Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience

Cognition, Brain and Consciousness: An Introduction to Cognitive NeuroscienceEdited by Bernard J. Baars and Nicole M. Gage2007 Academic Press

Chapter 10 Thinking and Problem Solving

“Recruitment of executive attention is normally associated with a subjective feeling of mental effort.”

Lionel Naccache, Stanislas Dehaene, Laurent Cohen, Marie-Odile Habert, Elodie Guichart-Gomez, Damien Galanaud, and Jean-Claude Willer, 2004


Chapter Outline

1.0 Working memory

2.0 Explicit problem solving

3.0 Mental workload and cortical activity

4.0 Using existing knowledge

5.0 Implicit thinking

6.0 Summary



Human problem-solving comes in two varieties: explicit and implicit.

These two modes differ sharply: explicit problem-solving has clear, conscious goals and clearly defined steps for getting from a starting point to a solution.

Mental arithmetic is an example of explicit problem-solving.



Human problem-solving comes in two varieties: explicit and implicit.

Implicit problem-solving may be more common than explicit since we learn and practice many kinds of skills from early on in life. These problem-solving skills become more proficient, implicit (unconscious), and automatic with practice.

Infants acquiring language is an example of implicit problem-solving.



Explicit problem-solving involves greater executive control, higher mental workload, more frequent conscious access, and wider recruitment of cortical regions in pursuit of explicit goals.

Implicit problem-solving takes less executive control than the explicit kind, less conscious access, lower cognitive load, and less cortical involvement.


1.0 Working Memory

Working memory in the functional framework

Working memory is constantly involved in problem-solving, however working memory functions also make use of stored information shown in the gray boxes at the bottom of the functional framework diagram.


1.0 Working Memory

A schematic of brain areas in the frontal and parietal lobes that support working memory processes.


1.0 Working Memory

Brain regions supporting working memory overlap with those supporting attention, conscious events, and episodic recall. This widespread activation primarily includes frontal and parietal cortex.


2.0 Explicit Problem Solving

Problem-solving can be thought of as finding a path through a maze of choice-points between possible sub-goals toward a final goal. A puzzle called the Towers of Hanoi is frequently used to investigate brain areas involved in explicit problem-solving. The task is to move the disks between the rods, one step at a time, until that they match the goal.



Brain areas activated during solving of the Towers of Hanoi include the dorsolateral prefrontal cortex.



Flexibility is an important aspect of successful explicit problem-solving. People may get ‘fixed’ in problem-solving strategies: a standard task used to investigate flexibility in problem-solving strategies is the Wisconsin Card Sorting Task (WCS).

The basic task is for the subject to sort cards, however they are not instructed as to what the rules are for sorting -- they must extract the rules based on experimenter feedback regarding whether their sorting is correct or not.



WCS: possible rules are to sort by color, number, or shape. To be successful, the subject must be ready to switch his task from, for example, sorting by color to sorting by shape based on feedback from the experimenter.



Brain areas involved in adapting to new rules -- or task switching -- overlap with areas active for other executive tasks in frontal and parietal lobes.



A current model for brain areas involved in explicit problem-solving: on the outer surface of each hemisphere, peak activity during problem-solving appears in the dorsolateral prefrontal cortex (DLPFC).

During task conflict or errors, we find high activity in the forward (anterior) part of cingulate cortex (ACC).


3.0 Mental Workload and Cortical Activity

Effortful tasks show a wide spread of brain activity, even beyond the executive regions of the frontal cortex.

In a classic fMRI study by Smith and Jonides, memory load was varied using an n-back task. In this task, the subject must hold in mind several trials in order to report the item that was presented in the n-preceding trials.


3.0 Mental Workload and Cortical Activity

Effortful tasks show a wide spread of brain activity, even beyond the executive regions of the frontal cortex

Results showed a dramatically expanded cortical activity as a function of memory load.


4.0 Using Existing Knowledge

Interactivity of short- and long-term stores

While working memory functions are typically thought of as dealing with inputs to the cognitive system, it is important to note that working memory systems interact constantly with long-term stores as well as with incoming information.



Working memory constantly activates long-term storageCowan (2001) suggests that working memory may be thought of as active and time-limited neuronal activity playing on long-term patterns of structural connectivity.



Semantic memory plays a key role in problem-solving. How and where are concepts represented in the brain?

A recent summary of semantic memory location in the left hemisphere provides evidence that semantic working memory involves constantly looping activity between the temporal and frontal lobes.



Abstract concepts, prototypes, and networks

How is semantic knowledge represented in the brain? Do we carry pictures in our heads that represent the perceptual world around us? Evidence suggests that we tend to use visual images that are prototypical reminders of categories like chair or movie star.



Knowledge comes in networks

Mental representations, including words, concepts, and images, are thought to be organized in the brain in elaborate networks of knowledge.

Ideas appear to be represented in the cortex in terms of complex webs of learned connectivities, rather than localized filing systems with neatly arranged conceptual categories.

Overlapping semantic networks for concepts ‘tiger’ and ‘elephant’.



Conceptual deficits

Some of what we have learned about cortical representation of concepts comes from patients with brain damage in regions that are involved in semantic memory and conceptual representation.

The specific deficits that these patients have following brain damage informs us as to the role of those brain regions in semantic memory.



Conceptual deficits

Patient EW had a deficit in naming animals but not in naming members of other categories, such as faces.

Her deficits were not only in recognizing pictures of animals, but also in recognizing spoken animal names, indicating that visual and sound representations of animals might be located in the same brain areas.

The fact that her deficit was limited to the animal category indicates that different semantic categories -- like animals and faces -- may be stored in differing brain regions.



Judgments of quantity and number

Is there a network for number judgment?

To the surprise of many, good evidence has emerged recently for specific areas of parietal cortex for number naming and number judgments.


5.0 Implicit Thinking

Most human problem-solving is a mixture of explicit and implicit ingredients. We tend to underestimate the complexity of implicit cognition -- precisely because it is unconscious. In fact, it is our highly expert, overlearned habits that may be the most efficient tools for solving problems.

Sudden insight in problem-solving is likely due to implicit processes at work at the task. EEG studies have shown that just before making a correct response, alpha density decreases and gamma increases. Gamma activity is thought to reflect active and synchronized processing in neural networks across the brain.


6.0 Summary

Working memory is the domain of problem-solving

Completely explicit problem-solving is probably rare in the natural world

Explicit puzzles like the Tower of Hanoi are quite sensitive to frontal lobe damage; the WSC task can be used to test for mental flexibility in problem-solving

Effective problem-solving likely entails a mixture of explicit and implicit processes along with a high degree of mental flexibility

Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience

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