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, domain-specific 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’.

FD 3 7

Correct answer: D & 7 (P and not-Q).

Performance is poor on this version

P Not-QQNot-P

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 Coke

Drinking Beer

25 years old

16 years old

Correct answer: Drinking beer and 16 years old & 7 (P and not-Q). Performance improves in this ‘social contract’ version

P Not-QQNot-P

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

FemaleMale Married Unmarried

Relevant version

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.

FemaleMale Dark hair Fair hair

Irrelevant version

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

9.1% 84.6%

Standard

Version

Social Contract

Version

Relevant

Version

Irrelevant

Version31.9% 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.html 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.