Daniel Willingham--Science & Education
Hypothesis non fingo
  • Home
  • About
  • Books
  • Articles
  • Op-eds
  • Videos
  • Learning Styles FAQ
  • Daniel Willingham: Science and Education Blog

Neurosci & Educ.--5 days, 5 ways. Day 4: Confirm a Construct

12/6/2012

 
This is Day 4 of my week-long series of posts on the use of neuroscientific data in educational practice. 

Links to previous posts:

Challenges in applying neuroscientific data to education.
Day 1: Basic architecture
Day 2: Single cell inspiration
Day 3: Reliable neuro-knowledge

Today I'll tackle what is probably the most common misinterpretation of human brain-imaging data.

It's almost irresistible to interpret brain imaging results as making visible  and thereby, confirming , some abstract construct you use to account for behavioral data. By abstract construct I mean some entity that you've invented that's meant to account for data. 
Picture
For example, suppose I notice if someone reads a phone number and then is distracted, he can remember the phone number for about 30 seconds or less. If he's distracted longer, the phone number is forgotten.

I suggest that there is a mental structure called a short-term memory system, which can store information for about 30 seconds. Short-term memory is an abstract construct; it's a proposed mechanism of the mind, which I think will help explain behavior.

Now it's clear that I've simply invented this idea of a short-term memory and that seems like a problem. "Oh people remember things for 30 seconds? That must mean you've got a remember-for-30-seconds mechanism in your mind!" I need something better to persuade people (and myself) that this entity actually helps explain how people think.

But now suppose I use functional brain imaging during that 30 seconds. I test 20 people and find that the same network of three brain areas is always active. Haven't I now seen short term memory in action? And doesn't this support my theory?

No and no.

Picture
To understand why not, suppose instead that I proposed a theory that there is a "cafeteria navigation" module in the brain whose sole purpose is to help you select items when you're in a cafeteria. And suppose I conduct an elaborate experiment where people wear virtual reality goggles and see a virtual cafeteria that they navigate while I image their brains. Lo and behold, there is a network of six brain areas that is active in every one of my subjects during this task! I've found the cafeteria navigation system! It must be real!

Here's the problem. Finding activation is not interesting because mental activity is going to cause brain activity somewhere. Some part of the brain is always going to "light up" during a task. It proves nothing.

A more reasonable interpretation of my cafeteria study is this: people have brain systems that support vision, decision making, movement, spatial processing, etc. When given a complex task (e.g., cafeteria navigation) they recruit the appropriate systems to get the job done. The "cafeteria navigation system" is a dumb theory because it applies to just one task.

How do we know what the real brain systems are then, if "finding" them via brain imaging doesn't work?

Well, if we think systems ought to support lots of different tasks, that's a clue. This is a general desideratum of science, not particular to psychology. It's okay to make up theoretical entities that can't be observed if they can account for a lot of data.

Picture
In the most famous example, Newton readily admitted that he didn't know what gravity was. And gravity was very peculiar: it was a force that purportedly had action between two objects instantaneously at great distances, with nothing intervening. Newton's reply was that, peculiar as the entity might be, it was a crucial part of a theory that accounted very well for an enormous amount of data.

Likewise, it's legitimate for me to propose something like "short term memory" if it's part of a theory that accounts for a lot of data. But the mere fact that some part of the brain is active during what I claim to be a task tapping short-term memory doesn't help my case. I need to show that "short term memory" helps to account for data.

So can brain imaging do anything to help verify that a theoretical construct is useful? Yes. It can serve as a dependent measure.

Here's a problem I face in persuading you that my proposed construct, short-term memory, is legitimate. I need to show that short-term memory participates in lots of tasks (so its not like the cafeteria navigation task). But how do I know that short term memory is at work during a task? Presumably there would be some sign in your behavior that it's at work. But in addition, if I've previously shown that three brain areas, A, B, and C, support short-term memory, then A, B, and C ought to be active during any task that requires short-term memory. Now I have a way of verifying that short-term memory contributes to a task, and that's useful to me, because one of my goals is to show that it's important in many different tasks.

Further, I can use this fact (A, B, and C will be active) to show that my theory of short-term memory is well developed. I can devise two tasks that look very very similar, but that I (with my terrific theory in hand) can predict differ in the extent to which they tap short-term memory. So one task will make the three areas active and the other task won't even though the tasks look very similar. Or I can devise two tasks that look wildly different but that my theory predicts both tap short-term memory and so will show overlapping activation in areas A, B, and C.

Tomorrow: A highly practical application, and the big wrap-up.

Jason Millard
12/5/2012 10:55:43 pm

Great outline Dan. Flows nicely from your book.

I have a few questions, however:

1. Are there fMRI data that supports WM deficits along with processing speed in reading (pre-frontal cortex regions)?

2. Mental Illness is increasingly being supported/refuted as having biological markers and definitive changes in structural brain regions (depression - axis 1; borderline & bipolar - axis 2) does what you're saying undermine such assertions by people such as John Gunderson at Harvard and others using fMRI studies to support behavioral observations/characteristics?

Best,

Jason

Sherwood
12/6/2012 05:31:44 am

Regarding Part 4: Good science here on the nature of evidence. Not clear to me how it applies to education.


Comments are closed.

    Enter your email address:

    Delivered by FeedBurner

    RSS Feed


    Purpose

    The goal of this blog is to provide pointers to scientific findings that are applicable to education that I think ought to receive more attention.

    Archives

    July 2020
    May 2020
    March 2020
    February 2020
    December 2019
    October 2019
    April 2019
    March 2019
    January 2019
    October 2018
    September 2018
    August 2018
    June 2018
    March 2018
    February 2018
    November 2017
    October 2017
    September 2017
    August 2017
    July 2017
    June 2017
    April 2017
    March 2017
    February 2017
    November 2016
    September 2016
    August 2016
    July 2016
    June 2016
    May 2016
    April 2016
    December 2015
    July 2015
    April 2015
    March 2015
    January 2015
    September 2014
    August 2014
    July 2014
    June 2014
    May 2014
    April 2014
    March 2014
    February 2014
    January 2014
    December 2013
    November 2013
    October 2013
    September 2013
    August 2013
    July 2013
    June 2013
    May 2013
    April 2013
    March 2013
    February 2013
    January 2013
    December 2012
    November 2012
    October 2012
    September 2012
    August 2012
    July 2012
    June 2012
    May 2012
    April 2012
    March 2012
    February 2012

    Categories

    All
    21st Century Skills
    Academic Achievement
    Academic Achievement
    Achievement Gap
    Adhd
    Aera
    Animal Subjects
    Attention
    Book Review
    Charter Schools
    Child Development
    Classroom Time
    College
    Consciousness
    Curriculum
    Data Trustworthiness
    Education Schools
    Emotion
    Equality
    Exercise
    Expertise
    Forfun
    Gaming
    Gender
    Grades
    Higher Ed
    Homework
    Instructional Materials
    Intelligence
    International Comparisons
    Interventions
    Low Achievement
    Math
    Memory
    Meta Analysis
    Meta-analysis
    Metacognition
    Morality
    Motor Skill
    Multitasking
    Music
    Neuroscience
    Obituaries
    Parents
    Perception
    Phonological Awareness
    Plagiarism
    Politics
    Poverty
    Preschool
    Principals
    Prior Knowledge
    Problem-solving
    Reading
    Research
    Science
    Self-concept
    Self Control
    Self-control
    Sleep
    Socioeconomic Status
    Spatial Skills
    Standardized Tests
    Stereotypes
    Stress
    Teacher Evaluation
    Teaching
    Technology
    Value-added
    Vocabulary
    Working Memory