RESOURCE THEORY VS. MINDLESS THEORY

Resource Theory and Mindless Theory represent two of the most prominent theories in the study of vigilance. A relatively more recent theory, namely Goal Habituation theory, has also attracted much attention in this field. This week’s post will examine these theories theories in detail, beginning with a summary of the main points of each theory and a comparative analysis of the key similarities and distinctions. As a departure from previous posts, this week’s post will not feature any in-depth summaries of the papers, but will instead reference them throughout this post for evidence and discussion. In the questions and comments section, we will then integrate this week’s readings with those of previous weeks by comparing the debates between mindless and resource theory with those discussed in previous weeks, specifically those concerning the key contributors to the vigilance decrement. After an examination of the competing theories, we will select the most compelling theory by referencing evidence from this week’s readings. Lastly, we will conclude with comments on links to neuroscience and possible future directions.

COMPETING THEORIES AND COMPARATIVE ANALYSIS

Resource Theory

The central tenet of resource theory is the contention that vigilance requires limited processing resources. As Helton and Russell (2011) and Ariga et. al.  (2011) elaborated in their papers, resource theory maintains that vigilance tasks require subjects to make continuous discriminations and thus deplete their mental and cognitive resources, resulting in a decline in their performance efficiency.  Notable supporters of resource theory include Parasurman and Warm, whose vigilance taxonomy and review of advances in vigilance research we discussed last week. Thus, advocates of resource theory espouse the view that the vigilance decrement is due to the decline in “available attention resources” and “cognitive resources available for information-processing” (Helton and Russell, 2011). The robustness of resource theory lies primarily in the abundance of supportive evidence coming from a variety of different experiments, from behavioral, to brain imaging, to mental workload studies, as Helton and Russell (2012) details in their paper. For instance, See et. al. showed objective increases in task difficulty was directly linked to greater lapses of sustained attention. Furthermore, declines in cerebral blood flow in areas of the brain associated with vigilance have also been shown to correspond with the vigilance decrement.  Ultimately, the resource theory posits that the vigilance decrement is a manifestation of the depletion of mental and cognitive resources throughout the course of a vigil.

Mindless Theory

In contrast to resource theory, mindless theory holds that the vigilance decrement arises from the subjects’ inattention or mindless. In short, the subjects demonstrate decreased attention to the vigilance task out of boredom. First described by Robertson and colleagues, the mindless theory states that subjects’ “supervisory attentional system loses effectiveness and ceases to focus awareness on the vigilance task” after a certain time of performing the same, repetitive task. As a result, subjects begin to respond to the task in a “thoughtless manner,” and acts out of routinization rather than attention (Ariga and Lleras, 2011). Since the Mindless Theory is relatively younger than Resource Theory, supportive evidence is slightly more limited. Much of the evidence for mindless theory comes from results of sustained attention to response task (SART) studies. Robertson et. al. (1996) describes this approach as well as its advantages over the conventional perceptual detection-based tests such as the Triplets test. Specifically, SART involves withholding of key presses in response to signals. The rationale behind this paradigm was the view that SART tasks require a “high level of continuous attention” and thus would test uniquely for sustained attention. Results confirmed this hypothesis and indicated that SART was sensitive to vigilance deficits and “predicts reported attentional failures in subjects.” Analysis of SART indices of attentional disengagement (measured through three variables, namely response time speed, anticipations, and omissions of signal responses) have shown a correlation between the vigilance decrement and the subject’s attentional disengagement, thus providing evidence for the mindless theory.

Goal Habituation Theory

The goal habituation theory, though similar to the Mindless Theory, has several important differences with the latter. Proposed by Ariga and Lleras (2011), this new theory attributes the vigilance decrement to the difficulty in maintaining an active goal for a “prolonged period of time.” Specifically, they argue that cognitive goals, such as maintaining attention through a vigilance task, also show habituation effects (described as the “eventual absence of representation of sustained stimulation”), and that it is this “goal habituation” that accounts for the decrement in vigilance tasks. In accordance with this theory, Ariga and Lleras argued “deactivating the vigilance goal would preempt full goal habituation by re-strengthening the goal’s activation,” and thus manifest in an enhancement in vigilance. Results indicated that the “mere prompt” of activating a different goal was sufficient to enhance vigilance, a finding that clearly supports the habituation hypothesis.

QUESTIONS AND COMMENTS

Blast From the Past: Parallels and Distinctions Between Current and Previous Debates

Examination of these competing theories brings to mind clear parallels of the debates we discussed in previous weeks on the key cause of the vigilance decrement. For instance, while signal detection theory held the background event rate responsible, Broadbent and Gregory attributed it to the decline in subject confidence. Upon a closer look, we find that the debate between resource, mindless, and goal habituation theories has clear echoes of the past debates. For instance, resource theory maintains the vigilance decrement is due to a depletion of mental resources, which is rather in line with Parasurman’s argument that memory load contributes to sensitivity decrements. To take this one step further, resource theory’s claim that cognitive and mental resources are depleted also echo See et. al.’s study on the necessity to examine the vigilance decrement in the context of the total task demands, in addition to memory load. Furthermore, the cognitive component addressed by resource theory is also in line with See et. al. and other researchers’ view that vigilance tasks require cognitive resources and that cognitive-based tasks may be different from perceptual-based tasks. Interestingly, however, while See et. al. saw a stabilization of performance and in some cases, a rise in performance, during cognitive tasks, resource theory does not take such observations into consideration. On another note, the Mindless Theory also falls in line with several of Scerbo (1998)’s findings. Specifically, the latter posited that boredom could have an effect in the vigilance decrement, which is clearly echoed in the Mindless Theory’s claims that the vigilance decrement arises out of inattention to the vigilance task. On a more “meta” level, I find the current debates and those that we discussed last week all share one similarity that may explain the existence of the debates: they all hypothesize that one factor or process is the key contributor to the vigilance decrement. However, as will be discussed in the section immediately following this one, the ideal theory should incorporate components of all the candidate theories.

Moment of Truth: Which Theory is Most Compelling (and Why)?

Okay, so here, I’m going to err…cheat a bit. I know we’re technically suppose to select one theory, but I don’t think there’s one theory that is clearly the winner. Moreover, I feel that quite possibly, the “correct theory,” is a mixture of all three theories. I believe the most compelling theory should have the evidence (and claims) of resource theory but also take into consideration the possibilities suggested by mindless and goal habituation theory. For something as complex as vigilance, I don’t think that any one variable or explanation could be the only correct explanation. To do so would be to neglect the complexity of the problem as well as that of the evidence. The key, at least in my opinion, is to recognize that the theories presented are not mutually exclusive. For me, the most compelling theory might look something like this: the depletion of mental and cognitive resources (which is proposed by resource theory) can be due to both mental fatigue and boredom, which may stem from goal habituation. While this is rudimentary, it takes into account many variables such as resource depletion and mental fatigue but also links together possible explanations into one compelling argument. Oh, and disclaimer: I’m not self-complimenting, really. Well, maybe just a tiny bit.

General Questions and Comments

            In this section, I would like to raise a general question that I have wondered about for a long time. It does not address this week’s papers specifically, per se, but this week’s assignment rekindled this question. I know the scientific method is the bible of science, and that everything begins with observation and a hypothesis. However, I feel that once we believe that something is true/i.e. have a hypothesis, we are almost certain to find evidence to support it. In short, it is possible to basically prove anything as long as we look for evidence in favor of our “hypothesis.” Yet, doesn’t this contribute to biased data and results? Aside from undermining the rigorous nature of science research, if this approach indeed biases our findings (and by virtue of being human, we all have preferences, etc.), and if that research is then used to produce clinically relevant products, isn’t this a significant problem? Clearly, I think the scientific method has significant merits. I’m just wondering about a possible flaw. I agree that most of this can be controlled by discipline, but sometimes, I feel that maybe starting out with no hypothesis but rather with the intention of studying something, may be more compelling. Just a thought though.

LINKS TO NEUROSCIENCE

I think it would be extremely interesting to examine the competing theories through the lens of neuroscience experiments. For resource theory, we would need to first define what constitutes “mental and cognitive resources.” We could begin by testing just a few variables such as memory and attention. We can then construct mouse models in which the mutant mice have impaired ability to process information or tire more quickly. If the resource theory is correct, then one would expect the mutant mice to demonstrate a quicker and more pronounced vigilance decrement than the wild type mice. A difficulty that has to be overcome is pinpoint the exact manipulation that would result in impaired information processing. One approach is legion of the hippocampus or frontal cortex. One could also use RNAi to silence genes that are known to be important in attention and information processing. For the mindless model, we can use human subjects. Specifically, we can use fMRI and transcranial brain imaging to see which areas of the brain are activated during repetitive and “boring” tasks, and most importantly, monitor the decline in activation intensity over the course of the vigil. To incorporate goal habituation theory, we can perform a similar procedure, but insert goal-changes sporadically. If the theory is correct, then one would expect to see in increase in activation of vigilance-related brain areas (every time a goal change is promoted) following a decline in those areas after a prolonged time.

REFERENCES

Robertson, I. H., T. Manly, et al. (1997). 'Oops!': performance correlates of everyday

attentional failures in traumatic brain injured and normal subjects. Neuropsychologia

35(6): 747-758.

Allan Cheyne, J., G. J. Solman, et al. (2009). Anatomy of an error: a bidirectional state

model of task engagement/disengagement and attention-related errors. Cognition

111(1): 98-113.

Helton, W. S. and P. N. Russell (2011). Feature absence-presence and two theories of

lapses of sustained attention. Psychol Res 75(5): 384-392.

Ariga, A. and Lleras, A. (2011). Brief and rare mental ‘‘breaks’’ keep you focused:

deactivation and reactivation of task goals preempt vigilance decrements. Cognition

118:439–443.

Helton, W. S., & Russell, P. N. (2012). Brief mental breaks and content-free cues may not

keep you focused. Experimental Brain Research, 219, 34–46.

Image References:

Graduate Studies in Neuroscience (Msc/PhD) http://www.uleth.ca/artsci/neuroscience/graduate-studies-neuroscience-mscphd. (Accessed 13/02/2013).

Eco-Cinema and Film Genre. The Land Before Time and Evolutionary Narratives. http://ecocinema.blogspot.com/2012/06/land-before-time-and-evolutionary.html. Accessed 13/02/2013)