Learning sequence of views of three-dimensional objects: the effect of temporal coherence on object memory

How humans recognize objects remains a contentious issue in current research on high-level vision. Here, I test the proposal by Wallis and Bülthoff (1999 Trends in Cognitive Sciences 3 22-31) suggesting that object representations can be learned through temporal association of multiple views of the same object. Participants first studied image sequences of novel, three-dimensional objects in a study block. On each trial, the images were from either an orderly sequence of depth-rotated views of the same object (SS), a scrambled sequence of those views (SR), or a sequence of different objects (RR). Recognition memory was assessed in a following test block. A within-object advantage was consistently observed --greater accuracy in the SR than the RR condition in all four experiments, greater accuracy in the SS than the RR condition in two experiments. Furthermore, spatiotemporal coherence did not produce better recognition than temporal coherence alone (similar or less accuracy in the SS compared to the SR condition). These results suggest that the visual system can use temporal regularity to build invariant object representations, via the temporal-association mechanism.     

Involuntary attention in the absence of visual awareness

ABSTRACT

Previous studies have found a dissociation between voluntary attention and awareness. Here, we examined the relationship between involuntary attention and awareness. We presented a masked cue such that participants were unaware of the cue. This was followed by a search array, for which participants detected the presence of a shape target. Even though the cue was task irrelevant and unconscious, we observed faster reaction times when either the cue’s location or colour was congruent with shape target. We conclude an unconscious stimulus can elicit both space- and feature-based attention. These results provide further evidence for the dissociation between attention and consciousness.     

Parallel consolidation of simple features into visual short-term memory

Although considerable research has examined the storage limits of visual short-term memory (VSTM), little is known about the initial formation (i.e., the consolidation) of VSTM representations. A few previous studies have estimated the capacity of consolidation to be one item at a time. Here we used a sequential-simultaneous manipulation to reexamine the limits of consolidating items into VSTM. Participants viewed briefly presented and masked color patches (targets), which were shown either sequentially or simultaneously. A probe color followed the targets and participants decided whether it matched one of the targets or was a novel color. In four experiments, we consistently found equal performance for sequential and simultaneous presentations for two targets. Worse performance in the simultaneous than the sequential condition was observed for larger set sizes (three and four). Contrary to previous results, suggesting a severe capacity limit of one item, our results indicate that consolidation into VSTM can occur in parallel and without capacity limits for at least two items.     

Voluntary Attention Enhances Contrast Appearance

ABSTRACT— Voluntary (endogenous, sustained) covert spatial attention selects relevant sensory information for prioritized processing. The behavioral and neural consequences of such selection have been extensively documented, but its phenomenology has received little empirical investigation. We asked whether voluntary attention affects the subjective appearance of contrast—a fundamental dimension of visual perception. We used a demanding rapid serial visual presentation (RSVP) task to direct endogenous attention to a given location and measured perceived contrast at the attended and unattended locations. Attention increased perceived contrast of suprathreshold stimuli and also improved performance on a concurrent orientation discrimination task at the cued location. We ruled out response bias as an alternative account of the pattern of results. Thus, this study establishes that voluntary attention enhances perceived contrast. This phenomenological consequence links behavioral and neurophysiological studies on the effects of attention.