Sunday, November 23, 2008

Week 8& 9: Reasoning and Problem Solving

Litt, A., Eliasmith, C., & Thagard, P. (forthcoming). Neural affective decision theory: Choices, brains, and emotions. Cognitive Systems Research.

Evans, J.S.T.B. (2003). In two minds: Dual process accounts of reasoning. Trends in Cognitive Science, 7, 454-459.

Thagard, P. (2007). Abductive inference: From philosophical analysis to neural mechanisms. In A. Feeney & E. Heit (Eds.), Inductive reasoning: Experimental, developmental, and computational approaches (pp. 226-247). Cambridge: Cambridge University Press.

This week’s readings focus on the process of reasoning and decision making. Throughout each article and chapter, a common theme is reported: both reasoning and decision making appear to be the result of a final solution reached through the interaction of dual processing streams, one involving emotional processing and the other involving more cognitive processing. Evans (2003) presents a dual processing theory of reasoning, whereby two systems essentially “compete” for the final solution. “System 1” processing represents rapid, automatic processing, representing concepts and beliefs that are formed through associative learning. It is through this system that innate and instinctual behaviors are accessed. Evans proposes the end result of the rapid and automatic processing by this system is what becomes available to consciousness. System 2, by contrast, represents much slower, methodical processing, making use of working memory systems to elaborate upon information from System 1, engaging in more sophisticated hypothetical thinking and forecasting, constructing mental models and analyzing possible outcomes. Through this process, System 2 essentially has the capacity to override System 1. Evans presents examples from studies in which syllogisms are used to evaluate the relationship between beliefs and analytical deductive reasoning. In one type of study, participants are asked to endorse only those conclusions that logically follow a preceding premise regardless of their beliefs. Results show participants have a very difficult time overriding prior beliefs, and show belief bias in their endorsement of conclusions, rejecting otherwise logically deduced solutions. For example, in the syllogism “No nutritional things are inexpensive; Some vitamin tablets are inexpensive; Therefore, some vitamin tablets are not nutritional,” participants demonstrated difficulty endorsing this conclusion regardless of the fact it rationally follows the previous premises, having a difficult time “buying” that we can conclude some vitamins are not nutritional based on the fact they are inexpensive. If instructions to participants emphasize the importance of endorsing conclusions only on the basis of their logical merit, participants are able to do it, but only with effort. Evans proposes these studies are representing the process of System 2 inhibition and override of System 1. If System 2 requires working memory and other higher cognitive processes in order to override System 1, then measures of intelligence ought to correlate with ability to inhibit System 1 by System 2. This has indeed been demonstrated, with higher IQ scores correlating with greater ability to find correct solutions in reasoning tasks. In short, the greater cognitive capacity an individual has, the better able they are to go beyond “gut reactions” to problems and find other possible solutions. This is analogous to the stereotype of the reckless, emotional decision-maker versus the cool, calm, collected and calculated one – Inspector Clouseau versus James Bond if you will.

In Thagard’s article, he provides arguments for a neural account of abductive reasoning. Abductive reasoning refers to inference involving the generation and evaluation of explanatory hypotheses. Thagard argues that the process of abductive reasoning is inherently emotional, based on the fact that reasoning occurs first when something is puzzling, which is resolved when a target explanatory solution is arrived at. Both the puzzling nature and the satisfaction with the explanatory solution are in essence emotional events. He suggests that the ability to find causal relations begins with very early perceptual processing, as demonstrated by studies showing infants as young as 2.5 months expect that a stationary object will be displaced when hit by a moving object. Thagard proposes there is a neurally-encoded image schema that establishes the causal relationship tying the neural structure representing hypothesis with the neural structure representing the target explanation. Abductive inference is the “transformation of representational neural structures that produces neural structures that provide causal explanations.” Abductive inference does not only include verbal-linguistic processing but also inference from multiple perceptual modalities (such as deducing from seeing a scratch on your car in a supermarket parking lot and a shopping cart nearby that the shopping cart caused the scratch). All types of inference are inherently emotional in that what motivates one to find a causal explanation is the emotional thrust of puzzlement, and what represents a solution is the satisfaction that solution elicits. Here again, we see the interaction between emotion and cognition.

Litt, Eliasmith, and Thagard provide an interesting account of the role of emotion in decision making. Decision-making involves the weighting of various response choices and their potential consequences. As discussed earlier in Week 6, this involves both emotional and contextual information, implicating VMPFC, amygdala, and hippocampus. The current article extends upon this and demonstrates through neurocomputational modeling how amygdala activation (representing emotional salience) influences ongoing response selection. In essence, the greater emotional arousal generated by stimuli, the greater the subjective value placed on the stimuli by the OFC. Valuations are exponentially dampened or intensified depending upon the lowered or heightened state of arousal. The authors provide equations representing this process, demonstrating how the level of amygdala activation can in essence cancel out OFC responses. Greater negative predictions elicit higher levels of arousal, and there is greater aversion to potential losses than gains in predicted outcomes. The authors go on to present fascinating accounts for the way in which framing a problem can influence decision making. Potential for loss is more arousing than potential for gain. Therefore, the way a problem is presented, emphasizing overall losses as opposed to overall gains, influences which decision is made. For example, studies by Tversky & Kahneman (1981, 1986) found when given a choice of two plans to control an outbreak expected to kill 600 people, participants were inclined to choose a plan that would result in 200 people being saved but reject a plan resulting in 400 people being killed. Objectively, both of these choices are exactly the same (200 people live, 400 people died), but when presented as an opportunity to save people the choice was more desirable than when presented with the opportunity to kill people. The same framing phenomenon occurs in the famous trolley-footbridge dilemma (Greene et al., 2002, 2004), wherein participants are more likely to chose to push a button releasing a runaway train car carrying multiple people, risking multiple peoples’ lives, than choosing to push one person in front of the runaway train, killing that person but saving the rest. Even though more people will likely die in the first option, the distance between the action of pushing a button and that action causing death is greater than the distance between making physical contact with an individual and causing death. The latter elicits far greater amygdala and OFC activation than the former, suggesting greater emotional salience. Another aspect of framing explains why people sometimes make choices that are objectively less valuable but hedonically more valuable. The authors give the example that winning $20 feels like a gain when the comparison is winning only $1, whereas winning $20 feels like a loss when the comparison is winning $100. It is objectively the same outcome, $20 is $20, but one outcome is more desirable than the other. The authors suggest the difference in desirability is the result of the distance between the actual outcome and the expected outcome. If you expect to earn $100, $20 feels like a loss. However, if you expect to win $1, $20 is a gain.
The article by Litt et al. maps well onto the article by Evans, wherein we can assume the hedonic value and emotional contribution to a decision is a result of “System 1” processes, resulting from prior learned associations and innate beliefs (such as killing another human being is bad). The degree to which the emotional aspects of a decision or reasoning process win out is related to the degree to which further elaboration and hypothesizing about a possible solution generated through “System 2” processes override System 1 contributions. Regardless, it appears we cannot “escape” bottom-up, affect-driven influences on what would otherwise be construed as a cognitive process.

Saturday, November 22, 2008

Week 7: Consciousness (Part 2)

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.

Saturday, November 15, 2008

Week 7: Consciousness (Part 1)

1 a: the quality or state of being aware especially of something within oneself b: the state or fact of being conscious of an external object, state, or fact c: awareness ; especially : concern for some social or political cause2: the state of being characterized by sensation, emotion, volition, and thought : mind 3: the totality of conscious states of an individual4: the normal state of conscious life 5: the upper level of mental life of which the person is aware as contrasted with unconscious processes

CONSCIOUS (adjective; from Latin com + scire “to know”)
1: perceiving, apprehending, or noticing with a degree of controlled thought or observation (was conscious that someone was watching) 2archaic : sharing another's knowledge or awareness of an inward state or outward fact3: personally felt (conscious guilt) 4: capable of or marked by thought, will, design, or perception5: self-conscious6: having mental faculties undulled by sleep, faintness, or stupor : awake (was conscious during the surgery) 7: done or acting with critical awareness (a conscious effort to do better) 8 a: likely to notice, consider, or appraise (a bargain-conscious shopper) b: being concerned or interested c: marked by strong feelings or notions (a race-conscious society)
synonyms see aware

This week’s two main articles were fascinating, and the stuff of mental gymnastics. What constitutes consciousness? How does consciousness emerge? What role does attention play in consciousness? It occurred to me while reading that to fully understand and consider how consciousness emerges we have to be clear about what we mean by consciousness in the first place – hence the definitions above. It seems everything from perception to controlled processing is considered “being conscious,” if we are to take the definitions above. The question seems to be, however, that if we were to take a continuum of automatic to controlled processes, wherein sensory perception falls on the automatic end and focused attention falls on the controlled end, where along this continuum would we place actual consciousness?? And what role does affect play in the generation of consciousness (or the constitution of consciousness)?? But I am getting ahead of myself somewhat…first, the readings.
Thagard, P., & Aubie, B. (in press). Emotional consciousness: A neural model of how cognitive appraisal and somatic perception interact to produce qualitative experience. Consciousness and Cognition.

In the Thagard and Aubie article, a neural model of emotional consciousness is described. The authors start by stating that any model of conscious emotional experience must be able to explain differentiation between varied emotional states; integration between varying mental processes including perception, memory, judgment, and inference; intensity of emotional arousal; emotional valence (positive or negative); and the changes or shifts from one emotional state to another. They go on to suggest emotional consciousness must not be limited to either perceptions of bodily states or cognitive appraisals of one’s state, as early emotion theorists have tended to suggest through defining emotions as either somatic perceptions or appraisals. Rather, Thagard and Aubie present a neurocomputational model in which emotional representations are comprised of both perceptions and judgments. Their model is based upon the idea that mental representations are generated not only by inputs from external or internal stimuli, but also from inputs between neural populations, such that one neural population is tuned to the firing of another neural population (out of which more complex representations arise). From this perspective, neural structures are in tune with the firing patterns of other neural structures, and these patterns of firing influence each other in a dynamic fashion. This allows for a model of parallel constraint-satisfaction, wherein the activation of one structure is constrained by the activation of another when an acceptable solution has been arrived at based upon external and internal representations.
Thagard and Aubie term this the EMOCON model of emotional consciousness. Structures implicated in this process comprise both cortical and subcortical structures: dorsolateral prefrontal cortex (DLPFC), orbitofrontal cortex (OFC), ventromedial prefrontal cortex (VMPFC), amygdala, insula, hippocampus, thalamus, ventral striatum, and raphe nucleus – structures spanning brain stem to higher cortical regions. Emotional consciousness does not result from any final output from one of these areas, but instead is an ongoing dynamic process resulting from feedback between these structures. In this way, both somatic sensations and cognitive processes are integrated, each playing a role in overall emotional consciousness. In view of the explanatory criteria mentioned above the EMOCON model satisfies each of these criteria. For example, the dynamic interaction of these structures serve to explain integration of various mental process. The strength and pattern of neuronal firing within and between neural populations serves to explain variances in intensity and valence, as well as differentiation (using a neurocomputational model, they demonstrate how the strongest emotion gains full activation and suppresses other emotions, or how two emotions can become co-activated representing mixed emotions).
Thagard and Aubie posit an important role for working memory in emotional consciousness. The current, most salient representation (including internal and external perceptions and associations from long-term memory) remains active in working memory. However, because representations in working memory decay over time, if the current representation in working memory is not further elaborated, or if attention shifts, the previously represented emotion begins to decay. The authors suggest this is what accounts for shifts in emotional consciousness or emotional change. This is an interesting idea clinically – following the EMOCO model, depressive rumination or anxious worry behavior involves continual manipulation of negative or threatening information and representations in working memory which in turn serves to perpetuate the experience of depression or anxiety. To get a better sense of the importance of this process in the maintenance or severity of depression or anxiety, it would be interesting to see if lower rates of rumination or worry are associated with poorer working memory in this population, and in turn if poorer performance on working memory tasks could predict lower symptom severity.
The article goes on to present neurocomputational models of emotional consciousness, wherein final “solutions” are arrived at through explanatory coherence. Propositions are accepted through a process whereby neurons spike in parallel causing other neurons to spark in either an excitatory or inhibitory direction until the network is stabilized, representing the final solution. However, the authors suggest emotional valence also plays an important role in the acceptance of a final solution. Emotional coherence occurs when the acceptance of a proposition is swayed by the emotional valence of that proposition, such that positive emotional valence encourages the acceptance of a proposition, and negative emotional valence encourages the rejection of a proposition. This neurocomputational model provides further evidence for the integration of both cognitive and affective processes in overall consciousness.
The take-home message of this article is: emotional consciousness is the result of the integration of perception, memory, attention, and sensation, which is further colored by emotional intensity and valence. What becomes conscious is the end result of this integration, facilitated by the manipulation of this representation in working memory. This leads to a question addressed in the second article for this week – is what becomes conscious what is attended to? Or do we attend to what is conscious?