Object Knowledge in Infants Flashcards
(35 cards)
What is developmental psychology?
Seeks to understand change over time and the underlying mechanisms for this change.
What are the different key stages and ages in development?
Infant - 0-18 month old; can’t talk.
Toddler: 1-3 years; can walk.
4-6 month old; can sit up and has started reaching and grabbing.
6 months - head turning response.
What is object knowledge?
Infants have to process and understand a large amount of sensory information from birth.
The same object presented from different perspectives and angles can appear different.
Retinal image size varies but object size/ image size is constant. Objects have the property of size constancy.
An object continues to exist in its whole when it is occluded partially or is out of site.
What are the challenges to measuring infant’s responses?
Can’t speak and this language barrier means that conclusions from recordings and observations are inferential.
Need to establish empirical, non-verbal evidence for knowledge acquisition in infancy.
Can only infer basic things like ability to discriminate or surprise.
Must be reliable (repeatable results) and valid (close to the truth).
What are the classic methods for testing infant development?
reaching behaviour
preferential looking
habituation
violation of expectancy
How can child development be studied by measuring reaching behaviour?
Used by Piaget to indicate object knowledge.
Requires a level of working memory capacity that may be too demanding for infants
Even when fully attentive infants have more profound memory limitations than adults which could explain the absence of reaching behaviour and can confuse and mislead conclusions.
Must retain spatial information for a period of time long enough to execute action.
The longer the delay the worse performance. Again issue of memory and coordination not knowledge of the world.
Action and motor skills are distinct from cognition
How can child development be studied by measuring looking preference?
Present infants with two different stimuli and measure whether they look consistently longer at one over the other
Choosing to look at one thing more than another is evidence that the infant is able to discriminate.
Important that other things are controlled or counterbalanced over trials
How can habituation be used to measure infant’s responses?
A stimulus is presented repeatedly until the infant stops being interested in it.
An infant becoming bored and losing attention is evidence that they remember the stimuli.
Once the infant has been habituated they can be shown a new stimulus.
If they look at the new stimulus this is further evidence of discrimination.
E.g infants are shown either a set of obtuse or acute angles with stimulus orientation varied across presentation so that they only constant feature is the angular relationship. They are then tested for a novelty preference between acute and obtuse angles.
Cannot conclude anything from null effects.
An infant looking at two stimuli equally means that we cannot conclude or infer anything.
If an infant habituates this is evidence of early emergence sensory registration and visual memory.
Some psychologists argue that infants’ looking preferences reflect competing preferences for novelty and familiarity. When fully familiarised infants prefer novel stimuli, but when they are not fully familiarised, infants prefer familiar stimuli.
Lack of distinct criteria against which the extent of habituation can be measured.
Can’t conclude whether looking time is the result of novelty, familiarity or even a priori preferences.
What is the violation of expectancy paradigm?
This technique is similar to habituation.
Infants are familiarised with an event sequence and then presented with two novel event trials.
One possible event, based on properties of objects and one impossible event that breaks the laws of physics.
If an infant looks longer at the impossible event, this suggests that they understand it violates reality.
What methodological advances have been made in developmental psychology?
Modern Technology
Eye-tracking
Neuroimaging methods
Computational methods
Methodological Advances
Original experiments use cameras and research assistance coding the direction of looks and timing with a stopwatch
Often done independently by two people blind to experimental conditions to check inter rater reliability.
But human observers are not particularly sensitive.
Therefore the measurements done in early studies are subject to human error.
Inadequate levels of precision for reliable and valid conclusions.
Eye tracker technology provides a finer measure of where exactly children are looking and for how long, which provides spatial and temporal characteristic data.
Because of the specificity of the measurement, more robust inferences can be made with confidence.
Visual preference should be regarded as an effective alternative to verbal expression in infant studies especially when facilitated by the use of precise measurements.
What is object permanence?
The ability to understand that even if an object is no longer visible, it continues to exist.
What did Piaget believe about infant’s construction of knowledge?
Believed that children contact all knowledge through their interactions with the environment.
Initially these behaviours are based on built in behaviours like looking, sucking and moving.
Believed that perception alone is not sufficient for infants to understand their environment.
Action and interaction with the environment is necessary.
Children assimilate new information and accommodate their knowledge.
Argued for radical, qualitatively different stages of development.
What object knowledge did Piaget believe infant’s had?
Infants have no idea of themselves as independent entities in the world.
By 6 months (stage 1 and 2) they have worked out the difference between themselves and objects in the environment
They do not understand that objects have continuous and independent existence.
They think that objects’ existence is dependent on their own actions.
Throughout the first 18 months, infants have an imperfect understanding of the continued existence of any object, once it disappears from sight.
During this time, infants’ reactions to hidden objects reveal a gradual development, indicating the process of construction of knowledge (stages 3-5).
We can learn about this process through observing the errors infants make.
What is the stage 3 error?
6-9 months olds fail to search for a completely hidden object
However they will retrieve a partially hidden object
Towards the end of the stage 3 period they will search for a totally covered object if they happen to be moving towards it at the moment it was covered.
From this Piaget concluded that, at this stage, infants do not understand that the covered object still exists.
Even when they retried a partially covered object they think that their own movements have reconstituted the missing bits.
What is the A not B error?
9 month olds begin to retrieve objects which they see covered.
If a toy is put in place A and covered and retrieved but then moved to place B, infants tend to look for it in the original location.
This continues to about 12 months and even older if a delay is imposed.
From this Piaget concluded that the infant understand the object as the thing of the place
They think that moving their hand to the original place recreates the object.
Although they look for the object they do not understand that the object exists when hidden and therefore exists independently of their actions.
For infants an object’s existence is defined by the infant’s own actions rather than true object knowledge.
How has Piaget since been criticised?
The observations of these errors are reliable and well-replicated
However his interpretation and theory has been criticised by more recent evidence.
An important issue is Piaget’s reliance on action and motor skills to measure cognition.
If motor demands are removed, greater object knowledge is revealed at an early stage.
This is in line with Kellman and Spelke’s (1983) looking behaviour experiments which suggest that children have quite advanced object knowledge as early on as 2-4 months.
They seem to already have mental representations of objects but are not able to manipulate or explore objects.
This suggests that action is not leading to their object knowledge.
What was Baillargeon et al.’s (1985) Drawbridge experiment?
Habituation phase: 5 month olds (Piaget’s stage 3) are shown a drawbridge being rotated 180’
In the trials the infants are shown that there is a block behind the drawbridge.
Possible event: the drawbridge rotates 120’ and stops where it would have collided with the block.
Impossible event: the drawbridge rotates through 180’
Results: infants looked longer at the impossible event.
This suggests that 5 month olds have knowledge of object permanence because they expect that the block will continue to exist when hidden from view.
Moreover they know that one object can impede another as solid objects cannot pass through each other.
Control experiment where the box was placed next to the screen supports this interpretation
What was concluded from the Drawbridge experiements?
New methods of testing babies knowledge using preferential looking and habituation mean that we now know babies have knowledge of objects much earlier than Piaget claimed.
5 month olds would fail the stage 3 tasks in Piagetian experiments
Contrary to Piaget’s (1954) claims, infants as young as 5 months understand that objects continue to exist when occluded
However caution must be taken in interpreting looking time data as the impossible and possible events are two different perceptual events and experiences.
It is important to make sure that the difference in looking behaviour is driven by object permanence rather than a more basic difference at play.
Further experiments suggest that 3 month olds have object knowledge of object permanence
Need to explain why babies show failure of object knowledge in stage 4 but exhibit this looking behaviour.
How have the Drawbridge experiments been criticised?
Looking paradigms investigate perception not reasoning.
It is impossible to generate perceptually identical but conceptually distinct stimuli for habituation experiments (Haith, 1998)
Possible that difference in looking to expected and unexpected outcomes result from basic perceptual preferences rather than a deeper understanding.
Rivera et al. (1999) criticise the drawbridge experiments arguing that the 180’ event takes longer and therefore presents the opportunity for greater looking which would also account for the longer looking time at the impossible event condition.
Repeated the experiment without the hidden object and found that there was more looking towards the 180’ event and that looking times were comparable ot the occlusion events in the original drawbridge paradigm
However other work with appropriate controls suggests that the Drawbridge findings are still valid
Perceptual interpretations may account for some violation of expectancy findings but other findings are much more difficult to reconcile with simple alternatives.
What was Baillergeon’s (1991) Truck experiment?
Habituation event: experimenter places a black occluding screen on a stage next to a ramp and then rolls a truck down the ramp and then removes the screen to show that the truck stopped at the grey wall
Test condition: a red wall is placed in the path of the truck between the ramp and the wall
Possible event: occluder screen is lowered, truck is released and rolls down, screen is lifted and the truck has stopped at the red wall.
Impossible event: occluder screen is lowered, truck is released and rolls down, screen is lifted and the truck has stopped at the grey wall implying it passed through the red wall.
Recorded the infants looking at the outcome for 10 seconds, excluding infants who did not look for at least 2 seconds.
Infants looked significantly longer at the impossible event, in which the car passed through the wall than when it did not.
These events are perceptually very similar
What did Kellman and Spelke’s (1983) object perception studies find?
Habituation phase: presented with the same box moving with a pen moving behind it repeatedly.
Adult perceptual system fills in the invisible parts so that we perceive a partially hidden rod.
Test phase: presented with a broken rod and a complete rod.
Results: 4 month-olds look longer at the separate parts suggesting that these are perceived as new stimuli. This suggests that they do understand occlusion.
What did Slater et al. (1990) discover about knowledge of occlusion in newborns?
Newborns look longer at the complete rod.
This suggests that they interpret the stimulus literally and do not make perceptual inferences.
Joint movement of parts does not convey object unity to them.
The principle of common motion is key for infants to perceive object unity.
Results are only repeatable if the rod moves otherwise even 4 month olds show no spontaneous preference for either rid
What did Johnsons and Aslin’s (1995) variation on the occlusion studies find?
2 month olds display a pattern like the 4 month olds but not an identical one.
They fail direct replications of Kellman & Spelke but can pass with modified presentations.
2 month olds need additional information to express perception of object unity
If a narrower box is used that covers 26% of the rod compared with the original 41% or if there are small gaps in the box so that the rod is partially but never fully visible, they will pass.
Suggests perceptual learning over the first few months of life may underlie the rapid emergence of sensitivity to occlusion
What did Valenze and Bulf ‘s (2011) find about object knowledge in neonates?
Presenting stimuli tachistoscopically (continuous motion is represented by a series of distinct images due to flashing light) newborns looking preference will indicate object unity.
However these conditions are highly artificial so must be cautious about inferring genuine knowledge of object unity in the real world.
Does suggest that object unity is innate and understanding of such principles will gradually emerge through experience.
