By 1950, the results of attempts to relate brain processes to mental experience appeared rather discouraging. Herring suggested that different modes of sensation, such as pain, taste, and color, might be correlated with the discharge of specific kinds of nervous energy. However, subsequently developed methods of recording and analyzing nerve potentials failed to reveal any such qualitative diversity.

Although qualitative variance among nerve energies was never rigidly disproved, the doctrine was generally abandoned in favor of the opposing view, namely, that nerve impulses are essentially homogeneous in quality and are transmitted as “common currency” throughout the nervous system.

According to this theory, it is not the quality of the sensory nerve impulses that determines the diverse conscious sensations they produce, but rather the different areas of the brain into which they discharge, and there is some evidence for this view.In one experiment, when an electric stimulus was applied to a given sensory field of the cerebral cortex of a conscious human subject, it produced a sensation of the appropriate modality for that particular locus, that is, a visual sensation from the visual cortex, an auditory sensation from the auditory cortex, and so on. However, cortical locus, in itself, turned out to have little explanatory value.

1. The author mentions ―common currency‖ in line 13 primarily in order to emphasize the

(A) lack of differentiation among nerve impulses in human beings
(B) similarity of the sensations that all human beings experience
(C) similarities in the views of scientists who have studied the human nervous system
(D) continuous passage of nerve impulses through the nervous system
(E) recurrent questioning by scientists of an accepted explanation about the nervous system



2. The description of an experiment in which electric stimuli were applied to different sensory fields of the cerebral cortex tends to support the theory that

(A) the simple presence of different cortical areas cannot account for the diversity of mental experience
(B) variation in spatiotemporal patterning of nerve impulses correlates with variation in subjective experience
(C) nerve impulses are essentially homogeneous and are relatively unaffected as they travel through the nervous system
(D) the mental experiences produced by sensory nerve impulses are determined by the cortical area activated
(E) variation in neuron types affects the quality of nerve impulses



3. Which of the following best summarizes the author‘s opinion of the suggestion that different areas of the brain determine perceptions produced by sensory nerve impulses?

(A) It is a plausible explanation, but it has not been completely proved.
(B) It is the best explanation of brain processes currently available.
(C) It is disproved by the fact that the various areas of the brain are physiologically very similar.
(D) There is some evidence to support it, but it fails to explain the diversity of mental experience.
(E) There is experimental evidence that confirms its correctness.