What kind of code is most neutral for serving samples in a sensory test?

The choice of using a three-digit number is most neutral for serving samples in a sensory test due to its ability to obscure any potential biases associated with the samples. Three-digit numbers provide enough variability and randomness to make each sample look distinct without lending any direct connotation or meaning to the participants. This helps ensure that sensory evaluations are based purely on sample characteristics rather than any inherent associations participants may form with other systems, such as letters or shapes.

In contrast, single letters can sometimes suggest a categorization that participants might subconsciously associate with traits of the samples. Geometric shapes might also engender unintentional biases based on their familiarity or aesthetic preferences. One-digit numbers, while providing some level of anonymity, lack the complexity and range offered by three-digit numbers, which can lead to participants inadvertently guessing or associating samples based on the limited options.

Using a three-digit numbering system balances the need for uniqueness with the psychological neutrality necessary for effective sensory testing, fostering more objective responses from the participants.