Figure 3. Relationships between odours used in set 1 (left panel) and set 2 (right panel).

A solid arrow indicates the occurrence of overshadowing between the components of the mixture. A dotted line indicates the absence of overshadowing. “?” indicates the difficulty in determining the occurrence of overshadowing in this combination of odours due to high levels of generalization from the longer to the shorter aldehyde; the presence of solid arrows linking these odours is suggested by experiment 2. Similar patterns were found between the two sets of odours varying in carbon-chain length, thus indicating that common rules based both on functional group and carbon-chain length determine the occurrence of olfactory overshadowing in ants.