Until the middle of the twentieth century, most researchers believed that infants possess only the most rudimentary ways of perceiving the world.  Then, in the 1950s, innovative investigative strategies allowed researchers to better assess the complexity of infants' perceptual abilities.Studies on the visual perception of infants used gaze time as an indicator of interest or preference.  In Study 1, 36 babies age 2 weeks to 4 months were shown 6 pictures of identical size simultaneously, such as pictures of a bull's-eye, a bird, three squares of different colors, and a human face.  Researchers recorded the time the infants spent looking at each picture and calculated the mean gaze time for each picture.  It was found that the babies gazed far longer at the human face than at any other picture.Studies on the auditory perception of infants also employed gaze time as an indicator of preference.  In Study 2, researchers exposed infants age 1-4 months to four types of auditory stimuli.  The first type was human speech consisting of a series of randomly selected short words, each stated in a neutral tone, followed by a second of silence.  The other stimuli included environmental sounds (eg, forest noises); neutral, human, noncommunicative sounds (eg, sneezing, coughing, throat clearing); and monkey vocalizations.  A red light was shown on a computer monitor to attract the babies' attention.  Once their gaze was fixed on the monitor, they were shown a picture of a checkerboard along with the auditory stimulus for up to 40 seconds.  The time the infants gazed at the monitor was recorded.  Results indicated that babies preferred human speech to any other sound.Adapted from S. Shultz and A. Vouloumanos ©2010 Taylor & Francis Group, and R. L. Fantz ©1961 Scientific American. Question 31Based on Study 1, which of the following best explains how babies are able to perceive both the form and location of the pictures simultaneously?A.Parallel processingB.Sensory adaptationC.Weber lawD.Signal detection theory