Working Memory in Unilateral Spatial Neglect: Evidence for Impaired Binding of Object Identity and Object Location.

Working memory (WM) is known to be impaired in patients with stroke experiencing unilateral spatial neglect (USN). Here, we examined in a systematic manner three WM components: memory of object identity, memory of object location, and binding between object identity and location. Moreover, we used two different retention intervals to isolate maintenance from other mnemonic and perceptual processes. Fourteen USN first-event stroke patients with right-hemisphere damage were tested in two different WM experiments using long and short retention intervals and an analog response scale. Patients exhibited more identification errors for items displayed on the contralesional side. Localization errors were also more prominent in the contralesional side, especially after a long retention interval. These localization errors were often a result of swap errors, that is, erroneous localizations of correctly identified contralesional objects in correctly memorized locations of ipsilesional objects. We conclude that a key WM deficit in USN is a lateralized impairment in binding between the identity of an object and its spatial tag.

Adaptive visual working memory: Expecting a delayed estimation task enhances visual working memory precision.

Two of the dominating tasks in the visual working memory (VWM) literature are the Delayed Estimation (DE) task and the Change Detection (CD) task. However, there are no studies that directly compared how participants' expectation to be tested in these tasks impacts memory formation. Here, three experiments interspersed DE and CD trials with identical displays until the reporting stage. During each session, the frequency of trials of each task was altered to manipulate expectations of which task would be required. Expectation of a DE task led to an increase in the number of fixations during encoding and to more precise estimation. By contrast, expectation of a CD trial did not modulate CD accuracy. These results suggest that the precision with which information is encoded into VWM differs between these two tasks. This has implications for current theoretical debates on VWM and underscores the importance of the typically overlooked effect of task type on memory performance. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Verbal tagging can impair memory of object location: Evidence from aphasia.

The impact of damage to different regions and functional systems of the brain on visual working memory is far from understood. Here we examined how impaired object naming due to brain damage affects object identity and location information in working memory. Ten first-event stroke patients with aphasia performed a "delayed estimation" task that examines memory of object location separately from memory of object identity, using a continuous reporting scale. Following a delay of 4 s, objects that could not be named by the aphasic patients were localized more precisely than objects that could be named. The results are interpreted with reference to classic models separating phonological from visuospatial working memory, and with reference to the "verbal overshadowing" effect that is typically associated with long-term memory.

Oculomotor anticipation reveals a multitude of learning processes underlying the serial reaction time task.

Sequence learning is the cognitive faculty enabling everyday skill acquisition. In the lab, it is typically measured in speed of response to sequential stimuli, whereby faster responses are taken to indicate improved anticipation. However, response speed is an indirect measure of anticipation, that can provide only limited information on underlying processes. As a result, little is known about what is learned during sequence learning, and how that unfolds over time. In this work, eye movements that occurred before targets appeared on screen in an ocular serial reaction time (O-SRT) task provided an online indication of where participants anticipated upcoming targets. When analyzed in the context of the stimuli preceding them, oculomotor anticipations revealed several simultaneous learning processes. These processes influenced each other, as learning the task grammar facilitated acquisition of the target sequence. However, they were dissociable, as the grammar was similarly learned whether a repeating sequence inhabited the task or not. Individual differences were found in how the different learning processes progressed, allowing for similar performance to be produced for different latent reasons. This study provides new insights into the processes subserving sequence learning, and a new method for high-resolution study of it.

Are stronger memories forgotten more slowly? No evidence that memory strength influences the rate of forgetting.

Information stored in visual short-term memory is used ubiquitously in daily life; however, it is forgotten rapidly within seconds. When more items are to be remembered, they are forgotten faster, potentially suggesting that stronger memories are forgotten less rapidly. Here we tested this prediction with three experiments that assessed the influence of memory strength on the rate of forgetting of visual information without manipulating the number of items. Forgetting rate was assessed by comparing the accuracy of reports in a delayed-estimation task following relatively short and long retention intervals. In the first experiment, we compared the forgetting rate of items that were directly fixated, to items that were not. In Experiments 2 and 3 we manipulated memory strength by extending the exposure time of one item in the memory array. As expected, direct fixation and longer exposure led to better accuracy of reports, reflecting stronger memory. However, in all three experiments, we did not find evidence that increased memory strength moderated the forgetting rate.