Experimental PsychologyPSY 433 Introduction
Thinking Like a Monkey • Jerry Adler, Smithsonian Magazine, January 2008 • Do monkeys assume that people act like monkeys? • Do monkeys have a “theory of mind” – the ability to impute thoughts and intentions to another individual? • How do you test what is going on in anyone’s head, much less a monkey’s mind?
Laurie Santos Assistant Professor of Psychology Yale University
Cayo Santiago • An island off the coast of Puerto Rico that is a sanctuary for rhesus monkeys.
Rhesus Monkeys • One of 22 species of Macaques (primates, ranging from Western Africa to Japan). • Widely used in lab research. • Young monkeys are typically used as subjects because the adults are dangerous and uncooperative. • This creates an artificial environment for studying social and cognitive behavior. • Free-ranging monkey colonies permit more natural behavior to emerge.
The Experiment • Hypothesis – If monkeys attribute monkey behavior to humans, they will treat humans similarly to monkeys. • The task – Food stealing and guarding behavior occurs because monkeys will steal unguarded food. • Place an unguarded grape in reach of a monkey and see if it will steal it when unguarded. • This works.
Theory of Mind • First, one person places two grapes in two 3-sided boxes and guards them. • Second, the first person turns away while a different person moves the grapes into two different boxes. • Third, the first person turns back and guards the two boxes that no longer have grapes. • Question: Will the monkeys recognize that the person is not guarding the moved grapes and attempt to steal them?
A B C Setup for the Task Person stands here to guard the grapes Grape Grape Monkey approaches here to steal the grapes
A B C Manipulation Person stands here to guard the grapes Grape Grape Monkey approaches here to steal the grapes
A More Difficult Test… • Never both turn your backs on the monkeys or they will rush the grapes. • Trial 1 – the monkey languidly scratches itself then turns and looks out over the rocks to the sea. • Trial 2 & 3 – no approach by the monkey. • Trial 4 – the boxes blow over. • Trial 5 – as soon as the grapes are displayed the monkey walks away.
What Happened... • Trial 6 – the monkey gets off its haunches and walks swiftly toward the experimenter. “Turn around” Santos calls. The student pivots, pulls herself up to full height and stares right at the monkey. It snarls menacingly back at her. She shrieks and runs to hide behind a colleague. The monkey grabs both grapes and runs away, chewing. • Conclusion – monkeys cannot make the mental leap to a concept of “false belief.”
What if it had Worked? • What would a successful outcome be? • The monkeys can see the grapes. • It appears as if all 3 boxes are being guarded. • There are 2 grapes, so a monkey without any knowledge has a 50-50 chance of picking either grape. • If the monkey understands that the person is unaware of the grape’s positions, then it should pick the moved grape (in a new location) more often than the other grape.
Critiques of the Study • Can monkeys select the moved grape more often for some other reason? • What were the experimenters wearing? • What else might the monkeys be thinking? • Is it a problem that so many monkeys are uninterested? • When the task is too difficult to do at all, are the results meaningful? • Perhaps a different task is needed.
Why We Do Research • Basic Research -- We may not care about monkeys but we care about theories of evolution and the innateness of human social behavior. • Applied Research -- We care about what works, and other practical questions. • Abstinence-only sex education
Does Abstinence Education Work? • Impacts of Four Title V, Section 510 Abstinence Education Programs, Final Report (April 2007), Mathematica Policy Research, Inc. • http://www.mathematica-mpr.com/publications/PDFs/impactabstinence.pdf • The goal of abstinence education is to encourage teens to abstain from sex outside marriage, thereby reducing teen pregnancies and STDs.
Study Design • Abstinence education has received $87.5 million in funding each year. • The Balanced Budget Act of 1997 authorized a scientific evaluation of abstinence education. • Teens in four programs were compared to control groups consisting of teens from the same locations offered no services. • All characteristics of the teens were the same except program participation.
Results • All graphs show no difference between controls and program participants. Tables show the following: • Program teens were significantly more likely than control teens to know that birth control pills do not prevent STDs. • Program teens were significantly less likely than control teens to know that condoms do prevent STDs. • Peer support is ineffective because social groups change across adolescence.