We bring dogs into a lab settinga kennel-like structure where the dogs are in a no-light setting. The bowl of a small amount of food slides through a small slot door into the dog's holding area. Each dog receives two bowls 4 hours apart, one with the greater vegetable content and one with the original content, where the order is randomized. Speed to first bite is measured as well as the time to consume the full food amount. The dogs are removed from the holding area for exercise and play between bowls. The sample contains 12 different breeds and sizes of dogs.

In this dog food experiment, the researcher is concerned that the dog might not be as hungry for the second bowl as for the first and that the time-to-first-bite measurement might be slower as a result. The researcher is concerned about ________.

Multiple Choice

• instrumentation
• maturation
• history
• selection
• testing