The effects of reference schemes (reference mode - constant vs. balanced-, number, position, and nature - stronger vs. weaker) on the performance of replicated duo-trio tests were investigated using four versions of duo-trio protocols (DTF, DTM, DTFR, and DTFM), using two different pairs of tomato juices with different sodium content. Examination of proportion of correct answers (Pc) and d' estimates indicated that when the cognitive strategy was fixed to the comparison of distances (COD) strategy, the constant-reference mode showed the superior test performance over the balanced-reference mode, only for DTFM performed using the stronger reference. Among the tests with the balanced-reference mode, for DTF, estimates of d' of the tests using the stronger-reference (W-odd) were significantly higher than tests using the weaker-reference (S-odd), whereas the opposite was true for DTM, revealing the operational influence of the reference position. In general, the DTF or DTFM using the stronger (saltier) product as a constant-reference is recommended as an operationally more powerful protocol to discriminate products having high sodium contents.
Bibliographical noteFunding Information:
The authors thank Dr. Michael J. Hautus and Dr. Rune Haubo Bojesen Christensen for their valuable comments and suggestions that helped improve the focus and readability of the paper. This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science, and Technology (No. 2009-0076537 ).
- Reference scheme
- Sensory difference test
- Sequence effects
- Sodium reduction