However, in the case of the participants with synaesthesia we expected a full endogenous reconfiguration (a non-significant residual cost in long RSI) due to a reduced or null effect of the exogenous factors, considering that an externally presented inducing stimulus is not necessary to trigger a photism (Dixon et al., 2000).
For synaesthete C, the color task was to indicate whether the color was yellow or not yellow and for participant D, the color task was to indicate whether the photism was red or not red.
The mental set reconfiguration between numbers and photisms in synaesthesia was similar to the real mental set reconfiguration in control group 2 in several factors, such as general mean RT, cost magnitude and cost reduction with RSI.
As we have already pointed out, perhaps the only difference is the cognitive limitation discussed in the context of the relationship between synaesthesia and cognitive flexibility: It is easier for a synaesthete to shift his/her mental set, at least between numbers and photisms. The color task was easier than the number task for Groups 1 (synaesthetes) and 2 (naive control), but the cost asymmetry only occurred with synaesthetes (G1), it being more difficult for them to shift from photisms to numbers than from numbers to photisms.
What it is clear is that photisms produced proactive interference, a real impact in information processing.