In Figure 7(A) the lines are seen as a wire frame, whereas Figure 7(B) appears as an opaque cube, i.e. in this case the lines do "appear to pull the white surface of the page into depth". Admittedly Figure 7 (C) is ambiguous in this regard as it can be seen either way (although I tend to see it as a surface percept). I have avoided extensive discussion of the perception of transparency, since the emergence of a depth percept from the configuration of three-dimensional edges would occur essentially in the same manner, as suggested with the rod-and-rail model. Besides, the full surface percept is actually more challenging to model, since it requires more surface reification, which is a primary focus of this paper. In the new draft I have reworded the description of the three-arm vertex percept to say "If this is seen as a three-dimensional solid, the lines in the figure appear to pull the white surface of the page into depth between the lines...". Again, if the reviewer denies this perceptual possibility in Figure 7 (C), as long as he can imagine a case where such a perceptual interaction is observed, for example Figure 7 (B), then that is sufficient to reveal the existence of this perceptual tendency. Again, the figures presented in this paper are not the primary evidence of the phenomena described, but are merely included for illustrative purposes.

Figure 7.