One hundred seventy-seven college students completed personality measures including the MMPI-168, and reality-discrimination measures including a timed discrimination task developed by the first author. Previously on such a timed task, normal subjects discriminated percepts more quickly from images of perceptual vividness than from faint images, as if they registered more “central innervation” during more vivid imaging. Presently, on each of the four practice trials and forty-four timed trials in Task 1, subjects fixated on a dot, perceived a stimulus to one side, imaged an identical stimulus on the other side and rated its vividness while continuing to image. Then, either the dot became a P and subjects pressed a button on the side of the percept, as quickly as possible, or the dot became an I and subjects pressed a button on the side of the image. The slope, within subject, of image/percept discrimination times over image-vividness ratings was computed for the 149 subjects who rated some of their forty-four images more vividly than others. It was predicted and found that self-described hallucinators and MMPI-defined paranoids discriminated percepts less quickly from vivid images, as if the greater “central innervation” behind more vivid images is not registered by psychosis-prone subjects.

A contextualizing image (CI) is a powerful central image of a dream which appears to “contextualize” (provide a picture-context for) the dreamer's emotion. For instance, dreamers who have experienced any serious traumatic event sometimes dream, “I was overwhelmed by a tidal wave.” This appears to picture their feeling of terror and/or vulnerability.

Following a review of introspectionist, dualist, and functionalist theories of self-consciousness, a mind-brain monitoring theory is developed. According to monitoring theory, self-consciousness is one's tacit knowledge that one is experiencing sensations: in particular, that one is imaging sensations or that one is perceiving them. Such knowledge is the phenomenal consequence of neurally monitoring whether one's sensations are centrally innervated images or peripherally innervated percepts. As a corollary of the present theory, dream images are interpreted as unmonitored images. Other hallucinations, which also arise in the absence of self-consciousness, are similarly interpreted. As another corollary, “subconscious” percepts are interpreted as unmonitored percepts. Experimental and clinical evidence in support of these and other corollaries is reviewed.

In studying waking images and hypnotic hallucinations, most psychologists have implicitly adopted Hume's sensory continuum theory: that perceived sensations and imaged sensations differ only inasmuch as the latter tend to be less vivid. The current research contrasts sensory continuum theory with an alternative theory: that the central innervation of waking images, especially vivid images, is neurally monitored and tacitly known. To the extent that vivid images demand a greater amount of central innervation, the image-monitoring process should register them more quickly than faint images, even though vivid images are closer to percepts on the sensory continuum. Consistent with image-monitoring theory and contrary to sensory continuum theory, waking subjects discriminated percepts more quickly from vivid images than from faint images. In contrast, deeply hypnotized subjects did not discriminate percepts most quickly from vivid images. The latter result suggests that deep hypnosis attenuates the monitoring process and, thereby, turns “centrally innervated” images into “unmonitored” hallucinations – the most vivid of which tend to be least distinguishable from hypnotic percepts.

This article reviews and summarizes a number of published studies as well as recent unpublished work by the authors on Boundaries (Thin vs. Thick Boundaries) and various aspects of dreaming. Analysis of data by groups as well as by individuals demonstrates a surprisingly high correlation between thinness of boundaries and dream recall frequency. Thin boundaries appears to be the only personality measure clearly related to dream recall frequency. We also demonstrate a relationship between thin boundaries and dream content. Dreams of persons with thin boundaries are rated more dream-like, more emotional, and more bizarre in a number of studies. Thin boundaries are correlated especially with Central Image Intensity—a measure that is elevated in powerful dreams, dreams after traumatic events, and dreams after 9/11/01. These results strengthen our view that the “trait” continuum running from very thick boundaries at one end to very thin boundaries at the other is closely related to the “state” continuum running from focused waking activity at one end, through waking fantasy and daydreaming, to dreaming at the other end.