Collative motivational preferences for increasing complexity in kindergarten and fourth-grade children were studied by varying the types of elements that constituted complexity gradation conditions along a similarity-distinctiveness continuum. A paired-comparisons procedure was used to assess children's relative preference for one to five levels of complexity within each condition. The highest gradation condition yielded a clear positive function between preference and number of elements, as well as the most reliable performance by children, but the two lower conditions yielded both positive and negative functions when subsamples were analyzed in homogeneous groupings. Obtained negative functions were interpreted as aesthetic or affective dimensions conflicting with the collative exploratory dimension. Differences between gradation conditions were consonant with a proposed arbitrary definition of variety as a distinctive condition of complexity.