Theory and Debate in Developmental Psychology

Christopher Maymon

Victoria University of Wellington

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Lecture Objectives

  1. A glimpse into a specific contemporary issue in cognitive developmental psychology (Theory of Mind)

  2. Kinds of puzzles that motivate creation of new theories

  3. How theories are challenged (or supported) by new evidence

  4. How competing theorists challenge one another’s arguments

Theory of Mind (ToM)

  • also known as ‘Mindreading’ (but not in a ‘mystical’ sense)

  • We all are operating on a theory that each of us developed:

    • The theory: other people have minds, and their mind explains their behaviour

  • It is only a theory because we can never prove it

    • Cannot directly observe a mind

    • Can only infer that a mind exists based on observing patterns of behaviour

  • Having/Using our ToM requires representing other people’s mental states (knowledge/beliefs)

    • A highly adaptive cognitive ability (essential for both cooperation & competition)

    • Also very abstract (how do we represent in our mind what somebody else knows or believes?)

    • Therefore, it is likely that everyone develops a ToM, but it probably takes a long time because it is so abstract.

1983

Wimmer & Perner

  • Sally Anne Task - False Belief (FB) Task

  • Findings: 3 year olds answer incorrectly. 4 year olds answer correctly

  • Conclusion: Conceptual change takes place around 4 years of age!

2005

Onishi & Baillargeon

  • Violation of Expectation (VoE) task

  • Findings: 15 months look longer when person’s behaviour is not in line with their false belief

  • Conclusion: Infants use their ToM to predict the person’s behaviour & are surprised if the person’s acts based on information that only the infant has seen!

The Puzzle

  • One set of findings: Theory of Mind emerges around 4-years (48 months)

  • Another set of findings: Theory of Mind has emerged by 15-months.

  • How do we reconcile these findings??

How can we solve the puzzle?

  • Perhaps one of these findings is true, and the other is false?

  • How could we know which is true and which is false?

Criticizing the inferences drawn from infants’ looking time

Ted Ruffman (University of Otago)
  • Ted Ruffman says “I can explain these findings (Onishi & Baillargeon’s) without requiring the use of Theory of Mind (or any similarly sophisticated reasoning)!”

Behaviour Rules

  • Behaviour Rules: Infants aren’t making predictions based on representing other peoples’ minds! They are making predictions based only on having observed similar behaviour in other people.

    • You don’t need to know why someone is behaving in a certain way, in order to make a prediction that they will behave in that way.

  • Why is this a challenge to Onishi & Baillargeon’s view?

The Law of Parsimony

  • Law of Parsimony: A scientific principle that when you are faced with two competing explanations for a pattern of results, the explanation that requires the fewest assumptions (or, the simplest explanation) is more likely to be correct.

  • Behaviour Rules are a simpler explanation of infants’ behaviour than the explanation that they are representing another person’s mind (more complex).

Rose Scott (Renee Baillargeon’s student) enters the ring!

Rose Scott (University of California Merced) Student of Renee Baillargeon

  • Rose Scott says: “the behaviour rules account can only make post hoc explanations!”

    • Behaviour rules can explain any set of findings, as long as the subjects could have observed similar behaviour in the past!

Behaviour Rules under fire!

  • Why is it a problem that behaviour rules only makes post hoc explanations?

    • It means that the Behaviour Rules explanation is an Un-falsifiable Theory

  • Why are Un-falsifiable theories a problem?

    • For a theory to taken seriously by scientific community, it needs to make testable claims (i.e., hypotheses that can be demonstrated using the scientific method).

    • If a theory is “un-falsifiable” the theory does not make testable claims; i.e., the theory cannot be demonstrated empirically.

    • This does not mean that the theory is true. It just means that if the theory is false, science cannot tell us that it is false! We cannot know one way or the other!

2007 - A new dependent measure for infants: Anticipatory Looking

Victoria Southgate (Birkbeck University of London)

Southgate, Senju, & Csibra

  • There are other ways people’s expectations are revealed through eye movements!

  • If we expect something to happen at a specific location, we will move our eyes to that location in anticipation of the outcome

    • This gave rise to what is known as the Anticipatory Looking paradigm!

Anticipatory Looking

Anticipatory Looking - Results

  • Two Measures of anticipatory looking: Where do infants look first & how long do they look at each box.

  • 17 (out of 20) infants looked first at the correct box in the false belief conditions! (i.e., where the person thinks the object is)

  • Infants spent ~2x as long looking at correct box (M = 965 ms) compared to incorrect box (M = 496 ms)

  • Conclusion: Infants predict how people will act when they know that person has a false belief!

What now?

  • Huge support for the view that infants have a ToM!

  • Why?

    • Converging evidence: if a theory is true, then it would be expected that different sources of evidence would be able to independently show support for the theory

    • VoE and Anticipatory looking show that infants can predict behaviour of person with false belief

  • Behaviour Rules can explain Anticipatory Looking equally well (but as Rose Scott said, we could never know if behaviour rules are true or false!)

  • The new question: How is it possible that infants are able to represent other people’s minds at such a young age, and yet cannot use language to demonstrate that understanding until they are 4-years-old?

2009

  • Ian Apperly & Stephen Butterfill propose a Two-Systems Theory of human mindreading

  • There are two different cognitive systems for reading minds

  • Patterns of looking are driven by one system

  • Verbal responses are driven by the other system

Ian Apperly (University of Birmingham)

Stephen Butterfill (University of Warwick)

The Two Systems for Mindreading

System 1:

  • Efficient

  • Develops very early in life (infancy)

  • More automatic (we don’t know we’re doing it, we don’t need to try)

  • Very Simple

System 2:

  • Flexible (sophisticated)

  • Develops later in life (~4th birthday)

  • Not automatic (requires effort)

  • Can understand complex social situations

    • Example: “I know that he knows that she know that I saw what he did”

The Argument for Two-Systems for Mindreading

  • Any ‘two systems’ account (of which there are many in psychology) must provide a compelling argument that there is very good reason why one system would not suffice

    • Brains do not evolve to create multiple specialized systems unless there is very good reason to do so!

  • Apperly & Butterfill’s Argument:

    • Mentally representing a persons’s mind (intentions, beliefs) is an abstract mental task

    • And representing abstract concepts is cognitively demanding

    • And concepts that are cognitively demanding tend to take longer to process

    • And we are more likely to make errors about concepts that are cognitively demanding

    • Therefore, if it likely that throughout human evolution (millions of years) people were less likely to survive due to failing to represent other minds fast enough (or made errors), then it stands to reason that there is indeed a selective pressure that could necessitate the evolution of a simpler cognitive system for representing other people’s minds

Two Systems: Empirical Hypotheses

  • Unlike the behaviour rules account, the two-systems theory does generate empirical (testable) hypotheses!

  • The efficient system can be measured using eye movements and the flexible system can be measured using verbal responses

  • For System 1 to be an ‘efficient’ system, it needs to be quite simple/rudimentary

    • Therefore, it must be the case that the efficient system will reliably make errors that the flexible system does not!

    • Prediction: eye movements and verbal responses will both be correct on simple false belief tasks, but on more difficult false belief task, verbal responses will still be correct but eye movements will be incorrect!

2013

Jason Low (Victoria University of Wellington)

Low & Watts

  • If two-systems account is true, then there should be situations where the efficient system will be wrong but the flexible system will be right

  • In other words, the efficient system will show signature limits

  • Tested 3-year-olds, 4-year-olds and adults

    • Measured anticipatory looking behaviour & verbal responses

  • Reasoned that efficient system can process false beliefs about an object’s location (i.e., person will look where they last saw the object) BUT will not be able to process false belief about object’s identity (She thinks that the toy is red and not blue, but it is acutally red and blue).

Low & Watts: Procedure

Low & Watts: Findings

  • all age groups look to the correct box in false belief location task

  • When asked where the agent will look, we see the same developmental trajectory for both kinds of tasks (false belief about location + false belief about identity)!

  • BUT all of the age groups make incorrect anticipatory looks in the false belief identity task!

  • Therefore, Signature Limits!

Final remarks

  • This is a simplistic version of an even more complex story that is still ongoing

  • Future work needs to find other examples where there are signature limits (and across other sources of data: converging evidence)

  • Scientists aren’t just doing research that interests them; they are responding to the theories and evidence of other scientists, trying to create clever/strong tests that could settle the debate

  • If these debates and research sound exciting to you, you may be a cognitive scientist, talk to your doctor if becoming a cognitive scientist is right for you

Nga mihi nui