Fig. 1

C. elegans display rational decisions. a A scheme for the Independence of irrelevant alternatives chemotaxis assays. A chemotaxis index (C.I.) (number of worms in A, divided by the number of worms in A and B together) was calculated. Each plate contained ~200–400 worms. b The relative preference for 2-butanone over 2,3-pentanedione is unaffected by increasing concentration of benzaldehyde as a third attractant (two-tailed Wilcoxon signed-ranks test; n = 6). c The relative preference for 2,3-pentanedione over 2-butanone is unaffected by increasing concentration of benzaldehyde as a third attractant (two-tailed Wilcoxon signed-ranks test; n = 6). d, e Introducing AWA- sensed odorants as a third attractant, does not influence the relative preference between 2-butanone and 2,3-pentanedione (two-tailed Wilcoxon signed-ranks test; d n = 8, e n = 6). f Benzaldehyde as a third attractant, does not affect the relative preference between the two AWA- sensed odorants pyrazine and diacetyl (two-tailed Wilcoxon signed-ranks test; n = 6). Two-tailed Wilcoxon signed-ranks test. Bars represent the C.I. of odor A. Error bars represent the standard error of the mean C.I.