The perceived interactions, induction and assimilation between colours presented on a computer screen were investigated for seven participants who gave estimates on the perceived colours. A method based on memory estimation was used. In one experiment, a red – green scale was used, while in a second experiment a white – green scale was used. The distance between objects, shape of objects and colour of objects was varied. A distance effect of colour interaction was found in both experiments, but stronger for the red – green scale. For objects adjacent to each other the interaction effects were statistically significant. For objects not adjacent to each other some smaller effects occurred. No shape effects were found. Assimilation effects were shown for the red – green colour combinations. The participants seemed to use their own internal memory scale for their judgements. A theoretical model for distance effects of colour interaction is also presented.