The Physical Dimensions of Consciousness

Boring argues that consciousness is a real entity, as real as the constructs of physical science, and therefore capable of scientific treatment. The book rejects the appeal to immediate sensory 'givens'—the foundation of introspective psychology—by arguing that sensations are themselves constructed from attributes, and that attributes should be reconceived as dimensions: quality, intensity, extensity, and protensity . The central doctrine develops from the premise that scientific reality is always inferential, whether in physics or psychology. Boring contends that consciousness is essentially sensory, and that psychology's task is the complete description of these dimensions, with introspection reconceived as a discriminative response to neural events rather than direct access to mental contents.

A review in Psychological Bulletin called it 'one of the most significant and challenging contributions to theoretical psychology in recent years,' praising the brilliance of its argument . A review in a clinical psychology journal was more critical: while acknowledging that the psychophysiological middle chapters could stand alone as a useful handbook, it faulted Boring's philosophical sections for betraying 'a limited acquaintance with the writings of philosophers,' noting that the mind-body problem had been so thoroughly discussed by philosophy that a new treatment should situate itself within that tradition . The reviewer's main dissatisfaction was with the doctrine of correlation, suggesting the book's psychophysiological core was stronger than its epistemological framing.

The book is a foundational text for the identity theory of mind, the doctrine that conscious experience just is brain activity, described in two different vocabularies. A historical analysis of Boring's influence notes that he was 'undoubtedly the first to formulate this position in terms of the relation of identity,' and that Herbert Feigl, a member of the Vienna Circle, later cited Boring as the originator of the identity theory . Boring's formulation was not a philosophical treatise but a psychologist's attempt to resolve the mind-body problem operationally: if consciousness is a physiological event, then introspective reports are discriminative responses to neural states. This move influenced later identity theorists including Feigl and J. J. C. Smart, though Smart credited U. T. Place rather than Boring.

Boring identifies four dimensions: quality, intensity, extensity, and protensity (temporal duration), with a possible fifth, Titchener's 'attensity' or attention . Each receives a chapter correlating it with neural processes. Intensity is explained through the volley theory of Wever and Bray, reconciling the multiple-fiber theory (supported by irradiation and summation) with the frequency theory (supported by single-fiber recordings) . Extensity is grounded in a 'modified projection theory' of cerebral tridimensionality. Quality maps onto locally distinct receptor and brain action, a kind of 'place' theory. Protensity involves temporal integration in the nervous system rather than mere lapse of time. The correlations are speculative, as Boring acknowledged, but they constitute the book's scientific core.

Reviewers distinguished sharply between the book's psychophysiological content and its philosophical pretensions. The clinical psychology review praised the middle chapters as a 'useful handbook' of theories of intensity, quality, and extensity that could stand alone, but found the philosophical chapters marked by the 'familiar flavor of philosophy as written by the psychologist'—sophisticated by psychological standards but 'almost naive to the professional philosopher' . The reviewer also noted that Boring himself admitted only 'a limited acquaintance with the writings of philosophers.' This reception is characteristic of Boring's career: he was a psychologist writing about philosophical problems for psychologists, not a philosopher engaging the technical literature, and reviewers judged the book accordingly.

The original edition was published by The Century Co. in New York in 1933 (xii + 251 pages) . A Dover Publications reissue appeared in 1963 . The edition matters primarily for availability and pagination: the 1933 Century edition is the source for standard page references, while the 1963 Dover edition is the more accessible reprint. Scholars should specify which edition they cite, as the Dover reissue may have different front matter or pagination. The book has not been widely retranslated; it was written in English and remains an English-language text. No significant editorial controversies surround its publication history.

The two books represent complementary sides of Boring's project. A History of Experimental Psychology (1929) was a historical narrative of the discipline, written from a presentist perspective that shaped psychology's self-understanding for generations. The Physical Dimensions of Consciousness (1933) is a systematic, speculative monograph in which Boring develops his own theoretical position on the mind-body problem. The relationship is one of historicization: the history book explains how experimental psychology arrived at its current problems, while the 1933 book attempts to solve one of those problems—the place of consciousness in a scientific psychology. Together they show Boring as both the discipline's premier historian and a participant in its theoretical debates.