11.3.1 Baillargeon's Theory

Infant knowledge & reasoning of the physical world

• Baillargeon’s theory of infant knowledge and the physical world is a nativist explanation of early infant abilities
• Baillargeon assumed that infants have an inbuilt sense of object permanence, unlike Piaget, who thought that infants acquire object permanence around the age of eight months
• Baillargeon believed that infants are born with a ready-made sense of the physical world and that this does not have to be constructed using the ‘building blocks’ of experience
• This innate understanding of the physical world was termed the ‘physical reasoning system’ by Baillargeon (2012)
• Baillargeon argued that infants are born with a sense of object persistence i.e. that an object still exists even when it is occluded (blocked) by another object and so she devised a series of experiments to test this theory (see below)

Baillargeon used ‘impossible events’ to test object persistence in young babies

• Violation of expectation (VOE) refers to events which defy logic and do not appear to be physically possible
• VOE research depends upon an infant’s innate understanding of the physical world (e.g. If a dog walks behind a fence I can’t see the dog anymore)
• Baillargeon researched VOE by setting up a series of experiments in which an infant’s reaction to an impossible event was observed
• An impossible event is one which should not happen if objects/people/animals obey the laws of physics i.e. solid objects should not be visible if they are obscured by another solid object
• An example of one of Baillargeon’s procedure is as follows (Baillargeon & DeVos,1991):
  • Infants aged three months old were shown a series of objects (e.g. a carrot) which then moved behind a screen and then reappeared on the other side of the screen (the habituation phase)
  • The upper half of the screen had a window built into it (see the diagram above)
  • In the ‘possible’ condition the infant watched a short carrot move behind the screen i.e. the carrot moved out of sight as it was not tall enough to be seen through the window but they saw it again once it had gone beyond the screen
  • In the ‘impossible’ condition the infant watched a tall carrot move behind the screen i.e. the carrot should have been visible through the window but it did not appear again until it had gone beyond the screen
  • The infants showed much more interest, surprise and paid more attention when the impossible event occurred than in the possible event condition
  • Baillargeon concluded that the infants had expected the tall carrot to appear through the window and that this was evidence of object persistence in three month-old infants

Research which investigates Baillargeon’s theory

• Bower (1982) - An experiment in which infants’ heart rates were measured during a possible and impossible event: their heart rate increased when presented with an impossible event
• Wang et al. (2003) found, via two experiments, that 4 month-old infants show VOE in tasks involving hidden objects even without the usual habituation phase 
• Aguilar and Baillargeon (1999) -  Infants were habituated to the sight of a Minnie mouse toy being passed from one side of a screen to the other using a high window condition (possible event) and a low window condition (impossible event): infants stared at the low window condition more as predicted by VOE 

Evaluation of Baillargeon’s Theory

Strengths

• VOE is now a widely-used  technique in research on object permanence/persistence which means that Baillargeon’s theory is reliable
• There is a lack of evidence that understanding of the physical world (e.g. the law of gravity) is not universal hence Baillargeon’s theory could be said to cross cultures and apply to all human beings

Weaknesses

• Rivera et al. 1999 suggested that infants spend longer looking at an impossible event due to their preference for observing moving objects more than those that are stationary e.g. Baillargeon may have been biased when she reported her findings
• Using infants as participants is fraught with difficulties: it is almost impossible to truly understand a baby’s behaviour (the baby cannot be asked about their behavioural responses) so the results are open to interpretation

Link to Issues & Debates:

Baillargeon’s theory extends to pretty much all of humankind so it is nomothetic in its sweep (e.g. the idea that people are born with at least some understanding of the physical world). A nomothetic approach is useful to some extent as it helps to ‘join the dots’ of how humans as a species navigate their world but the downside of this is that it lacks insight into personal experience which could be achieved using an idiographic approach.