Perception of timing is more context sensitive than sensorimotor synchronization

In three experiments, the effects of contextual temporal variation on the perception of timing and on sensorimotor synchronization were examined. Experiment 1 showed that exposure to a variably timed auditory precursor sequence reduces the detectability of deviations from isochrony in a musical test sequence. By contrast, in Experiment 2 there was only a small and transient effect of identical precursor sequences on the variability of finger taps that were synchronized with a similar test sequence. Moreover, the precursor did not impede phase error correction following deviations from isochrony in the test sequence. Experiment 3 employed a within-subjects design that required simultaneous detection of irregularities in and synchronization with nonmusical auditory sequences. Precursor variability impaired only detection, not synchronization performance. These results suggest that perception of deviations from regularity engages context-sensitive tining processes, probably related to conscious awareness, that are not involved in sensorimotor synchronization.     

Dissociating perception and action in Kanizsa's compression illusion

When a horizontally elongated surface is occluded in the middle by a larger surface, it appears narrower than its true width (Kanizsa’s compression illusion). We report that a similar compression effect occurs for closed-loop visuomotor matches of size, but not for otherwise comparable open-loop “mimed” reaching or size-matching visuomotor responses. Our study is the first in which a comparison of size perception in personal space with bilateral actions performed with both hands (instead of precision grips employing the thumb and the index finger) is used to investigate motor responses to Kanizsa’s compression illusion. Implications for the current debate on the existence of dissociations between spatial perception and visually controlled actions in personal space are discussed.     

Unifying sequential effects in perceptual grouping

Temporally-extended perception involves a delicate balance of constancy and change. 'This can be seen, for instance, when viewing bistable figures such as the Necker cube. A recent study by Gepshtein and Kubovy of sequential effects in multistable dot lattices demonstrates constancy and change within the same set of data. They propose that these opposing trends might be explained by the same single factor: a persistent random orientation bias that is intrinsic to brain activity. This proposal could form the basis for a new account of multistability.     

Observation and judgment in psychology: Assessing agreement among markings of behavioral events

In a sequence from a videotaped dialogue between two persons (e.g., psychotherapist and patient), observers are given the task of searching for, marking, and commenting on conspicuous events. The observers receive no information on where to look for conspicuous events and no information on what events are worth marking. Moreover, nothing is known about the observers’ marking preferences. Marking is therefore very spontaneous and subjective. This marking freedom leads to the problem that a superimposition of all observers’ markings yields complicated configurations of mutually overlapping intervals. To address this difficulty, a new definition of the concept of marking agreement is proposed that is based upon relational considerations. According to this definition, a set ofagreeing marking subsets of various sizes can be found in marking configurations. A significance concept is proposed to allow comparison of different configurations, and standardization on the basis of random configurations is performed using Monte Carlo simulations.     

Face inversion disproportionately impairs the perception of vertical but not horizontal relations between features

Upside-down inversion disrupts the processing of spatial relations between the features of a face, while largely preserving local feature analysis. However, recent studies on face inversion failed to observe a clear dissociation between relational and featural processing. To resolve these discrepancies and clarify how inversion affects face perception, the authors monitored inversion effects separately for vertical and horizontal distances between features. Inversion dramatically declined performance in the vertical-relational condition, but it impaired featural and horizontal-relational performance only moderately. Identical observations were made whether upright and inverted trials were blocked or randomly interleaved. The largest performance decrement was found for vertical relations even when faces were rotated by 90 degrees. Evidence that inversion dramatically disrupts the ability to extract vertical but not horizontal feature relations supports the view that inversion qualitatively changes face perception by rendering some of the processes activated by upright faces largely ineffective.     

Autobiographical recall training in elderly adults with subjective memory complaint: a pilot study

Subjective memory complaint is a self-reported memory impairment which affects elderly people. This problem does not interfere with daily living activities but could decrease quality of life. This study's purpose was to verify whether a specific, newly developed, autobiographical recall training could modify self-perception of memory of subjects with subjective memory complaint. Seven elderly subjects (4 women and 3 men; mean age 65.5 yr., SD=11) with such complaint, evidenced through a specific questionnaire, attended the training course and were prospectively assessed on standard neuropsychological tests, depressive symptomatology, and self-perception of memory. Self-perception of memory, as assessed by scores on a formalized questionnaire, improved significantly after the training, while depressive symptoms did not change. Neuropsychological performances were normal before and after the training, but a statistically significant improvement was observed only on the phonological fluency test. Thus the present pilot study suggested that the training may be effective in improving self-perception of memory and metamnestic capacity in elderly people with subjective memory complaints but not in changing subjects' depressive symptoms. This requires replication of this work with a much larger sample so statistical power is adequate.     

Perceiving the numerosity of rapidly occurring auditory events in metrical and nonmetrical contexts

Experiment 1 determined the fastest tempo at which participants could tap in synchrony with every nth tone (n = 2 to 9) in an isochronous sequence. Tapping was difficult with every 5th or 7th tone but easy with every 2nd, 4th, or 8th tone, suggesting that evenly divisible groups of n tones are automatically subdivided into equal groups of 2 or 3-a form of auditory subitizing that generates metrical hierarchies commonly found in Western music. Experiments 2 and 3 sought evidence of subitizing and subdivision in timed explicit enumeration of short, rapidly presented tone sequences (n = 2 to 10). Enumeration accuracy decreased monotonically with n. Response time increased monotonically up to n = 5 or 6, but less between 2 and 3 than between 3 and 4. Thus, a single group of 2 or 3 tones perhaps can be subitized, but subdivision of larger groups into subgroups of 2 or 3 tones seems to be specific to a repetitive, metrical context.     

Unconscious, stimulus-dependent priming and conscious, percept-dependent priming with chromatic stimuli

Using metacontrast masking to suppress the conscious registration of a prime stimulus, Breitmeyer, Ro, and Singhal (2004) showed that color priming produced by a masked prime disk occurs at unconscious stimulus-dependent rather than at percept-dependent levels of visual processing. The current set of experiments compares this type of unconscious stimulus-dependent priming to conscious priming produced by a prime that, in two separate ways, is rendered visible and thus activates percept-dependent visual processes. The results indicate that while the masked prime again acts at a stimulus-dependent level of processing, the unmasked, visible primes additionally act at a later percept-dependent level of processing.     

Pianists duet better when they play with themselves: on the possible role of action simulation in synchronization

Ensemble musicians play in synchrony despite expressively motivated irregularities in timing. We hypothesized that synchrony is achieved by each performer internally simulating the concurrent actions of other ensemble members, relying initially on how they would perform in their stead. Hence, musicians should be better at synchronizing with recordings of their own earlier performances than with others' recordings. We required pianists to record one part from each of several piano duets, and later to play the complementary part in synchrony with their own or others' recordings. The pianists were also asked to identify their own recordings. The pianists were better at synchronizing with their own than with others' performances, and they were able to recognize their own recordings. Furthermore, synchronization accuracy and recognition were correlated: Pianists who were relatively accurate at synchronizing with their own performances were also good at recognizing them. Thus, action simulation may underlie both synchronization and self-recognition.