Lecture 14: The Future of Consciousness

Question 1

What mainly raises the question whether consciousness exists in in babies?

Answer 1

Their brain is immature and has an ‘underdeveloped’ global workspace. Myelin is around the neurons and enables the communication between neurons. It speeds up the communication. It is known that myelination takes time and infants doesn’t have as much myelin as adults have. Also the frontal parts myelination is one of the latest ones to develop. So this might influence consciousness. The grey matter in early/sensory regions also develop earlier than the frontal/higher areas.

=> So global workspace is underdeveloped as they have both their myelin and the great matter not fully developed.

Question 2

How can we test consciousness in babies? (2)

Answer 2

Local Global Task in Babies

Masking Faces

Question 3

Describe the procedure and results of the local global task in babies

Answer 3

Local Global Task in babies:
This is basically the baby version of local global task (the one with xxxy). 3-month-old infants process novelty at two distinct levels:

> Violations of local expectancies: early auditory mismatch response.
Violations of global expectancies: late negative slow wave. (reminiscent of p3b)

The results are very similar to the results of adults. This suggests that hierarchical learning mechanisms are present in young infants, they are able to maintain information and learn rules. => Shows properties of consciousness.

Question 4

Describe the procedure of the masking faces study in babies

Answer 4

Babies are presented with either faces or a control trial (a scrambled face like stimulus) and their ERP (in EEG) is measured.

Question 5

Describe the results of the masking faces study in children

Answer 5

In the young kids there is no short presentation. This is because the threshold for consciousness for very young infants is higher than older infants. This means we need to present a stimulus for a longer time, because they start seeing it a bit late.

In older infants there is a clear linear difference between the amount of ms the stimulus was presented in the P400. Also an all-or-none profile for the late slow wave, regarding whether they see the face or don’t see the face. So we see two profiles: a linear wave that reflect the propagation of the stimuli and an all-or-none one that is clearly related to conscious access. We don’t see these clear patterns in younger infants. (there is no profile of global ignition).

So higher threshold of consciousness for younger infants.

Question 6

What conclusions could be drawn from the masking faces study on children?

Answer 6

Global workspace develops late in human lifespan. However, from early on babies show characteristics of global workspace process. Although this is slower (because of the lack of myelination) and the signals we measure are different than adults. For example the slow wave we measure is a negative component whereas the slow wave in adults is a positive one.

Question 7

What is the common idea regarding consciousness across species?

Answer 7

The common idea is that consciousness is a gradual phenomenon. The richness of experience changes gradually across species. When we think about monkeys etc, they do possess some level of consciousness but the richness might be less than human consciousness. So the idea is there are different levels of consciousness.

Question 8

In animals it is challenging to test consciousness and it requires smart measuring techniques. There are multiple approaches, Describe two broad categories of techniques

Answer 8

> Compare anatomy/physiology across species.

> Define what functions/behaviours are tightly linked to consciousness in humans and test which functions/behaviours are present in animals too.

Question 9

Why should we be cautious in using functions and behaviours as measurements?

Answer 9

Considering LIS, behavior is not always directly related to experience (it is often correlated but still not sure).

Question 10

Comment on atonomy across species as a measurement

Answer 10

Humans have relatively large brains. There are also several different areas, and connectivity profiles. But this is difficult to interpret because, as Dehaene also mentions in the book, we have very similar PFC but language in humans is much more developed. So it is not always easy to relate anatomy to everything.

Question 11

Describe a way consciousness was looked for in monkeys using intervention

Answer 11

We change the GNW connectivity and recurrent processing with anaesthesia and see whether the changes are similar across species.

We already talked about one, the figure ground modulation gets suppressed when monkey’s are anaesthetised, just like it happens in humans.

Also when we look at the functional connectivity when monkeys are awake vs sedated, very similar things happen as it happens to humans.

Question 12

Describe a way consciousness was looked for in monkeys through function/behaviour

Answer 12

They performed a local global task during fMRI scanning. The local novelties created more local activation while global novelties triggered a global network including the fronto-parietal cortex. This is very similar to the results in humans.

Question 13

Describe the procedure and the results of a study attempting to measure consciousness in a non-primate

Answer 13

They did a detection task, where crows indicated whether they’ve seen the stimulus by picking a ‘yes’ react or a ‘no’ react or waiting to signal either. When they graphed the results, a very similar result to humans was found. The point in this experiment is that these birds also have a two staged process with feedforward and feedback, although our brains are very different (no layers for example).

Question 14

What is the conclusion drawn regarding animals and consciousness based on these studies?

Answer 14

Based on anatomy, neurophysiology and behaviour/function profiles, it seems that the presence of consciousness if a graded phenomenon. But we don’t know where it stops.

Question 15

What is meant by meta-cognition?

Answer 15

Monitoring consciousness: Metacognition is knowledge of one’s own mental state.

Question 16

Describe the procedure of a study regarding metacognition

Answer 16

Task 1: The perceptual response indicated whether the first or second temporal interval contained the higher-contrast (pop-out) Gabor patch, which could appear at any one of six locations surrounding a fixation point.

Task 2: Confidence ratings were made using a one-to-six scale, with participants encouraged to use the whole scale from one = low relative confidence to six = high relative confidence.

They matched subjects on their Type1 performance, so on the perceptual task. They did this by stair casing the difficulty of the task. This is a technique that is used to change the differences on the contrast between the stimulus that pops out and the other stimuli in such a way that on average subjects are on 70% correct. This means that the actual input that people receive can differ, because staircase changes the contrast. So what subjects perceive are actually identical. Then what participants do in the metacognitive task, so the second task, cannot be due to the first task difficulty.

Question 17

What is meant by metacognitive ability?

Answer 17

Metacognitive ability reflects the subject’s ability to introspect their performance. The higher the value, the better we are at telling whether we were wrong or right

Question 18

What did the results of the metacognition study show?

Answer 18

Results showed that although the participants were matched on their perceptual abilities, they differed on their metacognitive performance.

Question 19

How did the researchers further investigate metacognition?

Answer 19

Researchers then investigated how much the grey matter density is related to the performance at the metacognitive task. They matched which brain regions grey matter density matched the performance (metacognitive and perceptual) the best.

Question 20

What were the results of the grey matter analysis in the metacognition study?

Answer 20

Right anterior PFC correlates with the confidence in decision, but not with d’ (task performance on the Gabor task, the perceptual task).

Question 21

They also looked at the white matter. What were the results?

Answer 21

The same result was found.

Question 22

What conclusions can be drawn from this metacognition study?

Answer 22

Therefore both the integrity of the right anterior PFC, as well as the fibre bundles connecting that specific regions with other regions of the brain correlate with metacognition.

Question 23

How did a causal study lend credence to these claims regarding metacognition?

Answer 23

Causal study with metacognition, showed that TMS over frontal cortex disrupts metacognition.

Question 24

Is metacognition uniquely human? Describe the procedure of a study which attempts to investigate this

Answer 24

A study on monkeys asked them to look at moving dots. And measured the neuronal activity of Lateral Inter-parietal Cortex. It was seen that the monkey received a pattern of moving dots. Interesting part in this experiment was that they also added a ‘blue dot’ to the screen sometimes. If monkey followed the correct red dot, he would receive a reward, if he looked at the blue dot, he would receive a smaller reward and if he looks at the wrong place, he wouldn’t get a reward at all. So it is on him to decide if he will settle for the smaller reward and avoid risking not getting a reward

(prior to the decision, a third target, called sure target, is added in some (not all) trials - if this target is selected, the reward is always the same but small (“opt out condition”) - This choice reflects the refusal to respond, which indicates the “uncertainty” or “lack of self-confidence” of the animal in the decision).

Question 25

Describe the results of the metacognition study in monkeys

Answer 25

The evidence that is present in the brain before monkey makes the decision to opt-out, already reflects the confidence in the decision. When the activity is high, the monkey has high confidence and is going to make the decision. When we look at the dotted line, it is much less strong so the monkey doesn’t have enough confidence so will use the sure-target.

Therefore monkeys have metacognition and they have introspect to decide what they are able to tell or not. Presents parietal evidence signal reflects the confidence of the monkey in the decision.