Monthly Archives: March 2015

Dehaene: Consciousness and Decision Making

consciousimagesI love Stanislas Dehaene’s experiments, his general ideas and his book:  Consciousness and the Brain:  Deciphering How the Brain Codes our Thoughts, Viking, New York 2014 is a great synthesis and with respect to the title, it is a fine book. However, with respect to how it deals with decision making, I am mostly disappointed.

Consciousness: Informer or Informer/Decider? Although Dehaene’s Global Neuronal Workspace Theory describes what we feel as consciousness as the global sharing of information, in the book he seems to promote the idea of consciousness as the decider as well as the informer. Dehaene writes:

“My picture of consciousness imples a natural division of labor. In the basement, an army of unconscious workers does the exhausting work, sifting through piles of data. Meanwhile, at the top, a select board of executives, examining only a brief of the situation, slowly makes conscious decisions…No one can act on mere probabilities–at some point, a dictatorial process is needed to collapse all uncertainties and decide….Consciousness may be the brain’s scale tipping device—collapsing all unconscious probabilities into a single conscious sample so that we can move on to further decisions.” p89

I like the informer part, but I like the parallel constraint satisfaction (post Parallel Constraint Satisfaction Theory) idea that consciousness is asked to get more information (information search and production) which the unconscious system turns into a decision. In my scenario the visual system seems to have priority to get to the conscious level, then other sensory systems, and then the other unconscious systems push the most difficult or interesting decisions they have at any particular time through to the conscious system. Maybe there is some sort of priority ranking. Clearly, most rather mundane decisions seem to break through to consciousness only occasionally. As a part of breaking through to consciousness, more of the modular systems are alerted to the issue and maybe information can come from inside or maybe we seek information from others or examine the environment. We get the new information and the wheels of the parallel constraint system start whirring again to see if the decision can be made. Now, I do see a cognitive continuum so that yes certain decisions may stay with the board of executives. Dehaene uses the example of multidigit arithmetic. For most of us, it seems to consist of a series of introspective steps that we can accurately report. For instance, to multiply 30 by 47, I might multiply 30 by 40 and get 1200 and then add it to 7 by 30 to get 1410. But for a numerical savants that could be done in the unconscious. Nevertheless, there are certain things where consciousness does seem to be where the decisions are made. Complex multi-step questions where the emotions are more or less uninvolved might be examples.

Maybe the interesting part is the sort of phase change between the unconscious and the conscious. There is a lot happening there. Dehaene says that consciousness is doing the collapsing, but it seems to me it is already done once it reaches consciousness. Maybe that is not an important argument.  One theory is that conscious perception occurs when the stimulus allows the accumulation of sufficient sensory evidence to reach a threshold, at which point the brain ‘decides’ whether it has seen anything, and what it is. The mechanisms of conscious access would then be comparable to those of other decisions, involving an accumulation toward a threshold — with the difference that conscious perception would correspond to a global high-level ‘decision to engage’ many of the brain’s internal resources. Dehaene mentions this in a paper that was discussed in the post A Theory of Consciousness.

Consciousness Gives Us the Power of a Sophisticated Serial Computer. Dehaene is a believer in the Bayesian unconscious. “A strict logic governs the brain’s unconscious circuits–they appear ideally organized to perform statistically accurate inferences concerning our sensory inputs.” Both the unconscious and conscious systems seem to work in a linear fashion (Brunswik’s Lens Model), but the conscious system can redirect.

Dehaene states:

“This seems to be a major function of consciousness:  to collect the information from various processors, synthesize it, and then broadcast the result–a conscious symbol–to other, arbitrarily selected processors. These processors, in turn, apply their unconscious skills to this symbol, and the entire cycle may repeat a number  of times.  The outcome is a hybrid serial-parallel machine, in which stages of massively parallel computation are interleaved with a serial stage of conscious decision making and information routing.” p100

Dehaene and his colleagues have studied schizophrenics. They found a basic deficit of consciousness perception in schizophrenia. Words had to be presented for a longer time before schizophrenics reported conscious seeing. “Schizophrenics’ main problem seems to lie in the global integration of incoming information into a coherent whole.” Dehaene suggests that schizophrenics have a “global loss of top-down connectivity. This loss impairs capacity for conscious monitoring, top-down attention, working memory, and decision making. Apparently in schizophrenics, the prediction machine is not making enough predictions. With reduced top down messages, sensory inputs are never explained and error messages remain triggering multiple explanations. Schizophrenics thus see the need for complicated explanations that can lead to the far fetched interpretations of their surroundings that may express themselves as bizarre hallucinations and delusions.

Dehaene suggests that consciousness allows us to share information with others and that leads to better decisions. Dehaene’s most interesting idea is that our social abilities allow us to make decisions together and that these are better decisions. Although one can argue that language is imperfect and that much of it is used to transmit trivia and gossip, Dehaene provides evidence that our conversations are more than tabloids. This is a point that needed to be made to me. I was tending to believe that there was almost a direct tradeoff between cognitive skills and social skills and even though that tradeoff was adaptive, maybe it was close. Dehaene puts forth the argument that two heads are better than one and that consciousness makes this possible (This is also directly in line with Scott Page’s: The Difference — How the Power of Diversity Creates Better Groups, post Diversity or Systematic Error).

He cites the experiments of Iranian psychologist Bahador Bahrami. Bahrami had pairs of subjects examine two displays and were asked to decide on each trial whether the first or second contained a near threshold target image. The subjects initially made the decision independently and if they differed were asked to resolve the conflict through a brief discussion. As long as the abilities of the individuals were similar, pairing them yielded a significant improvement in accuracy. Nuances were not was shared to gain this, but simply a categorical answer (first or second display) and a judgment of confidence.

Dehaene suggests that Bayesian decision theory tells us that the very same decision rules should apply to our own thoughts and to those that we receive from others. In both cases, optimal decision making demands that each source of information, whether internal or external, should be weighted as accurately as possible, by an estimate of its reliability, before all the information is brought together into a single decision space. This sounds much like cue validities in Brunswik’s lens model or Parallel Constraint Satisfaction theory. According to Dehaene, once this workspace was opened to social inputs from other minds, we were able reap the benefits of a collective decision making algorithm: by comparing our knowledge with that of others, we achieve better decisions.







Slippery slope hypocrites

hypocrisy7187159178399176This post looks at a paper, “Rational Hypocrisy: A Bayesian Analysis Based on Informal Argumentation and Slippery Slopes,” Cognitive Science 38 (2014) 1456–1467, written by Tage S. Rai and Keith J. Holyoak (posts Metaphor, Bidirectional Reasoning) that draws a connection between what may look like moral hypocrisy and the categories we select for cases with weak arguments by looking at the slippery slope argument. Moral hypocrisy is typically viewed as an ethical accusation: Someone is applying different moral standards to essentially identical cases, dishonestly claiming that one action is acceptable while otherwise equivalent actions are not. The authors provide the following example:

“I respect the jury’s verdict. But I have concluded that the prison sentence given to
Mr. Libby is excessive.” With these words, former President George W. Bush commuted
the sentence of I. Lewis “Scooter” Libby, Jr., for obstruction of justice and leaking the
identity of CIA operative Valerie Plame. Critics of the decision noted that Libby had actually received the minimum sentence allowable for his offense under the law and that many of Libby’s supporters, including the Bush administration, were actively pressing for mandatory minimum sentencing laws at a national level. Accordingly, critics of the decision saw it as a textbook case of moral hypocrisy: Different rules were being applied to Bush’s underling, Libby, than to everyone else in the United States.

The implicit assumption is that the hypocrite is being dishonest, or at least self deceptive, because the hypocrite must be aware (or should be aware) of the logical inconsistency and is therefore committing a falsehood. Rai and Holyoak have extended the analysis of Corner et al concerning slippery slope (post Slippery Slope) arguments to moral hypocrisy and suggest that the alleged hypocrite may be both honest and rational.

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Slippery slope

slippery-slopeThis post is  based on: “The Slippery Slope Argument – Probability, Utility & Category Reappraisal,” written by Adam Corner, Ulrike Hahn, and Mike Oaksford and included in the 2006 Cognitive Science Conference Proceedings in the Cognitive Science Journal archive. The authors say that it is usually classified as a fallacy of reason, yet frequently used and widely accepted in applied domains such as politics, law and bioethics. They note that the slippery slope argument remains a controversial topic in the field of argumentation, and possesses the somewhat undignified status of “wrong but persuasive”. Having been a part of political and legal decisions, the slippery slope is ever present in my experience, although I never thought of it as a fallacy. Thinking about it though, it is what you tend to use when you think that you are going to lose the argument. I think it is interesting that every day people do not only use the technique, but they usually label it as a slippery slope which I guess shows what a powerful metaphor it is. I was also unaware that there is a “field of argumentation.”

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Screen-Shot-2015-01-23-at-2.30.26-PMThis post is based on the paper: “The discovery and comparison of symbolic magnitudes,” written by Cognitive Psychology 71 (2014) 27–54 This is a little different from one of Brunswik’s ideas –how good we are at determining sizes in the environment. Those might be called perceptual magnitudes. Symbolic magnitudes seem to be ones taken from memory and the immediate context.

We have sophisticated abilities to learn and make judgments based on relative magnitude. Magnitude comparisons are critical in making choices (e.g., which of two products is more desirable?), making social evaluations (e.g., which person is friendlier?), and in many other forms of appraisal (e.g., who can run faster, this bear or me?). In the paper, the authors seek to explain where subjective magnitudes come from?

For a few types of symbolic comparisons, such as numerical magnitudes of digits, it may indeed be the case that each object has a pre-stored magnitude in long-term memory.  The notion that magnitudes are pre-stored is implausible for the wide range of dimensions on which people can make symbolic comparisons, especially in the interpersonal and social realm (e.g., intelligence, friendliness, religiosity, conservatism). Magnitudes are more likely derived, context-dependent features that are computed as needed in response to a query.

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Parameter P- Slowness Factor?


This post looks at Parameter P, a specific construct of the PCS-DM model, as elaborated in “What is adaptive about adaptive decision making? A parallel constraint satisfaction account,” by Andreas Glöckner, Benjamin E. Hilbig, and Marc Jekel (Cognition 133 (2014) 641–666). (See post Revisiting Swiss Army Knife or Adaptive Tool Box.)

Glockner et al state that transformations in Eqs. (3)–(5) (See figure at top of post.) are commonplace and sensitivity analyses have shown that the selection of specific values has little influence on predictions as long as inhibitory connections are relatively strong compared to excitatory connections. PCS-DM predictions, however, strongly depend on Eq. (2). In this equation for calculating connection weights, validities are corrected for chance level (.50) to avoid that irrelevant cues have a weight. Parameter P allows PCS-DM to capture individual differences in the subjective sensitivity to differences in cue validities. Low sensitivity is captured by low P. By contrast, high sensitivity for cue validities is captured by large values of P with high values as special cases in which less valid cues cannot overrule more valid ones. P captures sensitivity at the level of individuals, that is, it determines how an individual transforms explicitly provided or learned information about a cue’s predictive power (i.e., cue validity) into a weight. Glockner et al suggest that P describes a core property of a psychological transformation process that precedes decision making.

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