Srinivasan, N. (2008). Interdependence of attention and consciousness. Progress in Brain Research, 168, 65-75.
This article seeks to understand consciousness by exploring the relationship between consciousness and attention. First, an important consideration in following the arguments in the article is the way consciousness is defined - consciousness is taken to mean awareness throughout the article, rather than mere perception. The article presents two conceptualizations of the relationship between attention and consciousness. On the one hand, attention is thought to be necessary for conscious awareness, in that we are not conscious of that which we do not attend to. Evidence supporting this idea is presented, such as studies of inattentional blindness wherein irrelevant stimuli are not reported as being seen when participants were not aware the stimuli would be present (Mack & Rock, 1998), or studies of change blindness wherein subtle changes in objects are not perceived outside of focused attention on the object (Rensink, 2002). On the other hand, consciousness is thought to precede attention, wherein selective attention operates on what is already conscious. From this perspective, perceptual processing leads to conscious perception, and attention acts to focus awareness in order to take appropriate action. While the article cites studies supporting this view (e.g. Lamme, 2003), the studies themselves are not presented, therefore it is hard to draw conclusions about this viewpoint. In essence, the entire argument represents a sort of “chicken-and-egg” dilemma.
It might be useful to return to the definitions presented earlier. Merriam-Webster defines consciousness (n) as: “the quality or state of being aware especially of something within oneself; the state or fact of being conscious of an external object, state, or fact.” Conscious (adj) is defined as: “perceiving, apprehending, or noticing with a degree of controlled thought or observation.” In other words, to be conscious of something we not only are simply perceiving it but also are attending to it to some degree. If this is the case, I would argue that attention is a necessary part of what makes something that is perceived something we are consciously aware of. If this is the case, I would place perception on one end of a continuum, and focused attention on the other, with consciousness operating as degrees along this continuum. Srinivasan presents one interesting theory that, while not exactly the same concept, would support this view: Dehaene et al. (2006) have proposed consciousness and attention may function on a 2x2 matrix in which one factor is stimulus strength (bottom-up), and the other is controlled attention (top-down). This results in four classes of processing: subliminal-unattended, subliminal-attended, preconscious, and conscious (although they don’t really define what is meant by “preconscious”). Again, degrees of consciousness depend on the interaction between perception and attention.
Having degrees of conscious awareness might be important adaptively. At any given moment, there are certain aspects of our internal and external environment that are important to attend to, and others that are not. Without degrees of consciousness operating as a sort of filter, we would be inundated with stimuli, and essentially incapacitated. Procedural memory can be thought of in this way: when we learn to ride a bike, we are initially aware of all the movements of our hands, feet, body, balance, etc. Once we get the hang of it, we no longer think of how our body needs to move in order to ride, and can shift our attention to our surroundings thereby avoiding crashing into walls or being hit by a car. One could only imagine how difficult riding a bike would be if we had to divide our attention between awareness of our bodily movements and information about our surroundings simultaneously. There is some evidence to suggest obsessive compulsive disorder may represent an inability to filter out irrelevant information in conscious awareness, causing an inability to disengage from stimuli. A recent study by Calamari et al. (in press) demonstrated that participants with OCD performed slower on a learning task than healthy controls, yet participants with OCD were able to describe all the elements that went into their selection of specific movements. In other words, they were consciously attending irrelevant information that affected their overall performance, whereas healthy controls were able to learn the task and filter out of awareness all the steps it took to perform the task, thereby allowing them to perform more quickly. It would be interesting to pursue this line of inquiry further to better understand the implications for OCD. Perhaps this could shed further light upon the relationship between attention and consciousness.