Disappearing Percepts: Evidence for Retention Failure in Metacontrast Masking

Does sensitivity in binary choice tasks depend on response modality?

In most models of vision, a stimulus is processed in a series of dedicated visual areas, leading to categorization of this stimulus, and possible decision, which subsequently may be mapped onto a motor-response. In these models, stimulus processing is thought to be independent of the response modality. However, in theories of event coding, common coding, and sensorimotor contingency, stimuli may be very specifically mapped onto certain motor-responses. Here, we compared performance in a shape localization task and used three different response modalities: manual, saccadic, and verbal. Meta-contrast masking was employed at various inter-stimulus intervals (ISI) to manipulate target visibility. Although we found major differences in reaction times for the three response modalities, accuracy remained at the same level for each response modality (and all ISIs). Our results support the view that stimulus-response (S-R) associations exist only for specific instances, such as reflexes or skills, but not for arbitrary S-R pairings.

Visual masking and the dynamics of human perception, cognition, and consciousness A century of progress, a contemporary synthesis, and future directions

The 1990s, the “decade of the brain,” witnessed major advances in the study of visual perception, cognition, and consciousness. Impressive techniques in neurophysiology, neuroanatomy, neuropsychology, electrophysiology, psychophysics and brain-imaging were developed to address how the nervous system transforms and represents visual inputs. Many of these advances have dealt with the steady-state properties of processing. To complement this “steady-state approach,” more recent research emphasized the importance of dynamic aspects of visual processing. Visual masking has been a paradigm of choice for more than a century when it comes to the study of dynamic vision. A recent workshop (http://lpsy.epfl.ch/VMworkshop/), held in Delmenhorst, Germany, brought together an international group of researchers to present state-of-the-art research on dynamic visual processing with a focus on visual masking. This special issue presents peer-reviewed contributions by the workshop participants and provides a contemporary synthesis of how visual masking can inform the dynamics of human perception, cognition, and consciousness.

Inhibition of return: Sensitivity and criterion as a function of response time

Inhibition of return (IOR) refers to a mechanism that results in a performance disadvantage typically observed when targets are presented at a location once occupied by a cue. Although the time course of the phenomenon--from the cue to the target--has been well studied, the time course of the effect--from target to response--is unknown. In 2 experiments, the effect of IOR upon sensitivity and response criterion under different levels of speed stress was examined. In go/no-go and choice reaction time tasks, IOR had at least 2 distinct effects on information processing. Early in target processing, before sufficient target information has accrued, there is a bias against responding to cued targets. Later, as target information is allowed to accrue, IOR reduces sensitivity to the target's nonspatial feature. Three accounts relating to the early bias effect of IOR and the late effect of IOR on sensitivity are offered.

An ostrich on a rock: commentary on Christie and Barresi (2002)

There are problems with both the theoretical logic and the interpretation of data in Christie and Barresi's (2002) interesting article. The general pattern of results (described as Orwellian) is easily incorporated into an information-processing framework compatible with Dennett's analysis. In particular, different aspects of the illusory motion event are queried at different times and these aspects (line extent and manner of appearance) are not in conflict, so no revision of conscious content is necessary. Second, too much interpretive weight is placed on an anomalous pair of data points (described as Stalinesque) that do not seem fully interpretable within the author's framework and are probably susceptible to one of several alternative interpretations proposed here, though further investigation is necessary.