Dror et al. [11] suggested that as finger marks are more difficult
(bottom-up), the more influence external factors (top-down) have
on the observations. Bottom-up refers to the incoming data, where
as top-down relies on pre-existing knowledge [26]. Top-down has
many forms and manifestations, which include the context in
which the data are presented, past experiences and knowledge,
expectations, and so forth. Expertise is top-down, and as such
experts rely more on top-down information. This allows efficient
and effective processing of the bottom-up data, but also means it
can distort and bias how the data are processed [27]. Variations in
observation among different observers (‘‘inter-observer’’ differences)
and variations in observation for the same observer for the
same task, taken at different times (‘‘intra-observer’’ differences)
are a well-known phenomenon in other fields involving expert
decisions, such as radiologists or other medical technicians [28,29].
In the research reported here we examined three main issues: