Hoerl & McCormack (H&M) present a dual timing theory through which they claim that children are incapable of reasoning about time until the age of 5, when the temporal reasoning system becomes available. The proposed dual timing system, however, neglects a significant body of literature detailing timing in the absence of symbols and/or language (i.e., non-symbolic timing; Meck & Church Reference Meck and Church1983; vanMarle & Wynn Reference vanMarle and Wynn2006; Odic, Reference Odic2018; Odic et al. Reference Odic, Lisboa, Eisinger, Olivera, Maiche and Halberda2016; for a review in animals, see Gibbon Reference Gibbon1977). By ignoring this body of evidence, the authors greatly undermine infants and children's timing abilities. In particular, substantial research reveals both infants and children are able to track durations non-symbolically (Brannon et al. Reference Brannon, Suanda and Libertus2007; Droit-Volet & Wearden Reference Droit-Volet and Wearden2001; Hamamouche & Cordes Reference Hamamouche and Cordes2019; Odic Reference Odic2018; Provasi et al. Reference Provasi, Rattat and Droit-Volet2011; vanMarle & Wynn Reference vanMarle and Wynn2006). Contradicting the proposed temporal updating system, I first describe non-symbolic timing as the most basic form of timing. In doing so, I also unveil infants and young children's impressive non-symbolic timing abilities.

Although I agree that the temporal reasoning system, which supports our mental representations of temporal symbols (linguistic labels, units of measurement, etc.), is not available until later in development, a substantial literature suggests that from birth we are able to represent time non-symbolically (Brannon et al. Reference Brannon, Suanda and Libertus2007; Odic Reference Odic2018; Provasi et al. Reference Provasi, Rattat and Droit-Volet2011; vanMarle & Wynn Reference vanMarle and Wynn2006). Our non-symbolic representations are very approximate and do not require any linguistic information. To test non-symbolic representations of time, participants are often asked to discriminate between two unique durations. For example, participants may decide which of two stimuli were displayed longer or which of two sounds lasted longer. To succeed in this task, participants should be tracking time. Other tasks, such as deciding whether a novel duration is more similar to a short or long standard duration (i.e., bisection tasks), also assess non-symbolic timing abilities (Church & Deluty Reference Church and Deluty1977; Meck & Church Reference Meck and Church1983). Given H&M's proposal, it is unclear how the dual perspective on timing would accommodate non-symbolic timing abilities. In particular, the proposed temporal updating system, which H&M describe as the most basic timing system, could not support performance on non-symbolic timing tasks. This is particularly noteworthy given that many researchers believe non-symbolic timing to be the most basic form of timing.

Moreover, according to H&M, infants and children under the age of 5, who are incapable of reasoning about time, should not succeed in non-symbolic timing tasks. Counter to H&M's proposal, however, young children are quite capable of making temporal judgments prior to the age of 5. For example, children as young as 3 show ordered performance on temporal bisection tasks. That is, as the duration increases, children become more likely to identify the novel duration as being more similar to the long standard duration (Droit-Volet & Wearden Reference Droit-Volet and Wearden2001). Relatedly, after learning a single standard duration (e.g., 4 seconds), 3-year olds are capable of discriminating the learned duration from a novel duration (e.g., 2 seconds [Droit-Volet et al. Reference Droit-Volet, Clement and Wearden2001]). Although children's non-symbolic timing abilities become more precise with age (Odic Reference Odic2018), these data indicate that young children are fully capable of making temporal judgments.

Even more impressive is research demonstrating infants’ ability to time non-symbolically (infants: Brannon et al. Reference Brannon, Suanda and Libertus2007; Provasi et al. Reference Provasi, Rattat and Droit-Volet2011; vanMarle & Wynn Reference vanMarle and Wynn2006; children: Droit-Volet & Wearden Reference Droit-Volet and Wearden2001; Odic Reference Odic2018). Using a bisection task, Provasi et al. (Reference Provasi, Rattat and Droit-Volet2011) discovered 4-month olds were capable of discriminating unique durations. First, infants heard a short sound (500 ms), followed by an image on the left side of the screen and a long sound (1,500 ms), followed by an image on the right side of the screen. In other words, infants were trained to look left when they heard the short duration and right when they heard a long duration. Then, during the test trials, infants heard intermediate durations (750 ms, 1,000 ms, 1,250 ms), and the direction of their first look was recorded, which the researchers interpreted as the infants’ indicating whether the duration was more similar to the short or long standard value. If infants were unable to detect differences in the durations, they should have looked equally to the left and right. Yet 4-month-olds showed a greater preference for the long standard duration as the duration increased. Using a different paradigm, Brannon et al. (Reference Brannon, Suanda and Libertus2007) also found infants were capable of non-symbolic timing. Here, infants were habituated to a cow opening its mouth for a certain duration. After the baby had habituated (was no longer interested in the cow's movement), the cow opened its mouth for a new duration. Again, if infants were unable to detect the change in duration, their looking time should stay consistent upon seeing the cow open its mouth for a novel duration. Contrary to this, 6-month olds’ looking time increased upon observing the cow's mouth opening for the novel duration, indicating that they noticed the change in duration. This finding has not only been replicated (vanMarle & Wynn Reference vanMarle and Wynn2006), but also extended to include changes in neural responses during timing tasks in both infants and adults (Brannon et al. Reference Brannon, Roussel, Meck and Woldorff2004; Reference Brannon, Libertus, Meck and Woldorff2008).

In sum, the proposed dual timing system neglects non-symbolic timing abilities, a process that would not be supported by H&M's temporal updating system. In doing so, the authors suggest that infants and children are incapable of representing time until the age of 5, when the temporal reasoning system becomes available. I contend, however, that the temporal updating system does not fully account for basic timing abilities and, therefore, unfairly discredits infants and children as well-tuned timers.