Differential Impact of Interference on Internally- and Externally-Directed Attention.

Attention can be oriented externally to the environment or internally to the mind, and can be derailed by interference from irrelevant information originating from either external or internal sources. However, few studies have explored the nature and underlying mechanisms of the interaction between different attentional orientations and different sources of interference. We investigated how externally- and internally-directed attention was impacted by external distraction, how this modulated internal distraction, and whether these interactions were affected by healthy aging. Healthy younger and older adults performed both an externally-oriented visual detection task and an internally-oriented mental rotation task, performed with and without auditory sound delivered through headphones. We found that the addition of auditory sound induced a significant decrease in task performance in both younger and older adults on the visual discrimination task, and this was accompanied by a shift in the type of distractions reported (from internal to external). On the internally-oriented task, auditory sound only affected performance in older adults. These results suggest that the impact of external distractions differentially impacts performance on tasks with internal, as opposed to external, attentional orientations. Further, internal distractibility is affected by the presence of external sound and increased suppression of internal distraction

Reconciling the influence of task-set switching and motor inhibition processes on stop signal after-effects.

Executive response functions can be affected by preceding events, even if they are no longer associated with the current task at hand. For example, studies utilizing the stop signal task have reported slower response times to "GO" stimuli when the preceding trial involved the presentation of a "STOP" signal. However, the neural mechanisms that underlie this behavioral after-effect are unclear. To address this, behavioral and electroencephalography (EEG) measures were examined in 18 young adults (18-30 years) on "GO" trials following a previously "Successful Inhibition" trial (pSI), a previously "Failed Inhibition" trial (pFI), and a previous "GO" trial (pGO). Like previous research, slower response times were observed during both pSI and pFI trials (i.e., "GO" trials that were preceded by a successful and unsuccessful inhibition trial, respectively) compared to pGO trials (i.e., "GO" trials that were preceded by another "GO" trial). Interestingly, response time slowing was greater during pSI trials compared to pFI trials, suggesting executive control is influenced by both task set switching and persisting motor inhibition processes. Follow-up behavioral analyses indicated that these effects resulted from between-trial control adjustments rather than repetition priming effects. Analyses of inter-electrode coherence (IEC) and inter-trial coherence (ITC) indicated that both pSI and pFI trials showed greater phase synchrony during the inter-trial interval compared to pGO trials. Unlike the IEC findings, differential ITC was present within the beta and alpha frequency bands in line with the observed behavior (pSI > pFI > pGO), suggestive of more consistent phase synchrony involving motor inhibition processes during the ITI at a regional level. These findings suggest that between-trial control adjustments involved with task-set switching and motor inhibition processes influence subsequent performance, providing new insights into the dynamic nature of executive control

Enhanced attention using head-mounted virtual reality

Some evidence suggests that experiencing a given scenario using virtual reality (VR) may engage greater attentional resources than experiencing the same scenario on a 2D computer monitor. However, the underlying neural processes associated with these VR-related effects, especially those pertaining to current consumer-friendly head-mounted displays of virtual reality (HMD-VR), remain unclear. Here, two experiments were conducted to compare task performance and EEG-based neural metrics captured during a perceptual discrimination task presented on two different viewing platforms. Forty participants (20–25 years old) completed this task using both an HMD-VR and traditional computer monitor in a within-group, randomized design. Although Experiment I (n = 20) was solely behavioral in design, Experiment II (n = 20) utilized combined EEG recordings to interrogate the neural correlates underlying potential performance differences across platforms. These experiments revealed that (1) there was no significant difference in the amount of arousal measured between platforms and (2) selective attention abilities in HMD-VR environment were enhanced from both a behavioral and neural perspective. These findings suggest that the allocation of attentional resources in HMD-VR may be superior to approaches more typically used to assess these abilities (e.g., desktop/laptop/tablet computers with 2D screens)

Active versus passive maintenance of visual nonverbal memory

Forgetting over the short-term has challenged researchers for more than a century, largely because of difficulty in controlling what goes on within the memory retention interval. But the “recent negative probes” procedure offers a valuable paradigm, by examining influences of (presumably) unattended memoranda from prior trials. Here we used a recent probes task to investigate forgetting for visual non-verbal short-term memory. Target stimuli (2 visually presented abstract shapes) on a trial were followed after a retention interval by a probe, and participants indicated whether the probe matched one of the target items. Proactive interference, and hence memory for old trial probes, was observed whereby participants were slowed in rejecting a non-matching probe on the present trial that nevertheless matched a target item on the previous trial (a recent negative probe). The attraction of the paradigm is that, by uncovering proactive influences of past trial probe stimuli, it is argued that active maintenance in memory of those probes is unlikely. In two experiments we recorded such proactive interference of prior trial items over a range of interstimulus (ISI) and intertrial (ITI) intervals (between 1 and 6 seconds respectively). Consistent with a proposed two-process memory conception (the active-passive memory model or APM), actively maintained memories on current trials decayed but passively “maintained,” or unattended, visual memories of stimuli on past trials did not

Homing in on consciousness in the nervous system: An action-based synthesis

Abstract: The primary function of consciousness in the nervous system remains mysterious. Passive frame theory, a synthesis of empirically supported hypotheses from diverse fields of investigation, reveals that consciousness serves as a frame that constrains and directs skeletal muscle output, thereby yielding adaptive behavior. How consciousness achieves this is more counterintuitive, “low level, ” and passive than the kinds of functions that theorists have attributed to consciousness. From this unique, action-based perspective, consciousness is in the service of the somatic nervous system. The framework begins to isolate the neuroanatomical, cognitive-mechanistic, and representational processes associated with consciousness.