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Chapter Summary
This chapter examines the study of consciousness, which has been of interest to philosophers and psychologists for many years. Defining consciousness has been a difficult task, as is exemplified in cases of blindsight, in which one can arguably perceive an object despite not being aware of it. A number of different approaches to studying consciousness have been developed. Some have approached consciousness in terms of having different levels. One such approach was proposed by Tulving. Tulving’s approach is tied to the three memory systems, and each memory system is associated with a different form of consciousness. Procedural memory, for instance, is associated with anoetic consciousness (“non-knowing”), semantic memory with noetic consciousness (“knowing”), and episodic memory with autonoetic consciousness (“self-knowing”). Schooler also pro-posed a three-level framework of consciousness, in which he distinguished non-conscious (unexperienced), conscious (experienced) and meta-conscious (re-represented).
Unconscious or subliminal perception occurs when someone is unaware of a stimulus, but that stimulus has an effect on his or her behaviour. This phenomenon suggests that information that is presented below a limen (threshold of awareness) can still modulate behaviour. Subliminal perception studies have been criticized on the grounds that we cannot be sure that a stimulus was actually presented below the threshold of awareness—it could be the case that the stimulus was consciously perceived and influenced behaviour as a result. Seminal work using backward masking and priming have demonstrated that subthreshold information can be processed without conscious awareness and have later effects on behaviour. Backward masking experiments are examples of the dissociation paradigm and are used to demonstrate that conscious awareness is not necessary in order to perceive a stimulus. It has also been pointed out that it is important to distinguish between objective and subjective thresholds, and this can be difficult to do. To get around this issue, Debner and Jacoby employed a process dissociation procedure which separates conscious and unconscious processes. This procedure requires participants to exclude as a response any item that was consciously perceived. Thus, if an item is included as a response then it was likely perceived at an unconscious level.
The grand illusion of conscious perception refers to the idea that what we see in our visual world is a complete and detailed representation of our world, when in fact it is not. Change blind ness demonstrates that we often fail to notice a change in two seemingly identical images. Our experience of the visual world is often interrupted by saccadic suppression and blink suppression, and in these instances visual processing does not occur, but our brain compensates for these “blind” moments to provide us with a continuous visual experience.
Mind-wandering (or “zoning out”) has been used by Schooler to differentiate between consciousness and meta-consciousness. Meta-consciousness is the moment when you realize that you have zoned out. Episodes of mind-wandering can be assessed by the self-caught method, in which the participant reports when they notice their mind wandering, or through the probe-caught method, in which the researcher presents a probe and asks the participant if they were mind-wandering at the time of probe presentation. Lucid dreaming has also been of interest to researchers studying consciousness. It reflects meta-consciousness because we are aware that we are experiencing a dream. Dreams occur during the sleep stage known as rapid eye movement (REM) sleep. Researchers use an electrooculogram (EOG) to measure eye movements during dreaming as well as an electromyogram (EMG) to measure muscle activity.
Chalmers distinguishes between easy and hard problems of consciousness when trying to understand the relationship between consciousness and the brain. Easy problems can be addressed through cognitive neuroscience methods whereas hard problems require an understanding of the subjective qualities of an individual’s consciousness. Along with blindsight patients, other patients with brain injuries can also aid in our understanding of consciousness. Patients with visual hemispatial neglect have no conscious awareness of half of their entire visual field. Split-brain patients demonstrate that neither hemisphere is conscious of the meaning of a word presented to the opposite hemisphere. Patients with a phantom limb can also inform us about consciousness because, although these patients have lost a limb, they nonetheless still feel that body part as being present, which is suggested to be a consequence of our body schema.
Chapter Objectives
- To understand and be able to distinguish different levels of consciousness.
- To look at unconscious perception.
- To explore meta-consciousness, as illustrated by mind-wandering and lucid dreaming, and how it relates to consciousness.
- To discuss the relationship between consciousness and the brain.
- To explain various deficits of consciousness.