Social Psychology Lecture 11

Group Performance

Jane Clarbour

Room PS/B007 Email jc129@york.ac.uk

Eureka Task (Lorge et al, 1958)

Jealous husbands• 3 married couples have to cross the

river but there is only 1 boat….• Rules of the task:

– Only men can row the boat– Wives can’t cross with another man unless

the husband is present

Lorge et al’s findings…

• Individuals– only 3/21 solved problem

• Groups– 3/5 solved problem

Why????

Overview

• Group processes– Steiner’s typology of task

• Brainstorming• Processes involved in productivity

Additive tasks Disjunctive tasks

Objectives

• Give an account of Steiner’s typology of tasks

• Specify the effects of group size on additive tasks

• Specify the effects of group size on disjunctive tasks

• Review evidence on the effectiveness of ‘brainstorming’ as a technique for maximising group performance.

Theory of group performance Theoretical framework (Steiner, 1972)

• Performance is dependant upon 3 classes of variables:

1. Task demands

2. Resources

3. Process

Task demands

• The procedures necessary to perform a task.– Task demands as ‘building plans’

• house being built• materials needed• tools to use• order of work• Management of total process

Resources

• Relevant possessions of people in group – knowledge– abilities– skills– tools

Group Processes

• What the group does– ‘Process’ refers to the actual steps taken when

confronted with a task– The extent that the total sequence of behaviours

corresponds to the pattern demanded by the task

Formula:-

Actual productivity = potential productivity

(minus losses due to faulty processes)

Faulty Processes

What aspects of group behaviour result in loss of production due to faulty processes?

• Either poor supply of resources? – (low potential productivity)

• Or processes fail to meet demands of task?

• Or both!

Two forms of faulty processes (Steiner, 1972)

Steiner identified 2 forms of faulty process:

1. Coordination loss– Lack of synchronisation

2. Motivation loss– Lack of recognition– Lack of benefit

Performance and group size

• “What is the effect of group size on the task performance?”– Are groups more productive than an individual?– Are individuals more productive than a group?– Are large groups more productive than small

groups?• What are the task demands?• How do the task demands relate to the available

resources?

Effect of group size on performance

• Task demands are initial determinants of both potential and actual production.– Differences in faulty processes may vary:

• Groups may be more productive than individuals, or..

• Individuals may be more productive than a group

– So, necessary to have some kind of typology of task.

Task dimensions

Tasks can be distinguished along 3 main dimensions:

1. Divisible vs. unitary tasks

2. Maximising vs. mimimizing tasks

3. Combinability of the tasks

Divisible vs. unitary tasks

Some tasks are readily divided into sub-tasks – each of which may be performed by a

different individual• Building a house• Playing football• Creating a garden

– Other tasks make no sense if subdivided • Reading a page• Doing a maths sum

Maximising vs. minimizing tasks

• Maximizing/optimizing– Maximizing: (quantity)

• Doing task as much as possible• Doing task as quickly as possible• Generating many ideas• Scoring the most runs

– Optimizing: (quality)• Accuracy of bookkeeping • Weather forecasting• Writing your essays!!!

• Minimising– doing as little as possible

How combinable are the tasks for group members?

• Additive tasks – Group product = sum of the members

• Conjunctive tasks – A task which everyone must perform

• Disjunctive tasks – The group selects from individual member’s judgments, requires a

choice of answer among several possible alternatives

• Discretionary tasks– Conditions sometimes may allow different members to contribute

more or less (varied weightings) by assigning:• Total weight to single member• Equal weight to everybody• Or granting each person a different weight

Individual products of group members

• “What is the effect of group size on task performance?” – Meaningless question without a

satisfactory taxonomy of tasks (Steiner, 1972, 1976).

Additive tasks

Early experimental evidence

RINGLEMANN (1913) A French agricultural engineer who conducted most of his research

in late 1880’s.

1, 2, 3, or 8 people pulling on rope– Device measured the exact mount of forced exerted on the rope

• 63 kilo (1 person)• 118 kilo (2 people)• 160 kilo (3 people)• 248 kilo (8 people)

Group efficiency

• Results showed an INVERSE relationship between the number of people in the group and individual performance– As more people pulled, they used less effort!– Found that a large group needed only half the

effort per person than a small group• Attributed to co-ordination losses (pulling at different times) • Additive tasks – group performance is better than individual’s

performance when on own, although relative efficiency per person may decrease with increasing group size.

Conjunctive Tasks

• A task that every group member must perform– Performance of group dependant upon weakest

group member (i.e relay race, or group accent up the Tor)

– Performance depends on the relative abilities of the individuals concerned

– With increasing group size performance would be expected to decrease due to increased possibility of weak group member.

Disjunctive Task

• A task that requires a choice amongst several possible alternatives – Potential productivity of group is determined by the most

competent member• If one member of the group can perform the task, the group

can, possibly, still perform it• With increasing group size, you expect better performance

Conjunctive Disjunctivemore people = more people =

lower performance better performance

Disjunctive task: early experimental evidence

TAYLOR & FAUST (1952)

Game of ’20 questions’ (disjunctive as have to make a choice between several alternatives)

• Ss divided into categories– Working alone (x 15)– Working in pairs (x 15)– Working in groups of 4 (x 15)

• Ss given 4 problems a day for 4 consecutive days and allowed to ask 30 questions– Experimenter can only reply:

• Yes / No / Partly / Sometimes / Not in the normal sense of the word.

• DVs = no. of questions, failures, & time taken to solve problem

Results TAYLOR & FAUST (1952) • Superiority of groups over individuals in terms of

– Fewer questions asked– Fewer wrong answers given– Less time taken per problem

• Groups superior to pairs:– Fewer wrong answers given

• Individuals superior to groups and pairs:– For ‘man-minutes’ (e.g. time x no of people in group) Individuals

were quicker than pairs, who were quicker than groups (in terms of man-minutes to reach a solution, rather than actual time)

• So, cheaper to pay individuals by the hour than groups by the job

Early conclusions (Taylor & Faust, (1952)

• Disjunctive tasks– superior performance with groups (well

established finding)

• But this effect is inversely proportional to group size

– Individuals are more effective (in terms of man-minutes)

• Steiner suggests that superior performance of groups is due to the greater resources which they possess.

Brainstorming Osborn (1957)

• Special kind of group process– This is creative– Increased numbers of people disproportionately

increase number of ideas generated

• Rules of brainstorming– Free the individual from self-criticism and criticism

of others– The more ideas the better– Can adapt others ideas– Can combine ideas– Should not be critical…

Empirical evidence (MULLEN et al. 1991)

Meta-analysis of 20 studies of brainstorming

• Compared face-to-face groups operating under brainstorming conditions against ‘nominal groups’– Nominal groups were individuals who were

working alone but their ideas were subsequently pooled.

– Productivity was measured in two different ways• Quantity: the number of non-redundant ideas• Quality: involved rating of the ideas

Results (MULLEN et al. 1991)

Meta-analysis of 20 studies of brainstorming– Individuals generated more ideas than face-to-

face groups– Productivity LOSSES increase with the size of the

group– Both individuals and groups work best without an

‘expert’ giving guidance– Most ideas were generated when responses were

written down and not publicly shared

Why production losses in brainstorming occur

• Free-loading (social loafing)

– Motivation loss• Individual members expect that all ideas will be

pooled (group credit)

– Group allocation?

Effects of group allocation(Diehl & Stroebe, 1987)

• Allocation of group affects productivity– Design: 2 x 2

• Results:– Only 8% of variance explained by credit given– Most of the effect explained by group allocation

• Conclusion:– BRAINSTORMING GROUPS LESS PRODUCTIVE

Group type

Credit type Nominal Brainstorming

Group credit

Individual credit

Summary

Task dependent performance (Steiner)

• Additive & disjunctive tasks– Performance increases with increased group size

– But relative efficiency declines

• Conjunctive tasks– Performance decreases with increased groups

size in conjunctive tasks

Mullen et al. 1991– don’t need to invoke any special group

process for brainstorming – Group superiority over individuals can be

explained by interpreting brainstorming as a conjunctive task

But all this depends upon equal status…

Group structure

• Structure of group is independent of the people who occupy the various positions– Each person plays a ROLE within the

group• Roles are determined by social norms, rules of

conduct• Each role is evaluated differently by others• Each role has differing status

– But how does status emerge?

Interaction process analysis (IPA)

• Problem solving groups of unacquainted persons

• Observational analysis of behavioural categories (4 categories)– Interpersonal style of leadership

• Positive socio-emotional behaviour

• Negative socio-emotional behaviour

– Task directed style of leadership• Task behaviours

• Behaviours relating to exchanges of information

Expectation-states theory

• Emergence of group leaders– Higher status roles exert more influence

over production than lower status roles (Torrance, 1954)

• Assertive people are more influential than non-assertive people (Ofshe & Lee, 1981)

• Males are more influential than females, blacks, and younger people (DeGilder & Wilke, 1994)

Matching of leaders with resources

• By matching people with subtasks most qualified to perform.– Some resources give rise to higher

expectations of task completion than others (but not always!)

– Hemphill (1961) suggests need to consider both the nature of the task and the availability of a group member with the required resources:

• Groups must feel that task success is possible• Groups must attach value to task success• The task must require co-ordination and communication

Supplementary reading for group performance

• Wilke & Arjaan Wit (2001) Group Performance (pp. 445 – 478)

In Hewstone, & Stroebe, ‘Introduction to Social Psychology’ (3rd edn). Blackwell Press