Performance of 20 subjects in discriminating between members of a homologous series of aliphatic aldehydes. Each data point represents the percentage (means ± SD) of correct choices from 10 decisions per odor pair and subject. Filled symbols indicate odor pairs that were not discriminated above chance at the group level. The figures above the abscissa indicate the number of subjects that failed to perform above chance in the corresponding task. 1. n-butanal; 2. n-pentanal; 3. n-hexanal; 4. n-heptanal; 5. n-octanal; 6. n-nonanal; 7. n-decanal.