A perceptual phenomenon and its neurophysiological correlate.

A square-wave grating from which the fundamental harmonic has been subtracted (missing fundamental grating) when viewed from a suitable distance appears similar to another grating of periodicity three times higher. The neurons of the visual cortex of the cat, in a given range of spatial frequencies characteristic of each cell, give similar responses to the two gratings.     

Libertarianism,the Rollback Argument,and the Objective Probability of Free Choices

It is widely assumed that candidates for free, undetermined choices must have objective probabilities prior to their performance. Indeed although this premise figures prominently in a widely discussed argument against libertarianism, few libertarians have called it into question. In this article, I will investigate whether libertarians ought to reject it. I will conclude that doing so should not be tempting to event‐causal libertarians or most agent‐causal ones, because the added costs outweigh the benefits.