Conformity: Asch's Line Study
Solomon Asch (1951) conducted one of the most famous experiments in social psychology to investigate the extent to which people will conform to a group, even when the group is clearly wrong. His study demonstrated the powerful effect of normative social influence on behaviour.
Asch's Study (1951)
Aim
To investigate whether individuals would conform to a group's incorrect answer on a simple visual judgement task, even when the correct answer was obvious.
Method
- 123 male participants from the USA were tested individually
- Each participant was placed in a group with 6–8 confederates (people secretly working for the researcher who had been told what answers to give)
- The group was shown a series of lines and asked to judge which comparison line (A, B, or C) matched a standard line in length
- The correct answer was always obvious
- On 12 out of 18 trials (the "critical trials"), the confederates were instructed to give the same wrong answer
- The real participant always answered second to last (so they heard the confederates' wrong answers before giving their own)
flowchart TB
S["Standard line<br/>shown to group"] --> G["Group of 7-9 people<br/>1 real participant<br/>6-8 confederates"]
G --> ABC["Three comparison lines<br/>A, B, C<br/>correct answer obvious"]
ABC --> O["Order of answers<br/>real participant<br/>second to last"]
O --> Q{"12 of 18 trials<br/>are CRITICAL:<br/>confederates give<br/>same wrong answer"}
Q -->|Real participant| R{"Conform or<br/>resist?"}
R -->|Conform 37%<br/>NSI 'fit in'| C["Public agreement<br/>with wrong answer"]
R -->|Resist 25% never<br/>conform on any trial| I["Independent answer<br/>says correct line"]
Results
| Finding | Statistic |
|---|
| Participants conformed to the wrong answer on at least one critical trial | 75% |
| Overall conformity rate across all critical trials | 37% (about one-third of answers were conforming) |
| Participants who never conformed | 25% |
When participants were interviewed afterwards:
- Most said they knew the answer was wrong but went along with the group to avoid ridicule or rejection (normative social influence)
- A small number genuinely believed the group was right (informational social influence)
What Asch's Findings Tell Us
1. Normative Social Influence is Powerful
Most participants conformed not because they believed the group was correct, but because they wanted to fit in and avoid being different. This demonstrates the powerful effect of normative social influence, even on a simple, unambiguous task.
2. Individual Differences Exist
25% of participants never conformed — showing that not everyone is equally susceptible to group pressure. Some individuals are more independent and resistant to conformity.
3. Unanimity Matters
In variations of the study, Asch found that conformity dropped significantly when one confederate gave the correct answer. Having even one ally reduced conformity dramatically, because the participant no longer felt alone against the group.
Asch's Variations
Asch conducted several variations to explore factors affecting conformity:
| Variation | Effect on Conformity |
|---|
| Group size | Conformity increased as group size increased up to about 3–4 confederates, then levelled off |
| Unanimity (dissenter) | When one confederate gave a different answer (even a wrong one), conformity dropped to about 5% |
| Task difficulty | When the task was made harder (lines more similar in length), conformity increased |
| Written answers | When participants wrote their answers privately instead of saying them aloud, conformity dropped significantly |
Evaluation of Asch's Study
Strengths
- Well-controlled lab experiment — high internal validity; the only variable that changed was the confederates' answers
- The study clearly demonstrates the effect of normative social influence on behaviour
- The variations provide useful information about factors that increase or decrease conformity
- The findings have been replicated in many studies across different cultures
Weaknesses
- Low ecological validity — judging line lengths in a lab is not representative of real-life conformity situations
- Demand characteristics — participants may have suspected the confederates were working together
- Sample bias — all participants were male American students; findings may not generalise to other groups (though cross-cultural replications have shown similar results)
- Historical and cultural bias — the study was conducted in 1950s America, a time of strong social conformity (McCarthyism); conformity rates may differ in other eras or cultures
- Ethical issues — participants were deceived (they did not know the other "participants" were confederates) and may have experienced stress and discomfort
Cross-Cultural Findings
- Individualist cultures (e.g. USA, UK) tend to show lower conformity than collectivist cultures (e.g. Japan, China), where group harmony is more valued
- Smith and Bond (1993) reviewed replications of Asch's study across cultures and found conformity rates ranged from about 14% (individualist) to 58% (collectivist)
Exam Tip: Remember the key statistics: 75% conformed at least once, 37% average conformity rate, 25% never conformed. When evaluating, always mention the lab setting (low ecological validity) and the historical context (1950s America).
Key Points
- Asch (1951) studied conformity using an unambiguous line-judgement task.
- 75% of participants conformed at least once; average conformity was 37%.
- Most conformity was due to normative social influence (desire to fit in).
- Conformity decreased with a dissenter, private answers, and smaller groups.
- The study is criticised for low ecological validity, male-only sample, and historical context.
Linking Asch to theories of conformity
Asch's findings are usually interpreted through the dual-process account of conformity — the distinction between normative social influence and informational social influence — and Kelman's three types (compliance, identification, internalisation).
- Normative social influence (NSI): most of Asch's participants said they knew the answer was wrong but went along with the group to avoid ridicule. This is a classic demonstration of NSI producing compliance: public behaviour changes but private beliefs do not. When the majority was removed (e.g. private written responses), conformity dropped sharply — exactly what the NSI account predicts, because there is no audience to impress.
- Informational social influence (ISI): when Asch made the task harder (lines more similar in length), conformity increased, suggesting participants used the group as a source of information when uncertain. This shift from NSI to ISI with increasing ambiguity is central to the modern account of conformity.
- Unanimity: a single dissenter cut conformity from 37% to 5.5%, even when the dissenter's answer was itself wrong. This supports the interpretation that Asch's effect is primarily driven by unanimous social pressure rather than by the sheer number of people disagreeing with the participant.
Worked study: Asch (1951) — full write-up