Malleability of time through progress bars and throbbers.

Compared to a stationary pattern, a moving pattern dilates the perception of time. However, when it comes to comparing only moving stimulus, the exact dilation effects are less clear. The time dilation may be attributed to either speed of motion, temporal and spatial frequency, stimulus complexity, or the number of changes in the stimulus pattern.

Diffusion modeling of interference and decay in auditory short-term memory.

Decay and interference are two leading proposals for the cause of forgetting from working and/or short-term memory, and mathematical models of both processes exist. In the present study, we apply a computational model to data from a simple short-term memory task and demonstrate that decay and interference can co-occur in the same experimental paradigm, and that neither decay nor interference alone can account for all cases of forgetting.

Overwriting and intrusion in short-term memory.

Studies of interference in working and short-term memory suggest that irrelevant information may overwrite the contents of memory or intrude into memory. While some previous studies have reported greater interference when irrelevant information is similar to the contents of memory than when it is dissimilar, other studies have reported greater interference for dissimilar distractors than for similar distractors. In the present study, we find the latter effect in a paradigm that uses auditory tones as stimuli.

A shared short-term memory system for stimulus duration and stimulus frequency.

Recent research has suggested the existence of a modality-independent memory system that is responsible for storing representations of simple, scalar stimulus attributes, such as the frequency of an auditory pure tone or the duration of a stimulus. In the present study, we modify an existing computational model of short-term memory (STM) for stimulus frequency to allow it to perform STM tasks for both stimulus frequency and stimulus duration, supporting the notion of a common scalar STM system. We further demonstrate the utility of the model by showing that it can reproduce the subjective shortening effect, a classic finding in the psychophysical literature.

TMS-induced neural noise in sensory cortex interferes with short-term memory storage in prefrontal cortex.

In a previous study, Harris et al. (2002) found disruption of vibrotactile short-term memory after applying single-pulse transcranial magnetic stimulation (TMS) to primary somatosensory cortex (SI) early in the maintenance period, and suggested that this demonstrated a role for SI in vibrotactile memory storage. While such a role is compatible with recent suggestions that sensory cortex is the storage substrate for working memory, it stands in contrast to a relatively large body of evidence from human EEG and single-cell recording in primates that instead points to prefrontal cortex as the storage substrate for vibrotactile memory.

Does stimulus complexity determine whether working memory storage relies on prefrontal or sensory cortex?

Traditionally, working and short-term memory (WM/STM) have been believed to rely on storage systems located in prefrontal cortex (PFC). However, recent experimental and theoretical efforts have suggested that, in many cases, sensory or other task-relevant cortex is the actual storage substrate for WM/STM. What factors determine whether a given WM/STM task relies on PFC or sensory cortex? In the present article, we outline recent experimental findings and suggest that the dimensionality or complexity of the to-be-remembered property or properties of a stimulus can be a determining factor.

Irrelevant sensory stimuli interfere with working memory storage: evidence from a computational model of prefrontal neurons.

The encoding of irrelevant stimuli into the memory store has previously been suggested as a mechanism of interference in working memory (e.g., Lange & Oberauer, Memory, 13, 333-339, 2005; Nairne, Memory & Cognition, 18, 251-269, 1990).

Probing the neural basis of perceptual phenomenology with the touch-induced visual illusion.

Using the touch-induced visual illusion we examine whether the brain regions involved in coding sensory information are dissociable from those that contain decision information. Activity in the intraparietal sulcus, as measured by functional magnetic resonance imaging, was associated with the illusion suggesting a sensory coding role whereas activity in the middle occipital gyrus differentially modulated activity according to the decisions made by subjects consistent with their reported perceptual phenomenology.

Can vibrotactile working memory store multiple items?

Vibrotactile working memory is increasing in popularity as a model system to test theories of working memory. Notably, however, we know little about vibrotactile working memory capacity. While most other domains of working memory are able to store multiple items (for example, the seven-plus-or-minus-two capacity of verbal memory [17]), previous examinations of vibrotactile working memory suggest that stored items may suffer from high levels of interference in the form of overwriting or representation-based interference [2,4], potentially limiting capacity and also limiting our ability to draw comparisons between vibrotactile working memory and other forms of working memory.

Diffusion modeling of interference in vibrotactile working memory.

The nature of interference in working memory has been a subject of discussion for decades. It has previously been argued that irrelevant stimuli can interfere with working memory by being encoded into memory. Previous findings have suggested that irrelevant sensory activity can interfere with the storage of information in tactile working memory.

The postcentral gyrus shows sustained fMRI activation during the tactile motion aftereffect.

The tactile motion aftereffect (tMAE) is a perceptual illusion in which a stationary stimulus feels as though it is moving when presented following adaptation to a unidirectionally moving tactile stimulus. Using functional magnetic resonance imaging (fMRI), we localized the brain areas responsive to tactile motion and then investigated whether these areas underlie the tMAE. Tactile stimulation was delivered to the glabrous surface of the right hand by means of a plastic cylinder with a square-wave patterned surface.

Mechanisms of interference in vibrotactile working memory.

In previous studies of interference in vibrotactile working memory, subjects were presented with an interfering distractor stimulus during the delay period between the target and probe stimuli in a delayed match-to-sample task. The accuracy of same/different decisions indicated feature overwriting was the mechanism of interference. However, the distractor was presented late in the delay period, and the distractor may have interfered with the decision-making process, rather than the maintenance of stored information.

Distractor frequency influences performance in vibrotactile working memory.

We use a vibrotactile-delayed match-to-sample paradigm to evaluate the effects of interference on working memory. One of the suggested mechanisms through which interference affects performance in working memory is feature overwriting: Short-term representations are maintained in a finite set of feature units (such as prefrontal neurons), and distractor stimuli co-opt some or all of those units, degrading the stored representation of an earlier stimulus. Subjects were presented with two vibrotactile stimuli and were instructed to determine whether they were of the same or different frequencies.

The effect of adapting speed, duration, and distance on the tactile motion aftereffect.

We investigated the effect of adapting speed, duration, and distance on the frequency of occurrence, duration, and vividness of the tactile motion aftereffect (tMAE). Using a cylindrical drum with a patterned surface we adapted the glabrous surface of the right hand at two speeds (14 and 28 cm/s) and three durations (60, 120, and 240 s). Distance was explored in the interaction of adapting speed and duration.

Site of stimulation effects on the prevalence of the tactile motion aftereffect.

The motion aftereffect (MAE) refers to the apparent motion of a stationary stimulus following adaptation to a continuously moving stimulus. There is a growing consensus that the fast adapting (FA) rather than the slowly adapting (SA) afferent units mediate the tactile version of the MAE. The present study investigated which FA units underlie the tactile MAE by measuring its prevalence, duration, and vividness on different skin areas that vary in their composition of FA units.

Somatosensory temporal discrimination learning generalizes to motor interval production.

The present study investigated whether a common timing mechanism underlies the ability to analyze incoming sensory information and control outgoing motor commands. Participants were presented with two pairs of air puffs on the ventral surface of the right forearm. One pair (the standard interval) was separated by 500 ms on every trial for half of the participants ("500 group") and 800 ms on every trial for the other half ("800 group").

The tactile motion aftereffect revisited.

In two experiments, we measured the direction, duration, frequency, and vividness of the tactile motion aftereffect (MAE) induced by a rotating drum with a ridged surface. In Experiment 1, we adapted the: (1) fingers and palm, including the thumb, (2) fingers and palm, excluding the thumb, and (3) fingers only, excluding the thumb. In each condition the drum rotated at 60 rpm for 120 s.

Symmetric sensorimotor somatotopy.

Background: Functional imaging has recently been used to investigate detailed somatosensory organization in human cortex. Such studies frequently assume that human cortical areas are only identifiable insofar as they resemble those measured invasively in monkeys. This is true despite the electrophysiological basis of the latter recordings, which are typically extracellular recordings of action potentials from a restricted sample of cells.

Preservation of Emmert's law in a visual form agnosic.

Size constancy was investigated in DF, a patient with visual form agnosia, using a technique based on Emmert's law of visual after-images. DF was first given a task in which she was asked to indicate the distance of a vertical surface and a task where she had to estimate the width of a series of squares (widths ranging from 5 cm to 35 cm) placed at varying distances and having a constant visual angle. In the distance estimation task, DF greatly overestimated the distance of the vertical surface placed in front of her.

The influence of familiarity on brain activation during haptic exploration of 3-D facemasks.

Little is known about the neural substrates that underlie difficult haptic discrimination of 3-D within-class object stimuli. Recent work [A.R.

Haptic face identification activates ventral occipital and temporal areas: an fMRI study.

Many studies in visual face recognition have supported a special role for the right fusiform gyrus. Despite the fact that faces can also be recognized haptically, little is known about the neural correlates of haptic face recognition. In the current fMRI study, neurologically intact participants were intensively trained to identify specific facemasks (molded from live faces) and specific control objects.

Recognizing partially visible objects.

In two experiments we measured object recognition performance as a function of delay. In Experiment 1 we presented half of an image of an object, and then the other half after a variable delay. Objects were subdivided into top versus bottom halves, left versus right halves, or vertical strips.

Distributed digit somatotopy in primary somatosensory cortex.

We obtained high-resolution somatotopic maps of the human digits using 4.0 T functional magnetic resonance imaging (fMRI). In separate experiments, the volar surface of either the right thumb, index, or ring finger was stimulated in a sliding-window fashion in both distal-to-proximal and proximal-to-distal directions using a custom-built pneumatic apparatus.

When two eyes are better than one in prehension: monocular viewing and end-point variance.

Previous research has suggested that binocular vision plays an important role in prehension. It has been shown that removing binocular vision affects (negatively) both the planning and on-line control of prehension. It has been suggested that the adverse impact of removing binocular vision is because monocular viewing results in an underestimation of target distance in visuomotor tasks.