Review History

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  • The initial submission of this article was received on November 22nd, 2013 and was peer-reviewed by 2 reviewers and the Academic Editor.
  • The Academic Editor made their initial decision on December 23rd, 2013.
  • The first revision was submitted on February 18th, 2014 and was reviewed by 1 reviewer and the Academic Editor.
  • A further revision was submitted on March 24th, 2014 and was reviewed by the Academic Editor.
  • The article was Accepted by the Academic Editor on March 24th, 2014.

Version 0.3 (accepted)

· · Academic Editor


The raised issues have been addressed in a satisfactory way.

Version 0.2

· · Academic Editor

Major Revisions

After reading the manuscript and the reviewers comments, my decision is to give you the possibility to address the raised issues.

Reviewer 2 ·

Basic reporting

The Figures are appropriate and improved from the first version of the manuscripts.

Experimental design

As requested, the authors provided a more detailed and satisfying description of the experimental protocol.

Validity of the findings

A description of the statistical evaluation of the data is still missing as also a between subject analysis among the groups. Since one of their conclusion concerns the comparison between groups (as stated by the authors in line 261), I think this lack remains a strong limit of the work. Why do they not directly inputs the data of paradigm 2 and 3 within the same statistical analysis?

Version 0.1 (original submission)

· · Academic Editor

Major Revisions

Both external reviewers appreciated your work but raise some points that should be clarified. I consider of particular relevance their doubts on the analysis.

Reviewer 1 ·

Basic reporting

No Comments

Experimental design

The experiment is well designed. The presentation of the results is clear. Somme information about the instructions given to the subjects relative to movement speed is lacking. The authors should report the results of the statistical analysis into the text.
Why Figure 9 is at the end of the paper? Alson into the text it appears after figure 2. Please change.

Validity of the findings

-I think that movement amplitude (5cm) was too short to speak about 'movement'.
-Authors argue about movement direction as a major parameter of movement planning. In generally, this is true. However, in their experiment they manipulated only movement direction, movement amplitude was only 5cm, and they measured only direction errors. Thus, they must formulate more moderate conclusions.
-They argued in favor of the 'vectorial planning hypothesis' because the significance lever, although present, was weaker in P3. Do they think that this is a sufficient argument?
The last conclusion (lines 366-369) is not original.

Reviewer 2 ·

Basic reporting


In all the figures I suggest to put a legend of the colors. This would simplify and speed up the comprehension of the figure.

In Figure 7 and 9 it would be useful to indicate at the right side and at the top, respectively, the experimental condition (e.g., Figure 9, on the top of the left side ”forward” and right side “backward”).

In the figure legend the rankum test is mentioned. However, no description in the text of this analysis appears. Please provide descrption of the statistical analysis in the text.

Experimental design

Paradigm and Trial-Sequence. The authors should provide a more detailed description of the protocol.

The number of trials of the three protocols are the same. However, whether in P1 there are 12 target positions, in P2 and P3 only 2 endpoints appeared. This can affect the results in term of learning and transfer. Furthermore, the attentional load in the P1 with respect to P2 and P3 could be different. Please provide a comment.

Do target positions in P2 and P3 correspond to some of the target positions in P1? If so, it is not clear the need to perform P2 and P3.

The number of trials per each block and each target direction is not clearly described.

When looking at Table 1 and also to the figures it appears that protocols P2 and P3 are divided in P2a, P2b, P3a, P3b but they are not mentioned in the paradigm description.

Validity of the findings

Data Analysis

Lines 139-140. Why do the authors choose “the point in time 100 ms before the 45 percent of maximal hand-velocity” as movement onset? This sounds a little bit strange. Please motivate this choice or provide proper quotations.

Lines 155-159. Movement errors were fitted with linear and exponential functions, depending on the blocks. A statistical comparison among the parameters of the fits could be useful to compare the trend of initial movement error in the different protocols and directions.

Lines 160-168. The three protocols are balanced for total number of trials but not for movement direction. This implies that the number of repetitions per direction are very different and could have affected the statistical evaluation.

In the statistical analysis why the authors did not take into account the potential differences among the 12 movement directions?

Why in P1 “50 trials in the beginning and in the end of the block” were pooled together whether in P2 and P3 the trials were sorted by targets and only 15 movement were considered for the analysis?

The description of the tests used to provide the statistical results is missing.

Backward movements

The effects of the different protocols on movement performance are only discussed basing on the differences in the level of significance of the p value. In fact, the statistical evaluation is limited to comparison with-in the same group. A between subject analysis among the three groups of subjects is missing. Following the presented results it is difficult to conclude that the transfer of meaning occurred in a direction specific way. This is a strong limit of the work.

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