Transcript What is Evolutionary Psychology?

Evolutionary Psychology, Workshop 2.
Domain-Specific Reasoning.
Aims of the Workshop.
 1. To critically review evidence concerning domain-specific
reasoning as measured by performance on selection tasks.
 2. To assess domain specificity from data obtained using
different versions of the Wason Task.
 Prior to this session you were asked to present 4
participants with 2 versions of the Wason task.
 We will firstly review domain-specificity as assessed by
performance on selection tasks, and relate our findings to
this evidence.
Domain-Specific Reasoning.
 The Standard Social Science Model assumes that the brain
contains content-independent, general-purpose reasoning
devices.
 If this is so, then we should solve different
logical
reasoning problems in the same manner, with the same
success.
 This is not so.
 When reasoning tasks involve spotting someone cheating
on a social contract performance is improved.
 Evolutionary psychologists thus argue that the brain is
modular, i.e. consists of content-dependent, domainspecific reasoning devices.
Neuropsychological Evidence.
 Evidence for such domain-specific reasoning has so far
come from performance on logic problems and thus lacks
ecological validity.
 However, Stone et al., (2002) recently reported the case of
RM who had suffered extensive brain damage affecting the
orbitofrontal cortex, anterior temporal cortex and the
amygdala.
 While he performed normally on Wason-type logic
problems, when the problem involved the violation of a
social contract he was impaired.
 This provides neurological evidence that reasoning about
social exchange can be selectively impaired.
Standard Version of the ‘Wason Task’
 Indicate only the card(s) you definitely need to turn over to
see if the documents of any of these people violate the
following rule.
 ‘If a student is rated ‘D’, then their documents must be
marked with a ‘3’.
D
P
F
Not-P
3
Q
7
Not-Q
Correct answer: D & 7 (P and not-Q).
Performance is poor on this version
Wason Task, Social Contract
 You are serving behind the bar of a city centre pub and will
lose your job unless you enforce the following rule:
 ‘If a person is drinking beer, then they must be over 18
years old’.
 Indicate only the card(s) you definitely need to turn over to
see if any of these people are breaking this rule.
Drinking
Beer
Drinking
Coke
25
years old
16 years
old
P
Not-P
Q
Not-Q
Correct answer: Drinking beer and 16 years old & 7 (P
and not-Q). Performance improves in this ‘social
contract’ version
Other Explanations.
 However, suppose that we have general-purpose reasoning
skills whose design makes us more likely to produce
logically-correct answers for familiar thematic rules?
 ‘Availability Theory’ suggests that a person’s past
experiences create associational links between terms
mentioned in tasks of logical reasoning.
 Thus, the more familiar the problem the better the
performance.
 ‘Social contract theory’ (Cosmides & Tooby, 1992) however
suggests that familiarity with a situation will have no
influence on performance.
 Cosmides (1989) tested both theories using familiar and
unfamiliar situations:
Comparisons Between Predictions.
‘Clear-Thinking’.
 Perhaps the content of social contracts simply facilitates
logical reasoning and is not to do with domain-specific
reasoning.
 We can test this by using switched social contracts i.e. by
presenting Wason-type problems with the logical argument
switched around.
 ‘Clear-thinking’ theory predicts that performance will be
uniformly bad on these more difficult tasks.
 ‘Social Contract theory’ predicts that changing the
argument will have no effect on a social contract problem.
 Cosmides (1989) showed that again social contract theory
predictions were supported.
Comparisons Between Predictions
Perspective and Reasoning.
 In all social exchange situations we can play two roles, e.g.
as an employer providing a pension to an employee.
 From the employer’s perspective, cheating is when an
overtime bonus is paid out but the employee did not
actually work the shift.
 From the employees perspective, cheating is when they
have worked the overtime shift but do not get paid the
bonus.
 Gigarenzer & Hug (1992) showed that when presented
with perspective change situations, results are as predicted
by evolutionary theory.
Gigarenzer & Hug (1992) Results.
Alternative Viewpoints.
 Shapiro & Epstein (1998) do not agree with domain
specificity, they argue that there is a single cognitive system
containing several generalised rules that can solve any
number of complex problems. E.g. a screwdriver:
 “Tightening screws requires turning them to the right.
Loosening screws requires turning them to the left. Because
what counts as success or error differs between the two
tasks, there must be at least two different kinds of
screwdrivers – one for tightening screws and one for
loosening them”.
 Sperber et al., (1995) argued that reasoning is not involved
at all in the selection tasks, instead people solve them by
judging the relevance of the information presented.
The ‘Rossi/Bianchi’ problem
 The City Council of Padua has asked for volunteers to take
care of visiting English schoolchildren. Volunteers have to
fill in a card, Mr Rossi and Mrs Bianchi are about to sort the
cards. Mrs Bianchi argues that only women will volunteer.
Mr Rossi says she is wrong, and states that males do
volunteer. Mrs Bianchi counters that if that is the case, the
males will be married.
 Which cards must you turn over to see if the following is
true - if a volunteer is male, then he is married
Relevant version
Male
Female
Married
Unmarried
Answer = ‘male’ and ‘unmarried’
‘Rossi/Bianchi’ Version 2
 In this version, Mrs Bianchi states that men with dark hair
love children and will thus volunteer.
 Mr Rossi says she is wrong, and asks her to prove it.
 Cards filled in by the volunteers show sex on one side and
hair colour on the other.
 Which cards must you turn over to see if the following is
true - if a volunteer is male, then he has dark hair.
Irrelevant version
Male
Female
Dark hair
Fair hair
Answer = ‘male’ and ‘fair hair’
Sperber et al., (1995) Results.
 36 students at the University of Padua were randomly
assigned to either version 1 or version 2.
 Both versions are logically and semantically similar.
 65% of the students gave the correct answer to version 1.
 Only 16% gave the correct answer for version 2.
 Sperber and colleagues argued that the most important
feature of this type of task is relevance - marital status is
often relevant to looking after children, whereas hair colour
is not.
 Neither version involves any form of deception or cheater
detection, casting doubt on Cosmides & Tooby’s (1992)
claims of a specific cheat-detection module.
Our Data (N=241).
% selecting
‘P’ and not-Q
Standard
Social Contract
Relevant
Irrelevant
Version
Version
Version
Version
9.1%
84.6%
31.9%
25.3%
Cheng & Holyoak (1989).
 They also disagreed with evidence presented by Cosmides
(1989) concerning performance on the Wason task.
 They pointed out that her versions of the task did not really
deal with social exchanges or social contracts.
 They gave different versions of the Wason task - none of
which involved social exchange or the identification of
cheaters, and correct performance was around 95%.
 The context of the Wason task - i.e. the explanation given
first, is crucial to how people perform.
 They concluded that evidence from the Wason task
provides no support for the natural selection of human
reasoning abilities.
Websites.
 For the remainder of the session I would like to locate some
web-based resources for evolutionary psychology.
 Firstly find the ‘Primer of Evolutionary Psychology’ written
by Tooby & Cosmides at:
 http://www.psych.ucsb.edu/research/cep
 Next have a look at the Frequently Asked Questions about
evolutionary psychology at:
 http://www.anth/ucsb.edu/projects/human/evpsychfaq.h
tml
 Finally, in the University electronic journals find the journal
‘evolution and human behaviour’ and have a skim through
recent editions.
References.
 Cheng, P.W., & Holyoak, K.J. (1989). On the natural
selection of reasoning theories. Cognition, 33: 285-313.
 Cosmides, L. (1989). The logic of social exchange: has
natural selection shaped how humans reason? Studies with
the Wason selection task. Cognition, 31: 187-276.
 Cosmides, L., & Tooby, J. (1992). Cognitive adaptations for
social exchange. In J.H.Barkow, L.Cosmides & J.Tooby, The
Adapted Mind, chapter 3, pp163-228.
 Shapiro, L., & Epstein, W. (1998). Evolutionary theory
meets cognitive psychology: a more selective perspective.
Mind and Language, 13: 171-194.
 Sperber, D., Cara, F., & Girotto, V. (1995). Relevance theory
explains the selection task. Cognition, 57: 31-95.