The paper suggests that when non-primary visual metaphors are examined with psychological experiments, rather than with corpus approaches, cognitive effects appear only when the metaphor is contextually relevant. The article focuses primarily on the ‘intelligence is brightness’ metaphor, which appears not relevant when the potential source of intelligence is inaccessible. Images of open books with bright backgrounds were rated as more likely to represent works of genius than open books with darker backgrounds. The paper shows that when books are closed, their ‘genius’ is inaccessible and the metaphor ‘intelligence is brightness’ has no effect.