasan2017). In contrast, most children do not appear to map these words to perceptual representations of duration until two or three years later (Tillman & Barner Reference Tillman and Barner2015). This trajectory suggests that the updating and reasoning systems may be more independent than H&M suggest.
If children are not using primitive temporal representations, what sources of information do they use to acquire the TR system? The facets of time-word meaning that are most readily learned by children are those most easily inferred from adult speech, indicating that linguistic and narrative structure may support the acquisition of abstract temporal concepts (Tillman et al. Reference Tillman, Marghetis, Barner and Srinivasan2017). Further, children's knowledge of exact definitions drives their ability to link time words with approximate temporal durations, suggesting that formal education may be a requirement (Tillman & Barner Reference Tillman and Barner2015).
In the target article, language and education are only briefly discussed, and cultural differences in temporal cognition are largely characterized as embellishments of a universal view. However, recent research on the effects of language, literacy, and education on mental representations of time suggest that they play a significant role (Bergen & Lau Reference Bergen and Lau2012; Boroditsky & Gaby Reference Boroditsky and Gaby2010; Brislin & Kim Reference Brislin and Kim2003; Hendricks & Boroditsky Reference Hendricks and Boroditsky2017; Tillman et al. Reference Tillman, Marghetis, Barner and Srinivasan2017). Moving forward, developmental scientists must continue to explore the specific roles of language and cultural transmission in early TR. In our quest for the psychological origins of time, these factors may prove more important than forms of representation shared with animals.