A Comprehension of Infants' Tool Use

An ability to use a tool in human infants was found at different age, due to the nature of individual differences or causal cognition. However, significant evidence indicates that infants appeared to start and master their knowledge regards tool using, at the period of 8 to 24 months, the sensorimotor stage 4 to 6 (Piaget, 1952; McCarty, Clifton, & Collard, 2001).

The mechanism which drives infants to play with objects or to explore their body is believed to be the case of intrinsic motivations (Ryan & Deci, 2000), and the benefit that play gives to the infants is the acquiring of knowledge about their body and the world. This is a cyclical process, in which motivation drives action, actions cause changing in the infants' perceptual space and those changes will, for example, trigger the motivations such as fun or surprise. There are at least two different views with regards to a motivation system. The first view is a motivation as rewarding scheme (Oudeyer & Kaplan, 2007). This is done by considering that there are critics inside and outside of an agent which generate rewards. If the critic acts outside the agent, this will

be called extrinsic motivation. In contrast, if the critic is inside the agent, the reward is considered as self-generated. This is an intrinsic motivation system. The second view is a motivation as a driving force (Schlesinger, 2013). There is no critic in this scheme. The rewards are determined by the agent itself. This motivation can be viewed as neural activation which is kept on activating when preferred situation occurred, and will be depressed when nothing interesting happens or practiced actions have been mastered.

Schlesinger and Langer (1999) pointed to important evidence regarding infants' developing tool use actions and expectation. Infants exhibit tool use behaviours at an early age and these actions develop through developmental stages from subjective to objective (subjective, transitional and objective). When an infant was in the subjective state of tool use, it cannot solve a given tool use problem due to the lack of required action (i.e., pulling). Because, this is a beginning stage, the pulling action has not developed yet. Infants at this stage may instead play with the tool, or ignore it and try to reach for the toy with their hands. The second stage is transitional. At this stage infants can use the tool to retrieve the goal object but they exhibit the same action in both cases of tool use events (i.e., contact or noncontact). Therefore, it seems likely that a spatial relation between the tool and goal object does not affect the infants' action selection. Finally, infants at the objective stage solve the tool use problem properly. They can shift to use other strategies (e.g., offer the tool to the experimenter) if they do not know how to retrieve the toy in the case of non-contact. These three stages of tool use actions reflect individual difference in infants' tool use performance. In addition to tool use actions, infants also observe the outcome of a currently perform action through visual perception. These processes, later, can be used to form an ability of expectation. The infants can distinguish the difference between possible and impossible tool use events through the practice of this observation. This study restricted tool use problem to relying

only on pulling action, but put more focus on the infants' expectation on the tool use events. It used two types of tool use problems including supporting and surrounding. The case of supporting refers to the use of a rectangular cloth as tool. The case of surrounding was a hook that used as tool to retrieve the object. The different in the tasks that used cloth or hook, can be determined easily by the infant due to the big different in their appearance. The evidence shows that, at an early age, infants spontaneously pull tablecloths, blankets in order to reach a goal object. Therefore, it is possible to claim that supporting tool use actions are developed before surrounding. The expectation of actions outcome can be viewed as the use of mental imagery in young infants.

The problem of tool use in human infants during the period from 8 to 24 months is highly dependant on the condition of spatial gap between the tool and toy. All infant participants can succeed in the retrieving when the tool and the toy are connected (Rat- Fischer et al., 2012). The point is that only older infants can achieve the case of large spatial gap. As suggested by psychologists, the full understanding of how to use tool starts at the age around 18 months.

In the experiment on infants' tool use development conducted by Rat-Fischer et al. (2012), infants aged 14 to 22 months were tasked to retrieve an out-of-reach toy put on a table using a provided rake-like tool. The aim of this study is to examine how tool use understandings in infants develop with age. The authors suggested that the infants start to have this knowledge on reaching 18 months of age. The key difficulty in this kind of tool use is the spatial relation between the tool and the toy. All infants can successfully retrieve the toy and the tool when they are physically connected. The success rate varied when the spatial gap between the two objects increased. However, in this study, only the condition of large spatial gap, tool in hand, that truly reflect the understanding of tool use in infants. In addition, by providing a demonstration session to infants that fail to

solve the task, the infants can benefit from the demonstration indicated by the spontaneous success on a further test, but this happen only in the infants aged 18 months and older. This suggests that observation of a tool use demonstration can fulfil the sensorimotor experience of the infants, but it appears that this benefit only happens when the infant has initial knowledge of how to use tool. It is worth noting that at the age of older than 24 months, the infants have no problem in solving a tool use task with large spatial gap.

In Lockman (2000), banging movements or instrumental hammering produced by infants during the second half year of age are interpreted as practice of the actions they have learnt, in order to initially distract their perception, effect their world, and drive sensorimotor learning. In this view, tool use is possible through the processes of perception-action routines. A tool causes change to a contact object and the infants use this to explore their environment.