User talk:Hakwan Lau/Proposed/Awareness of intention
COMMENTS FROM REVIEWER B
This article addresses a question which is at the frontiers of contemporary science. It is also of major importance because the answers are liable to interest scientists and philosophers but also jurists and politicians. Therefore it is very important to carefully describe this topics. Writing an encyclopedic review is a task which requires to synthesize the current knowledge. It becomes harder when its diffusion has a high impact like that of Scholarpedia.
Because this reviewer has had a hard time to read this article, the authors are encouraged to read it again (after a while for "resetting their mind") and write it in a simpler manner. Otherwise, it is very likely that very few persons will read or refer to this article. Below are some of the major reasons which made this article difficult to read. The first reason is the frequent use of different words for designating the same phenomemon (semantic problem). The second and related reason is the lack of definitions (e.g. no definition of intention). The third reason is the presence of contradictions which force the reader to read back and forth different chapters/paragraphs and which emphasize the semantic problems. The fourth reason is due to repetitions: one finds descriptions of experiments in different chapters. Some chapters are rather poor (e.g. Cued intention) and certainly do not look encyclopedic (e.g. Ownership of action). Concerning this last issue, this reviewer considers that this chapter concerns what is called "Sense of Agency" by several authors. The authors' chapter mostly describes experiments that were performed by Wergner and colleagues and completely neglects all the remaining literature and related works. Moreover, the rationale of this paragraph in the context of "awareness of intention" is not clearly exposed.
The tone taken in the reviewer's comments may sometimes sound sharp. But the authors can be ensured that those comments were made to help the authors to upgrade their article.
Discovery of in the readiness potential (RP)
Figure 1: Does time 0 correspond to movement onset or to EMG onset? What type of movement was produced during this RP recording?
1) Please explain why the RP is a discovery which is 1) surprising and 2) related to the awareness of intention.
2) In the abstract, Kornhuber and Deecke (1965) do not refer to "finger movements" but to hand or foot movements. Please check your reference.
3) For clarity, the authors should avoid using several different terms for designating the same phenomenon. Here are a few examples where the authors use different formulas for apparently the same thing: -"voluntary movements" -"self-paced" (can't self-paced movements be involuntary?) -"spontaneously initiated action" -"endogenously generated action" -"spontaneous self-paced movements" Can we define "action" as "a movement which is preceded by an intention"?
4) Because time is an important aspect of EEG signals, the authors should be more accurate in their sentence “whose onset occurs roughly one second before a spontaneously initiated action”. Please give a range of values. According to figure 1, if time 0 corresponds to movement onset, the onset of the RP occurs approximately 500 ms before movement onset.
5) Please add a reference for the sentence: “The exact onset time of the RP depends on the nature of the task being performed”.
6) I suggest removing the sentence: “but it is always earlier than one would otherwise intuitively expect”. It is unclear what the authors mean or what the common sense (“one”) would intuitively expect.
7) Please remove “spontaneously” and “spontaneous”. Some movements can be produced “spontaneously” without being “voluntary” or “self-paced” (e.g. eye blinks, saccades).
8) The sentence “one seems to perform spontaneous self-paced movements without much awareness of their preparations, but the brain somehow seems to be preparing these for a much longer time” is problematic in several aspects. Please rephrase it. First, it seems to differentiate the brain and the acting subject. I suggest replacing it with “one seems to perform self-paced movements without much awareness of either their preparations or the associated changes in brain activity”. Second, the authors suggest that movement preparation last for a longer time. Longer than what? Is it possible to estimate the duration? Do the authors suggest that a backward masking of the preparatory activity by the movement-related activity (or reafferent sensory signals)?
9) The authors should read again their sentence. The message is that the RP is the “first evidence that endogenously generated actions are preceded and perhaps initiated by neural activity”. Do the authors mean that before these recordings by Kornhuber and Deecke in 1965, it was unclear whether changes in neural activity could be responsible for the generation of movements, whether endogenously generated or sensory triggered? What do think the authors about the contributions from the numerous past studies describing the effects of electrical stimulation or the consequences of lesions? Is it possible that endogenously generated actions are preceded by something else than neural activity?
10) It would be useful that the authors give a reference supporting the idea that RP are observed irrespective of the type of movement which is being prepared. Are RP also present prior to lid movements? If so, lid movements would be very interesting to study because they can be voluntary generated, triggered by sensory stimuli and "spontaneous" (to avoid corneal dryness).
12) the authors could refer to a recent extensive review on BP by Shibasaki H and Hallett M. (2006).
Line 1 : Deecke and Kornhuber (1965) replaced with Kornhuber and Deecke (1965).
Line 8 : Deecke and Kornhuber replaced with Kornhuber and Deecke.
Line : “They named this event-related potential the bereitschaftspotential (German), also known subsequently as the readiness potential, and BP or RP for short. The RP (as mentioned above) is a slow…” replaced with “They named this event-related potential the Bereitschaftspotential (BP), also known subsequently as the readiness potential (RP). The RP is a slow …”
Characteristics of the RP
This paragraph looks like a list of experiments. Each paragraph could be introduced by a simple sentence summarizing the point raised by the experiments, i.e.
1) the first paragraph seems to indicate that RP are not observed only during self-paced movements but also during movements triggered by visual events.
2) the second paragraph indicates that the RP is not movement-related. Please indicate which paper is concerned. The reference list contains two papers by Libet et al (1983).
3) The third paragraph introduces the concepts of “awareness” and “conscious intention”. According to Keller and Heckhausen, a movement is defined as a “consciously intended spontaneous movement” if the subject is able to say whether he was “aware of an urge to move before moving”. Otherwise, the movement is defined as “unconscious”. The existence of a RP does not permit to distinguish between these two types of movements. It is not an electrophysiological marker of conscious intention. Many readers will not understand what the authors mean with “more focused along the midline”.
4) The conclusion that “the RP indexes a process of preparation for endogenously generated action” looks incomplete. Indeed, it does not seem to be compatible with the results from Libet et al (1983) which suggest that RP also appears during movements triggered by visual events?
Libet’s clock paradigm: RP precedes intention
Same remark as above about the reference Libet et al (1983). Please indicate which paper is concerned. The reference list contains two papers by Libet et al (1983).
The sentence "the RP may need to reach a certain intensity for us to become aware of our intentions" is odd. To this reviewer, it sounds like saying that "the ECG may need to reach a certain frequency for us to become aware of our heart rate". Awareness is not built upon measurement parameters but upon physiological mechanisms.
The readers will have hard time understanding the experiment by Libet et al (1983) as described in the first paragraph. The description is the following: 1) subjects view a clock and wait; 2) after one full revolution of the dot in the clock, they are allowed to perform a well-defined finger movement.
What is unclear is what triggers the movement? The urge to move? Is this urge triggered by the clock? The sentence “whenever the urge to move spontaneously arose” is difficult to understand because of the word “spontaneously”. Is this word necessary ? What is the purpose of using a clock? Please rephrase it.
Moreover, it seems that some information is missing. Did the subjects report “earliest time at which they felt an urge to move” and the “time at which they actually did move” in separate blocks of trials? What determined which report they had to make? Is there any difference between “the onset of intention” and the “time at which the decision to move is made?
The third paragraph is very difficult to understand. In the first sentence, “Libet interpreted these results to mean that…” replaced with “According to Libet,…”. The complete sentence (“Libet … mean that conscious intention is not causally responsible for initiating movements”) contradicts the first sentence in the next chapter entitled Doubt about the conscious veto (“he argues that they [Libet’s findings] were consistent with intention playing the causal role of deciding …”). Similarly, the third sentence (“conscious intention having a causal role”) seems to contradict the first one (“conscious intention is not causally responsible for initiating movements”). “Causal role” for what?
What does the following sentence mean: “Conscious processes … could determine whether the unconsciously initiated movement would ultimately find behavioral expression”. This sentence implies that an unconsciously initiated movement may not find “behavioral expression”. What does “behavioral expression” mean? Does "behavioral expression" correspond to the observed movement? If so, what are "unsconciously initiated movements"? Movements that subjects are not aware of doing? Are these arguments from Libet or from the authors? What are the "cerebral precursors of movement"? RP onset? If so, replace with RP onset and indicate that RP onset precedes intention onset. But, in the begining of the paragraph, it is indicated that "RP may need to reach a certain intensity ... to become aware of our intentions". What is the relation between RP onset and threshold crossing ? Is this threshold crossing the "cerebral precursors of movement"?
Conscious processes may exert an inhibitory control over unconsciously initiated behavior (conscious veto) but what for? For reporting experience? Does this “conscious veto” happens before movement onset or after movement is finished?
Doubt about the conscious veto
The first sentence is very difficult to understand and should be re-phrased. There is some oddity in "deciding which unconsciouly initiated movements ultimately found behavioral expression". See above.
The authors now start using the word "action" instead of "movement". Why? Do they consider these two words have the same meaning?
Third paragraph, last sentence: this reviewer did not understand the logic of this sentence. Some argument must have been omitted. Please re-phrase. Second and third paragraph were clear up to this point.
Fourth and fifth paragraph: use of a new terminology: "intention experience". What is it? Judgement about "intention onset"? Isn't this judgment given well after the movement? Is it possible that the alteration in judging "intention onset" is due to some backward masking effect of the TMS, to some perturbation in verbal report or in working memory? How can "experience of intention" have causal role over something (behavior=movement?) which happened slightly before unless "experience of intention" and "movement" are independently generated? Moreover, this reviewer is not sure about the rationale of the TMS experiment. 1) Is there any reason why the judgment about intention onset would not be "contructed" from "RP onset" (or "LRP onset") or "threshold crossing" and the time when the subject gives his verbal report? 2) Assuming that intention onset emerges at time T from some cortical activity somewhere in area A, should not a TMS over area A at time T remove the ability for subjects to estimate intention onset? Has this putative area been located? Does time T correspond to RP (or LRP)onset?
Neural correlates of intention
What is figure 2 supposed to illustrate? A legend may be useful to the reader.
First paragraph, with "spontaneous actions", do they mean "self-generated actions"? This remark hold for the complete document.
It would be useful that the reader explain how Thaler et al (1995) trained their monkeys to make spontaneous movements.
Is there any clinical studies showing impairment in making "spontaneous" movements in some brain lesioned patients. Is the idea of SMA as a neural generator for the readiness potential been corroborated by studies in patients with SMA lesion?
This paragraph comes too late. Readers will have to read 5 paragraphs (out of 8) to discover the "type of intention focused in this article". This can be annoying to some readers.
Second paragraph: please define what is the "baseline condition".
Is the work by Haggard et al (2002) the only available work about this topics ?
Ownership of action
This reviewer considers that this chapter concerns what is called "Sense of Agency" by several authors. It mostly describes experiments that were performed by Wergner and colleagues and completely neglects all the remaining literature and related works. Moreover, one does not clearly see the rationale of this paragraph in the context of "awareness of intention". This reviewer suggests the authors to better introduce their paragraph or to leave a specialist in this field write an article on this other fascinating topics.