We are interested in number as both a perceptual and cognitive dimension. We are interested in questions like:

• Is number (perceptually) special — and how might this bear on the development of conceptual number knowledge, across the lifespan and across generations?

• Are babies born with innate knowledge of number, and how does this relate to other innate knowledge?

• What mechanisms support the perception/representation of number, and to what extent are those mechanisms common across other quantity dimensions like area and density?

• To what extent is our sense of number illusory, and what might that reveal about both number and perception?

• What does the perception of number reveal about perceptual systems in general?

• How do we determine whether properties like number are truly perceptual in the first place?