This study explores the reasons why colour words and emotion words are frequently associated in the different languages of the world. One of them is connotative overlap between the colour term and the emotion term. A new experimental methodology, the Implicit Association Test (IAT), is used to investigate the implicit connotative structure of the Peninsular Spanish colour terms rojo (red), azul (blue), verde (green) and amarillo (yellow) in terms of Osgood's universal semantic dimensions: Evaluation (good—bad), Activity (excited—relaxed) and Potency (strong—weak). The results show a connotative profile compatible with the previous literature, except for the valence (good—bad) of some of the colour terms, which is reversed. We suggest reasons for both these similarities and differences with previous studies and propose further research to test these implicit connotations and their effect on the association of colour with emotion words.