How does the brain order successive events? Here we studied whether temporal order of two stimuli delivered in rapid succession, one to each hand, is determined before or after the stimuli are localized in space. When their arms were crossed, subjects could accurately report the temporal order, even when the interval between stimuli was as short as 70 ms. In most trials, subjects could also judge temporal order when their arms were crossed, but only if given adequate time (>1 s). At moderately short intervals (<300 ms), crossing the arms caused misreporting (that is, inverting) of the temporal order. Thus, at these intervals, the determining factor of temporal order was the spatial location of the hands. We suggest that it is not until the spatial locations of the hands are taken into account that the cutaneous signals from the respective hands are ordered in time.

Our gaze tends to be directed to objects previously associated with rewards. Such object values change flexibly or remain stable. Here we present evidence that the monkey substantia nigra pars reticulata (SNr) in the basal ganglia represents stable, rather than flexible, object values. After across-day learning of object–reward association, SNr neurons gradually showed a response bias to surprisingly many visual objects: inhibition to high-valued objects and excitation to low-valued objects. Many of these neurons were shown to project to the ipsilateral superior colliculus. This neuronal bias remained intact even after >100 d without further learning. In parallel with the neuronal bias, the monkeys tended to look at high-valued objects. The neuronal and behavioral biases were present even if no value was associated during testing. These results suggest that SNr neurons bias the gaze toward objects that were consistently associated with high values in one’s history.