Why decision-making can be black and white

Some decision-making can seem “black and white”, but new research shows that the colours can actually affect people’s judgement.

The research, carried out by Dr Theodora Zarkadi of Anglia Ruskin University and Dr Simone Schnall of the University of Cambridge, shows that exposure to these two colours leads people to think in a “black and white” manner and hold more extreme views.

Dr Zarkadi, Lecturer in Psychology at Anglia Ruskin, said: “What our research shows is that colour might literally ‘colour’ moral judgments, by priming a specific mindset.  The contrast of black and white leads to more polarised moral judgments relative to a neutral visual background.”

Dr Zarkadi and Dr Schnall’s work, published in the latest edition of the Journal of Experimental Social Psychology, involved two experiments.  The first saw participants rate a moral dilemma involving a man called Heinz, whose wife is dying of cancer.   Because the pharmacist who sells the life-saving cancer drug charges more than Heinz can afford, the latter decides to steal the drug.

For participants in the experimental condition, the Heinz dilemma was presented on a black and white chequered background, whereas for participants in the control condition it was presented on a uniform grey background.  To control for the potential effects of visual contrast irrespective of moral connotation, a second control group received the dilemma on a blue and yellow chequered background.

To assess judgment polarisation, the authors devised a deviation score from the scale’s midpoint.  The study found that participants in the black and white set gave more extreme judgments that were significantly further from the scale’s midpoint, compared to participants in the grey or the blue and yellow sets.

The second experiment saw participants asked to rate the morality of six social issues (pornography, adultery, using drugs, littering, smoking and use of profane language) on a scale from -5 (= very immoral) to +5 (= very moral).

The social issues were presented one at a time in a random order, with half of the participants viewing them displayed against a black and white chequered background and half against a uniform grey background.  Consistent with the results from the first experiment, the mean deviation of judgments from the scale’s midpoint was greater in the black and white condition.

Dr Zarkadi said: “The two experiments showed that priming participants with a black and white background resulted in them making judgments in a ‘black and white’ and therefore extreme manner, by giving responses closer to the scale’s end points.

“The results indicate that the black and white metaphor was not driven solely by contrast because there was no comparable effect for the blue and yellow pattern in the first experiment.  Instead, there appears to be a specific connotation of black and white that relates to judgment extremity.

“The fact that colour can affect people’s perceptions of right or wrong could have important practical implications, for example in contexts that involve judgments of others’ guilt or innocence.

“Subtle perceptual stimuli in a courtroom, even in fairly innocuous objects such as the colour of floor tiles, might subconsciously influence people involved in legal proceedings leading to biased judgments and decisions when objectivity is of utmost importance.  Discovering the existence of such factors might be the first step toward guarding against their potential influence.”