Attention: The Gateway to Conscious Experience.

Attention: The Gateway to Conscious Experience. A Review of Jesse Prinz’s AIR Theory of Consciousness. 

Abstract: 

In the following paper, I explain and support the view of Jesse Prinz that attention is necessary and sufficient for consciousness. Evidence used to support Prinz’s AIR theory of consciousness is summarized and examined with respect to Unilateral Neglect, Inattentional Blindness, and Attentional Blink, and objections are considered. Where necessary, suggestions are made for potential future research in areas which could help to lend greater support to empirical evidence where needed. 

Introduction: 
While philosophers have sought to explain how physiological processes in the brain give rise to subjective conscious experiences, and psychologists have sought to identify the neural correlates of conscious experience, recent claims of attention being necessary and sufficient for consciousness could imply that studies in attention will better inform our understanding of conscious experience. In the following paper, I will explore the AIR (Attended Intermediate-level Representations) theory as described by Prinz (Prinz, 2012), who holds the belief that attention is both necessary and sufficient for consciousness. Before this, I will provide an overview of the various forms attention and consciousness are said to take, in order to better understand Prinz’s position. Empirical support for AIR theory will be presented and assessed, and I will later describe the common objections and counterexamples to AIR theory. 

According to Jesse Prinz, attention is both necessary and sufficient for consciousness (Prinz, 2012, pp. 89-90). This means that without attention there can be no conscious experience, and wherever we find the mechanisms of attention at work we will also find conscious experience. Unfortunately for anyone first embarking study into the nature of conscious experience, it is quickly discovered that there are many theories which place different emphasis on the properties which are relevant in defining the subject. With many competing theories and terms of attention and consciousness, it is therefore essential that I expound upon all relevant operational terms, which are used by Prinz in his arguments. Before I do, however, I will highlight the various terms, which fall under the umbrellas of attention and consciousness. Doing so will allow for greater distinction of Prinz’s theory upon description. 

Operational Definitions of Attention: 
For attention, we have the two major categories of “Bottom-Up” and “Top-Down” attention (Montemayor et al., 1969). Bottom-up attention relates to processes, which are first instantiated externally from an organism’s environment, and is also called “effortless attention”. In this sort of process, information is received from the environment from an organism’s sensory receptors, transduced into electro-neuro chemical signals, which propagate from the peripheral nervous system to the central nervous system where any relevant properties of the stimulus are perceived and able to be efficiently acted upon if necessary. One of the more relevant terms to this paper which involves bottom-up attention is “visual popout”, which refers to the process of the visual system being attracted by particular salient qualities within the environment, capturing attention over other less salient properties within the environment. 

In contrast to the effortless attentional processes of bottom up attention are the goal driven, effortful attentional processes of top-down attention. Relevant forms of top down attention, which are discussed in this paper would involve such actions searching for, monitoring, and tracking information in a purposeful or intentional manner. For example, being asked to count the number of passes made by players on a basketball team would require attentional processes of tracking and monitoring. In reality, top-down and bottom-up processes interact together in many real life situations. The basketball monitoring task requires bottom-up attentional processes which are sensitive to information about movement, while top-down processes allow us to select relevant information for tracking and executing the intentional component of the task. While the two categories of attention often work together in normal ecological contexts, they have been dissociated as involving different neuronal processes within the brain. Whether or not the dissociation between top-down and bottom-up attentional processes is a critical distinction to be made in determining the necessity and sufficiency of attention for consciousness is an issue which is worth exploring. However, it will not be explored in this paper, for the sake of space. Prinz argues that the common factor in all forms of attention (regardless of neurophysiological differences) is that it allows the contents of experience to be available to working memory (Prinz 2012, pp. 97). For now, it is sufficient to understand that for Prinz, this availability to working memory by attentional processes is sufficient for consciousness. 

Operational Definitions of Consciousness: 
Much like “attention”, “consciousness” is a loaded term, which requires further distinction. Common use of the term “conscious” often simply refers to the process of being in a waking state, being alive, or aware of our surroundings. We can have subjective conscious experience of our environment based on information relayed to us by our senses, called “sensory consciousness”. On the question of the origin of sensory consciousness, it is suggested to be an evolutionary adaptation to compensate for increasingly complex neural hierarchical processing as sensory systems evolved from more simple neural pathways (Fienberg et al., 2016). Subjective sensory consciousness is argued by some to arise after four to five neuronal hierarchical levels are developed, as a means of unifying information processing from various modalities and execute intentional action (Kim, 1992, pp. 121-122). In other words, subjective unified consciousness is nature’s solution for efficient real-time processing of information for complex neural systems (Fienberg et al., 2016). How this subjective, qualitative experience is realized in a physical system is the issue at hand for this paper. Prinz’s answer to this question will soon be considered in detail. 

Criteria for the Ascription of Consciousness: 

Other than strict sensory experience, other abilities are considered critical to the sort of consciousness scientists and philosophers are concerned with when describing the relationship between attention and consciousness. Report-ability, the ability to verbally and explicitly report experiential states is considered very high on the list of criteria for consciousness. Conscious agents are able to learn, being able to respond to situations in their environment in flexible and rational ways (as opposed to lower organisms which are only capable of inflexible and non-cognitive responses). Learning requires us to not only represent and track relevant information within our environment, but to flexibly represent such information in various ways in order to come up with solutions to novel problems. This reasoning allows for another measure of consciousness often discussed in behavioural studies, “intentional action” which literally means action with intent or purpose to attain a goal. “Metacognition” refers to the ability of an agent to represent its own intentional representations, or to think about the contents of their own mental states. For some, metacognition, or meta-awareness, is critical in assessing consciousness, while for others, it is not a relevant property to consider in attributing consciousness. Akin to the use of top-down and bottom-up attention as a division of attentional mechanisms, sensory and metacognitive subjective conscious states have been termed first order and second order conscious states, respectively. A first order representationalist would argue that all that is required for the ascription of consciousness is sensory consciousness, while second order representational theorist would say that metacognition of representational content is necessary for consciousness. 

Assessing the presence and degree of conscious awareness has been argued to require a conception of consciousness to be that of a cluster concept consisting of such relevant properties such as report-ability, learning, intentional action, neurophysiological response to environmental stimuli, etc. (Shea et al., 2010). Consciousness as a cluster concept allows for the conception of consciousness to exist on a continuum rather than a discrete “all or nothing” kind of thing that is had by an agent. The problem is that with such diverse (what I will call) relevant features to the ascription of consciousness, the word consciousness can mean very different things in different contexts. Is this a problem? Since we are asking about the nature of the relationship of consciousness in conjunction to attentional processes, the operational definition of consciousness can be constrained to the sorts of consciousness which occurs in conjunction with or negation from attention. A more formal operational definition of both attention and consciousness will soon be provided in the context of Jesse Prinz’s AIR theory of consciousness. 

Up to this point I have given a broad survey of uses of the terms “attention” and “consciousness”. I have explained that attention can be thought of as an umbrella term for effortful top-down and effortless bottom-up processes, as well as different criteria used for the ascription of consciousness, in terms of first order and second order representational theories of content. We are now in a better position to understand Prinz’s arguments for the necessity and sufficiency of attention for consciousness by narrowing in on his use of terms. I will now describe Prinz’s AIR theory of consciousness and later consider evidence for his claims, as well as assess how he handles objections raised from other researchers who do not agree that attention is necessary and sufficient for consciousness. 

Prinz’s AIR Theory of Consciousness: 

The “AIR” in AIR theory stands for “Attended Intermediate-level Representations”. It is described by Prinz as a two part theory of consciousness, which answers what he describes the “what” and “how” of the attention/consciousness relationship. As stated by Prinz, “Consciousness arises when and only when intermediate-level representations undergo changes that allow them to become available to working memory” (Prinz, 2012, pp 97). In the following paragraphs, I will dissect this statement made by Prinz in order to allow a more complete appreciation of exactly what this statement entails. This will allow us in future sections to more easily differentiate AIR theory from other theories that involve the constructs of perception, attention, representations, and working memory in relation to consciousness. 

Perception: 
I cannot first explain Prinz’s operational definition of consciousness without first outlining what he regards as necessary and sufficient for perception. Prinz distinguishes between conscious and unconscious perception. Perception is described as involving activation of all neuronal hierarchical levels from low, intermediate to high. Discussed often are the cortical levels within the visual cortex, from V1-V7, but the concept of activation of all levels of processing extends to the other modalities as much as vision. Unconscious perception can be measured by implicit measures on task performances such as in priming studies, and performance on procedural learning tests. Unconscious perception includes activation of all levels of processing, including semantic processing regions, which allows for priming effects demonstrated in tests. What distinguishes unconscious perception from conscious perception in assessment is commonly the trait of report-ability. Tests for conscious perception often involve a mix of explicit recollection, recognition and verbal report-ability of the contents of perception. 

Prinz’s Conceptions of Consciousness: 

Before reviewing evidence for Prinz’s claims, it is worth noting in advance that there exist two conceptions of consciousness within his theory, both relying on the presence of attention. For AIR theory, it is possible to have a conscious experience of representational contents without explicit recall of exact details of the object of experience. The second conception of consciousness in AIR theory is the explicit recall and report-ability of the object experienced. What differentiates both cases of consciousness, we will find, is the involvement of working memory. For now it is sufficient that we have established Prinz’s conception of conscious to refer to phenomenal contents, and involving report-ability. Before we discuss working memory, we must return to the unconscious/conscious divide, and what instantiates this dissociation. 

Both unconscious and conscious perceptions involve the activation of all levels of perceptual processing. Unconscious and conscious perception are distinguished by tests utilizing implicit and explicit measures, respectively. Thus far, we have outlined the theoretical criteria of these two forms of perception, and the neural similarities underlying them. Granted that we understand that both forms involve the activation of all levels of neuronal-perceptual processing, what is the material basis for their distinction? As the above quote by Prinz states, consciousness arises when the representational contents of perception are made available to working memory. More specifically, Prinz localizes the representational contents to be at the Intermediate-level of representational processing. More will be said about his support for the localization of the contents of conscious experience after we explore the mechanism by which these contents become available to working memory. This mechanism is, allegedly, attention. Again, for Prinz, the absence of attention will always result in the absence of consciousness. We will now examine three lines of evidence for the necessity of attention, respectively, by cases of unilateral neglect, attentional blink, and inattentional blindness. 

Unilateral Neglect: 

Unilateral neglect is regarded by Prinz as a pathological condition, which provides evidence that conscious perception is not possible in the absence of attentional mechanisms. Damage to the right inferior parietal cortex results in unilateral neglect (Driver & Mattingly, 1988). The term refers to the absence of conscious experience of information in the left visual field. Studies still show the presence of unconscious visual processing (Marshall & Halligan, 1988), and activity of all visual levels on the right side of the brain has been evidenced through neuroimaging (Rees, 2000). 

Evidence of semantic processing comes from implicit test measures in the Marshall and Halligan study mentioned above. The patient was provided with a vertical display of two identical houses, with the exception that the left side of one house depicted flames coming out of the left window. When asked which house they would prefer to live in, they chose the house without flames on 9/11 trials, despite their conscious report that both houses looked exactly the same (not reporting the flames). The Marshall and Halligan study is an ideal example of implicit, unconscious perceptual processing, lacking report-ability of a nevertheless perceived difference, it’s perception being identified by the significance of the statistical probability of selecting the house without flames being above chance. We see evidence of neural activation on all visual levels from both brain damaged and healthy subjects, the critical difference being the damage of the right inferior parietal cortex in brain damaged subjects. Prinz refers to a publication by Husain and Kennard (1996), which argues that the inferior parietal cortex plays a role in the allocation of attention. Neglect is associated with frontal eye field injury, frontal eye fields being frontal cortical structures, which are associated with attentional orienting. 

Thus, Prinz argues that unilateral neglect amounts to a case of unconscious processing due to damage to critical brain regions regarded to be responsible for attentional processing. His argument can be modelled as follows: 

If there is damage to the Right Inferior Parietal Cortex, there is unconscious perception, and all visual levels are active. 
Subjects who do not have damage to these regions have conscious perceptions, and all visual levels are active. 
Full activity of visual levels is not sufficient for conscious perception (follows from 1&2) 
Attentional processes are available if and only if Parietal regions are not damaged. 
Brain damaged subjects do not exhibit conscious perception (reiteration of 1) 
Therefore, attention is the psychological mechanism by which conscious perception is achieved. (Follows from 1, 4). 

Prinz’s argument is valid, and hinges on the soundness of the claim that the right inferior parietal cortex plays said critical role in attentional processes. A critique of this argument would therefore hinge on critical analysis of the Husain and Kennard (1996) study, which will be addressed shortly. Before this takes place, I will summarize two other studies cited by Prinz, this time in subjects without brain damage, which he cites as additional evidence for the necessity of attention for consciousness. These are the phenomena of inattentional blindness, and attentional blink. 

Inattentional Blindness: 
A study which investigates inattentional blindness by Mack and Rock (1998), asked participants to engage with a distractor stimulus which was displayed for 200 msec. The distractor stimulus was a cross, displayed at the fixation of their vision. The 200 msec display time ensured that subjects would view the stimulus at fixation in less time than required for a saccadic eye movement to occur, ensuring they did see the stimulus. A patterned mask was then displayed for 1500 msec to prevent any artifacts of the previous display. Upon the appearance of the mask, participants were asked to report which line of the cross was longer. The critical stimulus (a small square) was introduced after either the third or fourth trial in one of the four quadrants of the cross. The cross was displayed very close to the fixation area which is where the participants were attending to the distractor stimulus. They were later asked if they saw anything other than the cross. Results showed that 75% of subjects failed to report the critical stimulus if it was displayed at the fixation of their vision. The results of this study led the researchers to conclude that when top-down consciousness is fully immersed with a task, there can be no consciousness perception of objects or events which are not relevant to that task, regardless of the spatial location of the unexpected stimulus. There have been objections raised to the design of the study which will later be addressed after describing the phenomenon of attentional blink. 

Attentional Blink: 

Attentional blink is a phenomenon which occurs which bottom up attention is captured by an initially presented stimuli, after which a second stimuli is rapidly presented immediately after at the rate of ten per second. Experimental designs which investigate attentional blink ask the subject to target two presented stimuli which are shown within a sequence of images often being presented at the rate of 10/second. As in top down attention, the failure to detect the second stimulus is due to the fact that attention takes time to activate, and the second stimuli appears too soon (200 – 500 msec) for the attention to the first stimulus to transfer towards the second stimulus. The second stimulus is therefore not consciously experienced by the subject, allegedly due to the limitations of attentional processing. There is evidence, however, of unconscious processing of the second stimulus by EEG (Luck et al., 2000), as Prinz’s account of unconscious perception involving all levels of the visual perceptual hierarchical would predict. The attentional blink phenomenon therefore lends further support to the concept of unconscious/conscious experiences being determined by the modulation of attention. 

Inattentional blindness and attentional blink together appear to strongly suggest the necessity of top down attention and bottom up attention for conscious perception, respectively. Along with unilateral neglect in brain damage patients, it would appear that attention indeed is necessary for consciousness. Phenomena such as visual pop out show that attention is sufficient for conscious experience, as salient objects quickly capture our attention and we are conscious of them effortlessly despite any significance to the object. Thus, we have summarized a foundation of supporting evidence for both the necessity and sufficiency of consciousness. But are there any possible alternative interpretations of the findings of these experiments? I will now further explore any alternative possibilities and interpretations of the data regarding unilateral neglect, inattentional blindness and attentional blink, respectively. 

Upon reviewing the cases of unilateral neglect, the five cases reviewed of brain damage patients have overlapping damage to the right inferior parietal cortex, which is related to frontal cortical structures associated with eye saccades (a form of attentional orienting). Each patient reviewed in the study had delayed saccadic eye movements to .the left (Husain & Kennard, 1996, pp. 653-654). Eye saccades are critical for the visual system to attain a more complete resolution of a scene, akin to a rapid and ongoing scanning of the environment in order to stitch all received details together later in the visual system. The fovea is the region of highest concentration of high resolution photoreceptors on the eye, and saccadic eye movements allow for detailed processing to take place from this region. In looking paradigm studies, subjects are often monitored for eye movements using advanced technology which tracks points of fixation which are significantly governed by saccadic eye movements. It commonly accepted that saccadic eye movements are the beginning of visual fixation, which is ultimately tied to attention. Patients neglect to the left visual field can therefore be reasonably tied to the deficit in efficient left saccadic eye movements, and ultimately attentional processing to anything that would be picked up by the left saccadic eye movements. However, the vertical house experiment described earlier (Marshall & Halligan, 1988) support that there is still unconscious processing in patients with unilateral neglect. Damage to the right inferior parietal cortex leads only to ‘delayed’ left saccadic movements, not to complete cessation of saccadic movements. As attention has already been mentioned as a process of time in the attentional blink studies, it is reasonable to interpret the unconscious perceptions of the burning houses in the Marshall and Halligan study to be the result of what remains of the saccadic movements which allow still for full visual processing of the right visual perceptual regions, yet without sufficient rapidity to fuel bottom up attentional processes which would allow for the patients to form conscious perceptions. Further studies into the relationship of saccadic eye movements and bottom up attention could better inform and lend further support to the connection between right inferior parietal cortex and attentional deficit in unilateral neglect. For now, the phenomenon of unilateral neglect in conjunction with data of other phenomena such as attentional blink (which also involves the time requirements of attentional processing) appears to be enough to accept unilateral neglect as an example of the necessity of attention for consciousness. 

Before I discuss the Mack and Rock study, it is important to note that, of course, there are those who are opposed to the interpretations of such studies that attention is necessary for consciousness. In “Attention and Consciousness”, Christopher Mole argues that the common sense view of attention and consciousness can be maintained (Mole, 2008). Namely, that there can be consciousness without attention, and attention without consciousness. He suggests that there is an element of circularity in the definition of attention used by Mack and Rock as “the process by which a stimulus is brought to consciousness”. In conducting a study which is designed under this preconceived notion of attention to provide evidence of the necessity of attention for consciousness, the conclusion merely ends up supporting their definition. In effect, Mole is charging Mack and Rock with begging the question. 

Of course, any study which is designed to study the effects of “attention”, as defined by Mack and Rock, could possibly bias the results of the design. Mole wishes to argue that subjects still have conscious awareness of the unexpected stimulus, and that the reason for their inability to report the experience is due to the failure of the subjects to have constructed a conscious thought of their experience of the stimulus. Mole cites what he describes as “commonly agreed upon” principles of the “epistemology of perception”, which says that one can only report of construct a response regarding a change (or appearance of an object/event), if they had had the prior conscious construction of the change in a way that would allow them to make the report if probed for it later. In essence, Mole appears to argue for the possibility of consciousness without explicit awareness. 

Prinz would not see a problem with this objection, as his conception of consciousness allows for conscious experience of an event to differ from explicit report-ability on the specifics of that event. In the cases described in the Mack and Rock study where there is no recall of the unexpected stimulus whatsoever, Prinz would argue that this is due to the allocation of top down attention being completely committed to the task, and unlike Mole, would argue that without attentional resources, such conscious experience (despite lack of explicit report-ability of the object of experience), is simply not possible. This is in agreeance with the empirical findings of the Mack and Rock study and extends to similar studies on inattentional blindness which will not be mentioned here. 

It would appear that Moles conception of consciousness is very different than the definition of consciousness which is used by Prinz. As stated at the beginning of this paper, common objections to the necessity of attention for consciousness appear, in one way or another, to involve a failure to agree on what indeed constitutes the necessary conditions to ascribe consciousness. Moles conception of consciousness seems to correspond to Prinz’s conception of conscious awareness without the encoding of the contents of experience by working memory. This is in line with the above cited principle of epistemology of perception which states that unless one can encode a thought of the perception of difference (in change of event or appearance of an object), it is not possible to report. The explicit conscious report-ability is only possible when attention allows the contents of perception to be encoded into working memory in a way which would allow for the report. 

Objections: 
Thus far, I have covered three lines of supporting evidence for the necessity of attention for consciousness in the cases of unilateral neglect, inattentional blindness and attentional blink. I have considered the strength of empirical evidence supporting the claims and objections to the interpretations of these supporting studies. Counter examples have also been raised in objection to the necessity and sufficiency of attention for consciousness. In the case of blindsight, it has been argued that attention can be present without conscious experience, challenging sufficiency. In the case of change blindness, it has been argued that consciousness can be present in the absence of attention, challenging necessity. I will summarize two studies covering blindsight and change blindness, and consider whether any alternative explanations to their results are plausible. 

Blindsight: 
Blindsight is a condition which results from damage to the primary visual cortex which leads to a lack of subjective phenomenal experience, while the ability to localize, and discriminate stimuli represented in their visual field remain intact (Weiskrantz, 1986). A study published in 2004, and titled “Attention may not be sufficient for consciousness”, involved a blindsight patient nicknamed GY (Kentridge, 2004). While fixating on a white spot in the middle of the screen, GY was asked to report the orientation of a line (either vertical or horizontal), within his blind visual field after the presentation of an arrow which cued to one of two spatial locations in said visual field. In some instances, the line was presented in the cued location and in other times it was not. Despite GY reporting no phenomenal conscious experience of the line, his accuracy increased in determining its orientation when the cue stimulus correctly pointed to the lines location. Authors note that despite damage to GY’s primary visual cortex, parietal regions associated with spatial attention and areas designated to spatial representation were not damaged (pp. 834). Given the likely functionality of neural areas devoted to spatial representation and selective attention, and that GY lacks conscious phenomenal experience of the stimulus presented in his blind field, the authors conclude that attention is not sufficient for conscious experience. 

Prinz responds that two physiological processes which occur concurrently with attentional processes (yet are not in themselves attentional processes), can explain the results of the Kentridge study (Prinz, 2012, pp. 113-119). First, despite GY being prevented and monitored for saccadic eye movements by consciously engaging with the white dot in the centre of the display screen, microsaccades can still occur. Microsaccades are miniature versions of voluntary saccadic eye movements, and occur unconsciously without voluntary control. The primary visual cortex does not play a part in microsaccades, and therefore damage to the primary visual cortex does not affect their presence. If GY has unconscious microsaccades in the direction of the spatial cue, it would lead to unconscious spatial processing of that region. Second, eye movements co occur with shrinking of the receptive fields V4 and V5 (Tolias et al., 2001). Prinz argues that the shrinking of receptive fields (caused by the microsaccades) could involve spatial processing which activates preattentive spatial processes. Microsaccades and shrinking of the receptive fields are part of what Prinz calls “orienting” processes are distinct from and more ancient than attentional processes. 

Despite GY’s conscious fixation on the white dot, this unconscious processing could result in high accuracy in identifying the orientation of the line in his blind visual field. Therefore, the success of GY in these studies could possibly be explained by preattentive unconscious processing. It helps to remember, as I have mentioned in previous sections, there is a difference in AIR theory between conscious awareness and conscious reportability, and yet implicit measures of performance (which are arguably what are taking place here) are the result of unconscious perceptions. There is no doubt about the significance of GY’s success on trials, and we cannot deny that there is some sort of mechanism responsible for this. I suggest that further research preattentive processes and unconscious perception would fall in favor of Prinz’s interpretation of the evidence. 

Change Blindness: 
In a study titled “Why visual attention and awareness are different”, Lemme reports a change blindness study, in which he argues challenges the necessity of attention for conscious experience (Lemme, 2003). Change Blindness is a phenomenon that occurs when a subject fails to notice a change which occurs while viewing a scene. The failure to notice this change involves the presentation of a mask which is displayed between 200 and 1500 msec. Changing features of objects within the scene that could fail to be detected are properties such as color, size or orientation. 

In the Lemme study, subjects are presented with an array of eight rectangles, each oriented either vertically or horizontally for 500 msec. After the rectangles are displayed, a mask is presented for 200-1500 msec, and the rectangles reappear with one rectangle having changed orientation. The subject is asked to identify the rectangle which had changed orientation. For each subject, the same rectangle changes orientation. However, each trial is presented under one of three conditions in which a visual cue (a line pointing to the area of importance) is presented either before the presentation of the mask, during the mask, or during the second display of rectangles. In condition A, the line is displayed during the second display of rectangles. Subjects were correct in condition A only 60% of the time. In condition B, the visual cue was presented during the first display of rectangles, allowing subjects to attend to the relevant area in order to report any change. Subjects in condition B were correct 100% of the time. In condition C, the visual cue was displayed during the presentation of the mask (in between the two rectangle displays. Subjects were correct 90% of the time in condition C. Lemme argues that except in the case of condition B, it is unlikely that subjects were attending to the rectangle which changed orientation. Between condition B (100% correct) and condition C (90% correct), there appears to be little difference in the accuracy of identifying the orientation of the rectangle upon second presentation. 

Because there is no cue presented until the presentation of the mask in condition C, Lemme argues that it is unlikely that attention was directed to the changing rectangle (even less likely considering the limited capacity of attention to the eight objects), and that the presentation of the spatial cue during the mask caused subjects to recall the conscious experience of the rectangle in order to compare it to the subsequent stimulus. If this is indeed how subjects come to correctly answer in condition C, it would appear that they are having conscious experiences without attention, and are later able to accurately identify the changing stimulus, and attention plays little role in the reportability of the changing stimulus. If this is the case, it would indicate that attention is not necessary for consciousness. 

Although the cue is presented during the presentation of the mask in condition C, the first display of triangles are displayed for 500 msec, which is long enough time to activate diffuse attentional processes, and also to form an iconic image of the display. Iconic memory is part of sensory memory, similar to a concept of an after image. Although the duration of an iconic image is very short, depending on the intensity of the stimulus, it can remain long enough for attention to engage with it (300-500 msec). Given that the display is presented sufficiently long enough, I would argue that it is likely that iconic imagery is at work in assisting subjects to compare one orientation of the rectangle to the next in condition C. Prinz also mentions the likelihood of iconic memory playing a role in how subjects solve condition C. In addition, he mentions that although given the number of objects in the display exceeds working memory capacity, and that object based attention is not likely to be directed at the changing rectangle, this does not negate the possibility of diffuse attentional processes to be taking place during the display, and therefore would not demonstrate an absence of attention. In light of these considerations, I would conclude that the Lamme study is clearly, at best, questionable account of consciousness in the absence of attention. 

Conclusion: 
AIR theory is supported on empirical grounds in the fields of experimental psychology and neuropsychology. This support is highly integrative and reinforcing. Cases of blindsight are said to demonstrate the presence of attention with the absence of conscious awareness, which calls into question the sufficiency of consciousness. Prinz approaches these kinds of objections by appealing to processes that are associated with attention for alternative explanation (saccadic eye movements and shrinking of receptive fields in the visual cortex), which are not, in themselves, attentional processes. Change blindness studies, which allegedly show conscious awareness in the absence of attention, are also explained by Prinz by similar means, alluding to pre-attentional processes. I have also argued that the presence of iconic memory for a proper duration would allow object based attentional resources to activate upon the cued area during the mask presentation and could also plausibly explain the results. Unilateral neglect, inattentional blindness and attentional blink are all phenomena that demonstrate that in the absence of attention, there can be no conscious experience. I stand in agreeance with Prinz, with respect to what current evidence appears to support. Attention is necessary and sufficient for consciousness. 
References: 

Driver, J., & Mattingly, J.B (1988). Parietal neglect and visual awareness. Nature Neuroscience, 1: 17-22. 
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Tolias, A.S., Moore, T., Smirnakis, S.M., Tehovnik, E.J., Siapas, A.G., & Schiller, P.H. (2001). Eye movements modulate visual receptive fields of V4 neurons. Neuron, 29: 757-767.

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