A more recent view holds that tangible qualities are best understood as intensive features that vary in intensity along a single dimension of variation (Fulkerson 2014b). When we feel vibration, for instance, it seems to increase in intensity (in this case, in frequency) along a single qualitative dimension. This seems to be true of most tangible features. They are not typically complex, but simples that vary along a single dimension. This view accords well with the empirical data and offers a unified explanation for the structural connections between an otherwise disjoint collection of sensory features. One worry for this view, however, again concerns our awareness of hot and cold. Variations in intensity alone do not seem apt for capturing the nature of hot and cold experiences (see below). Rather than varying along a single dimension, our experiences of hot and cold seem to vary in intensity in two directions around a neutral point (Gray 2012). Cold experiences are those that vary away from neutral in one direction; our experiences of warmth vary away from neutral in the other (increasing) direction. More importantly, it seems the nature of these movements depends more on changes in our current bodily state than the objective measures of temperature. So once again, thermal properties seem to pose additional difficulties not faced by other tangible qualities.