Many tuning curves are not “well-behaved”.

<p>A: typical example of tuning curve from the spatially-separated afix condition (compare with <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0146500#pone.0146500.g001" target="_blank">Fig 1F</a>). The shape of the curve—including the position of the two peaks that should be elicited by the composite RDP stimulus—cannot reliably be inferred due to large error bars (std.). B: Histogram of estimated firing rate standard deviations (expressed in relative units, as ratios between std. and a matching mean), obtained by lumping together all stimulus directions and attentional conditions, for the spatially separated (left) and the transparent (right) paradigms. Both these histograms are strongly right-skewed, denoting the existence of cells with highly variable responses to certain stimuli.</p>