Aresearcher becomes aware that the judges he is using to make observations are becoming more proficient at their task. this improvement among the judges might suggest a potential threat to the internal validity of the study. what is the source of this threat?

Answer:

Instrumentation

Explanation:

Instrumentation internal validity threat:

There are seven instruments internal threat are as follows:

Instrumentation: It is very important for research that the instrument used for the research should be accurate in their measurement because its accuracy will be responsible for the outcomes of the study.  

answer; they both highlight the power of the situation in determining behavior;