Imagine that you are a psychologist who wants to determine the earliest point in human development at which an infant can demonstrate specific skills, such as the ability to judge distances or to differentiate between lines at different angles

Suggest research approaches and techniques that might be helpful in studying these questions. Note the difficulties that
might be expected.

What will be an ideal response

Students may suggest various measures to gauge an infant's physiological
response such as heart rate, sucking response, facial expressions, eye movements,
and eye fixation. The difficulties inherent in any research with infants include: their
short attention span, difficulty in recognizing specific behaviors that can be
objectively measured, and the relatively large variations in developmental
progression at this young age. Since virtually all such research is based on
observation, experimenter bias is always a risk. The student should refer back to the
concepts from Chapter 1, e.g., "Scientists seek to progress from opinion to truth,
from subjective to objective, from wishes to outcomes."