Repetition learning in the immediate serial recall of visual and auditory materials.

In 5 experiments, a Hebb repetition effect, that is, improved immediate serial recall of an (unannounced) repeating list, was demonstrated in the immediate serial recall of visual materials, even when use of phonological short-term memory was blocked by concurrent articulation. The learning of a repeatedly presented letter list in one modality (auditory or visual) did not transfer to give improved performance on the same list in the other modality. This result was not replicated for word lists, however, for which asymmetric transfer was observed.

Automated post-hoc noise cancellation tool for audio recordings acquired in an MRI scanner.

There are several types of experiment in which it is useful to have subjects speak overtly in a magnetic resonance imaging (MRI) scanner, including those studying the articulatory apparatus and the neural basis of speech production, and fMRI experiments in which speech is used as a response modality. Although it is relatively easy to record sound from the bore, it can be difficult to hear the speech over the very loud acoustic noise from the scanner. This is particularly a problem during echo-planar imaging, which is usually used for fMRI.

Prefrontal cortical involvement in verbal encoding strategies.

The lateral prefrontal cortex is critical for the control and organization of information in working memory. In certain situations, effective reorganization can attenuate task difficulty, suggesting a dissociation between lateral prefrontal activity and basic memory demand. In a verbal working memory task, we investigated the enhancement of performance that occurs when incoming information can be reorganized into higher-level groups or chunks.

Testing a positional model of the Hebb effect.

In two experiments, we investigated the hypothesis that a strengthening of position-item associations underlies the improvement seen in performance on an immediate serial recall task, for a list that is surreptitiously repeated every third trial. Having established a strong effect of repetition, performance was tested on transfer lists in which half the items held the same position as in the repeated list (S-items) and the remainder moved (D-items). In Experiment 1, S-items showed a small advantage in order errors over control and D-items.