Wednesday, November 12, 2008

Decision-making research in autism and schizophrenia: Implications for each other

Today I would like to review two recent articles on decision-making: one concerned with autism or ASD and the other with Schizophrenia individuals. I would like to demonstrate how some of the findings fit in, in the larger context of Autism and Schizophrenia as diametrical poles on a continuum.

The first article is by Martino et al, and discusses a finding that those with ASD display more consistent and logical decision-making that is immune to framing effects.  Here is the abstract of the study:

The emotional responses elicited by the way options are framed often results in lack of logical consistency in human decision making. In this study, we investigated subjects with autism spectrum disorder (ASD) using a financial task in which the monetary prospects were presented as either loss or gain. We report both behavioral evidence that ASD subjects show a reduced susceptibility to the framing effect and psycho-physiological evidence that they fail to incorporate emotional context into the decision-making process. On this basis, we suggest that this insensitivity to contextual frame, although enhancing choice consistency in ASD, may also underpin core deficits in this disorder. These data highlight both benefits and costs arising from multiple decision processes in human cognition.

Here is the introduction:

Logical consistency across decisions, regardless of how choices are presented, is a central tenet of rational choice theory and the cornerstone of modern economic and political science. Empirical data challenge this perspective by showing that humans are highly susceptible to the manner or context in which options are cast, resulting in a decision bias termed the "framing effect". We have previously shown that the amygdala mediates this framing bias, a finding that highlights the importance of incorporating emotional processes within models of human decision making. An ability to integrate emotional contextual information into the decision process provides a useful heuristic in decision making under uncertainty. This is a factor that is likely to assume considerable importance during social interactions in which information about others is often incomplete, ambiguous, and not easily amenable to standard inferential reasoning processes.
In this study, we investigated the effect of contextual frame on choice behavior of individuals with autistic spectrum disorder (ASD). Autism is a neurodevelopmental disorder characterized by deficits in social interaction, qualitative impairments in communication, and repetitive and stereotyped patterns of behavior, interests, and activities. From Kanner's earliest description, it has been recognized that individuals with ASD have a strong tendency to focus on parts rather than global aspects of objects of interest and are unable to integrate disparate information into a meaningful whole (weak central coherence theory).
We previously proposed that susceptibility to a framing bias reflects the operation of an affect heuristic. Here, we show that individuals with ASD, a condition characterized by marked behavioral inflexibility, demonstrate a decreased susceptibility to framing resulting in an unusual enhancement in logical consistency that is paradoxically more in line with the normative prescriptions of rationality at the core of the current economics theory. Furthermore, insensitivity in these subjects to a contextual framing bias was associated with a failure to express a differential autonomic response to contextual cues as indexed in skin conductance responses (SCRs), a standard measure of emotional processing. Our findings suggest that a more consistent pattern of choice in the ASD group reflects a failure to incorporate emotional cues into the decision process, an enhanced economic "rationality" that may come at a cost of reduced behavioral flexibility.


The experimental procedure used framing of gambles in terms of loss and gain and it is a well established paradigm that shows that normal people are risk-averse when the same gamble is framed in gain terms and risk-prone when the same gamble is framed in loss terms. Autistcis were not only more risk-averse in general , but their responses did not differ in relation to whether the frame was of loss or of gain. Thus, they were consistent in both the framing conditions. also , a measure fo their skin conductance did not show differential activation in the two frames of loss and gain; while the SCR of controls differed significantly. thus, teh authors conclude that it is the inability to take into account emotional information, that results in the consistent response of the autistics.Here is the discussion:


These findings suggest the ASD group fail to integrate emotional contextual cues into the decision-making process. This is evident both in a reduced behavioral susceptibility of a framing effect and an absence of a differential SCR response to our contextual manipulation. The concept that ASD individuals fail to integrate information across cognitive domains also informs the suggestion that an uneven profile of abilities and deficiencies in autistic individuals may reveal an imbalance in empathizing and systemizing behaviors (Baron-Cohen and Belmonte, 2005)


They discuss these findings in terms of the two-system theory of decision-making and here is what they have to say:

Recent theoretical accounts of decision making have put forward a "two-systems" model of human judgment (Evans, 2003). This view proposes that human decision making arises through a combination of intuitive and analytic processes. This model proposes that intuitive reasoning is rapid and capable of processing large amounts of information in parallel; however, it is prone to mistakes and strongly influenced by contextual emotional information (Kahneman, 2003). In contrast, analytical reasoning is more accurate but slow and computationally demanding. According to this view, the framing bias reflects an affect heuristic by which normal individuals incorporate a potentially broad range of additional emotional information into the decision process. In evolutionary terms, this mechanism may confer a strong advantage because such contextual cues may carry useful, even critical, information that dictates a rapid response. We propose that this ability is particularly crucial in a social context in that subtle contextual cues communicate knowledge elements (possibly unconscious) that allow optimal decisions to be made in uncertain environments (Stanovich and West, 2002).
In the context of the "two-systems" model of decision making described above, these results suggest that ASD individuals have an increased tendency toward the analytic type of decision making, attributable to impairment within their intuitive reasoning mechanisms. This interpretation would also support the empathizing-systemizing (E-S) theory of autism (Baron-Cohen and Belmonte, 2005). The E-S theory proposes that the imbalance between analytic and empathic behavior underlies both the impairment in social skills in ASD and their enhanced analytical skills. During the framing task, ASD subjects were better able to ignore biasing contextual information and isolate the critical information about the numerical value of the sure and risky options. This result is consistent with other experimental findings showing that ASD have enhanced attention for the task's details but reduced capacity to deal with the global aspect of the task as predicted by weak coherence theory (Frith and Happé, 1994).

Now, I am just overjoyed reading the above. It has always been my contention that Autistics use a more deliberate, rational approach to decisions while schizophrenics are at the opposite end relying on the intuitive part. I elaborated it in the form of Maximisers and Satisficers distinction that Barry Scwatrz has proposed and extended it to include exploration and exploitation in general. In short my thesis was, and remains, that autistics are more analytical while decision-making and schizophrenics more intuitive . the former does not take the context or frames into account while making decisions while the other takes into account too much context and is susceptible to too much framing effects.

If the above thesis is correct it leads to many testable predictions:

  • 1) Schizophnrenics/ Schizotypal individuals should be more susceptible to framing effects and should show greater inconsistencies in decision-making under uncertainity as compared to controls.
  • 2) They may also show more SCR variability when different frames of loss and gain are presented to them as compared to controls.
  • 3) They may have higher baseline risk-prone behavior than controls in all conditions.
  • 4) They may have higher activation in amygdala than controls as they use affect heuristic quite frequently while making decisions.


Part of this prediction may be satisfied by this decision-making and schizophrenia study by Ludwig et al  that found decision-making dysregulation in first episode Schizophrneia patients. Here is the abstract of the study:

Studies with chronic schizophrenia patients have demonstrated that patients fluctuate between rigid and unpredictable responses in decision-making situations, a phenomenon which has been called dysregulation. The aim of this study was to investigate whether schizophrenia patients already display dysregulated behavior at the beginning of their illness. Thirty-two first-episode schizophrenia or schizophreniform patients and 30 healthy controls performed the two-choice prediction task. The decision-making behavior of first-episode patients was shown to be characterized by a high degree of dysregulation accompanied by low metric entropy and a tendency towards increased mutual information. These results indicate that behavioral abnormalities during the two-choice prediction task are already present during the early stages of the illness.

The authors used the CT paradigm and it is important to explain that a bit here:

The purpose of the CT is to quantify decision-making characteristics based on the individuals’ sequential response patterns, which result from repeated selections of different alternatives associated with an uncertain outcome. Each subject received computerized instructions. The subject’s task is to predict on which side a stimulus (a car on the screen) will appear and select a response (to match up one of 2 figures shown on the screen) accordingly. The outcome is shown for 250 milliseconds after the subject has selected as response. A new trial begins immediately after the car has been displayed. The subject is not given any information about the sequence of the stimulus presentations, i.e., whether the stimulus is presented randomly or in any kind of order. Unbeknownst to the subjects, the location of the car shown is based on the subject’s response, i.e., the subject “correctly” predicts the location of the car in 64 trials. The basic measurements consist of the subject’s response, the presentation of the car and the latency of the response selection process, i.e., the time from the beginning of the trial to the pressing of the button. For the behavioral analysis, we used nonlinear methods— described elsewhere in detail (Paulus et al., 2001)—to obtain the following key measures:
Dysregulation: Dysregulation quantifies the range of response sequence entropies during the course of an experiment.A high dysregulation value indicates that the response sequences occurring during the experiment are characterized by botho¨perseverative tendencies“ and highly unpredictable or dynamically ”chaotic” strategies.
Metric entropy: Entropy measures the “sequential order” within sequences of responses. Whereas low entropy indicates that the response sequences are highly predictable, high entropy implies highly unpredictable response sequences. Thus, predictability is a collateral measure for the degree to which sequences of responses are based on a consistent internal strategy. However,this measure does not take into account the dependence of the response sequence on external stimuli, which is measured by the cross-mutual information (see below).
Mutual information: Mutual information quantifies the degree to which the previous response predicted the current response and provides a measure of the immediate influence of the past response on the decision in the current trial.
Cross-mutual information: Cross-mutual information quantifies the degree to which the previous location of the stimulus (presentation of the car on the LEFT or RIGHT hand side) is able to predict the current response. As opposed to entropy and mutual information, this measure quantifies the influence of external stimuli on the response sequences.
Switching probability: the probability of using the simple strategy RIGHT – LEFT.
Reaction time: the time between stimulus and response.

What they observed is summarized below:

As shown above in the results section, first-episode patients performing this decision-making test, irrespective of whether they were unmedicated or recently medicated, can be observed to have (a) more dysregulated behavior, (b) a reduced metric entropy, and (c) a tendency towards increased mutual information. As a specific response behavior (d), the patients used the switching strategy more intensely (switching between pushing the right and the left button). This study has supported our main hypothesis that decision-making dysfunctions are already present in first-episode schizophrenia (or SZ) patients.

I believe the results need some explanation, and I will stick my neck out here. More dysregulated behavior in my view, is due to the schizophrenic either trying too hard to remain consistent (when in self-aware frame of mind) or trying to be unpredictable (when in other-aware and being-watched frame of mind). The reduced metric entropy can be explained similarly . Tendency towards increased mutual information is quite informative in my view. It seems that the schizophenreic is working on the basis of an internal model and is ignoring external feedback: thus his reliance on previous response.I propose that an opposite pattern would be observed in Autistics with Autistics showing no or less mutual information, as they have poor self-models; but greater cross-mutual information , as they would base their decisions more on external stimuli or feedback.

Some other predictions, keeping in mind the autism is opposite of Schizophrenia theory are:

  • 1) Autistcis should show lesser dysregulation and more rational behavior than even controls.
  • 2) autistcis should show greater cross-mutual information than controls.
  • 3) Autistcis may or may not show lesser mutual information.
  • 4) Autistcis should use less switching strategy than controls.

All these are testable predictions and I hope someone out there tests these and lets me know!
ResearchBlogging.org
B. De Martino, N. A. Harrison, S. Knafo, G. Bird, R. J. Dolan (2008). Explaining Enhanced Logical Consistency during Decision Making in Autism Journal of Neuroscience, 28 (42), 10746-10750 DOI: 10.1523/JNEUROSCI.2895-08.2008
Cattapan-Ludewig Katja; Ludewig Stephan; Messerli Nadine; Vollenweider Franz X; Seitz Antonia; Feldon Joram; Paulus Martin P (2008). Decision-Making Dysregulation in First-Episode
Schizophrenia The Journal of nervous and mental disease, 196 (2), 157-160

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3 comments:

Neuroskeptic said...

The Martino et. al. study is very interesting - although I have to say, the findings don't surprise me!

I wonder how people with mPFC damage, like Phineas Gage, would perform on that task - if you read Damasio's account of mPFC lesion patients, they are very deliberate and "rational" in their decision making, to the point of being unable to actually commit to any choices. Although they can also show hyper-emotionality in other situations.

Also, on another note, I know you're interested in the neurogenesis theory of depression and antidepressants. I thought you might like a post I made here.

Neuroskeptic

Sandy G said...

Hi Neuroskeptic,

The findings of Martino et al, didn't surprise me either, but they are important as they fit in the broader framework.

The antidepressant and neurogeneisis article on your blog is truly great and I found it very useful. I've subscriber to the feed and hope to read more of your wonderful blog!

Azkyroth said...

I saw this study's abstract; my take on it: While I can see why this ability would cause friction with the neuromajority, I am absolutely in awe of the level of mental gymnastics needed to straight-facedly characterize reduced susceptibility to emotional manipulation as a "deficit" or "failure."