Fig. 1 | Scientific Reports

Fig. 1

From: Evolution of indirect reciprocity under emotion expression

Fig. 1

Average cooperation ratio (\(\eta\)) (and respective standard deviation) promoted by the emotion-based image scoring norm (blue circles) and the baseline image scoring (orange squares), for the different probabilities of accounting for emotion (\(\gamma\)), when all errors—execution, assessment and assignment—are present (\(\alpha =\chi =\varepsilon =0.002\)). While the (low) performance of Image Scoring remains consistent with the literature, by looking at the performance of emotion-based image scoring we obtain clear benefits by using emotional expressions as part of the moral evaluation process—higher \(\gamma\) values lead to higher cooperation levels under the emotion-based norm, while having no impact on the baseline norm. Despite this, such behaviour is non-monotonous: when \(\gamma =1\), cooperation levels under the emotion-based norm plummet. Each data point averages the results of 300 runs with the same parameter configuration. Other parameters: \(b=5, c=1, z=50, \mu =1/z, \beta =1\).

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