Can biographical information bias decision-making when determining whether two people are siblings?

Abstract

Previous literature has demonstrated that it is a difficult task for individuals to use faces to detect relatedness, regardless of whether it is a sibling or familial relationship. To make this task easier for the decision maker, it makes sense to provide them with some supplementary information. However, past studies also suggest that this additional information can bias the decision outcome. Therefore, the current study aimed to determine the impact of providing limited biographical information (such as name and date of birth) on human decision making. Using a within–subjects repeated measures design, participants (N = 49) were required to complete 144 sibling determination trials, where they had to look at two faces and determine whether they were siblings or not. There were three experimental conditions: (1) no biographical information, (2) correct biographical information, and (3) incorrect biographical information. The data were analysed using ANOVA and t-tests. Overall, sibling determinations were typically slowest, and made with less confidence and accuracy when incorrect biographical information was provided. However, when correct biographical information was provided, performance did not always significantly improve when compared with no biographical information given. Consistent with previous literature, the results also suggest that it is harder to declare that two people are siblings than it is to declare they are not. These findings can benefit a range of government agencies that have to make decisions based on facial imagery. Furthermore, with more diverse and publically available databases that are sibling-specific, future research in this field can be enhanced.