Task-irrelevant Representations Research Articles

TIB: Detecting Unknown Objects via Two-Stream Information Bottleneck.

Detecting diverse objects, including ones never-seen-before during training, is critical for the safe application of object detectors. To this end, a task of unsupervised out-of-distribution object detection (OOD-OD) is proposed to detect unknown objects without the reliance on an auxiliary dataset. For this task, it is important to reduce the impact of lacking unknown data for supervision and leverage in-distribution (ID) data to improve the model's discrimination. In this paper, we propose a method of Two-Stream Information Bottleneck (TIB), consisting of a standard IB and a dedicated Reverse Information Bottleneck (RIB). Specifically, after extracting the features of an ID image, we first define a standard IB network to disentangle instance representations that are beneficial for localizing and recognizing objects. Meanwhile, we present RIB to obtain simulative OOD features to alleviate the impact of lacking unknown data. Different from standard IB aiming to extract task-relevant compact representations, RIB is to obtain task-irrelevant representations by reversing the optimization objective of the standard IB. Next, to further enhance the discrimination, a mixture of information bottlenecks is designed to sufficiently capture object-related information. Experimental results on OOD-OD, open-vocabulary object detection, incremental object detection, and open-set object detection show the superiorities of our method.

Learning Causal Representations for Robust Domain Adaptation

Domain adaptation solves the learning problem in a target domain by leveraging the knowledge in a relevant source domain. While remarkable advances have been made, almost all existing domain adaptation methods heavily require large amounts of unlabeled target domain data for learning domain invariant representations to achieve good generalizability on the target domain. In fact, in many real-world applications, target domain data may not always be available. In this paper, we study the cases where at the training phase the target domain data is unavailable and only well-labeled source domain data is available, called robust domain adaptation. To tackle this problem, under the assumption that causal relationships between features and the class variable are robust across domains, we propose a novel Causal AutoEncoder (CAE), which integrates deep autoencoder and causal structure learning into a unified model to learn causal representations only using data from a single source domain. Specifically, a deep autoencoder model is adopted to learn low-dimensional representations, and a causal structure learning model is designed to separate the low-dimensional representations into two groups: causal representations and task-irrelevant representations. Using three real-world datasets the extensive experiments have validated the effectiveness of CAE compared to eleven state-of-the-art methods.

A large-scale analysis of task switching practice effects across the lifespan

An important feature of human cognition is the ability to flexibly and efficiently adapt behavior in response to continuously changing contextual demands. We leverage a large-scale dataset from Lumosity, an online cognitive-training platform, to investigate how cognitive processes involved in cued switching between tasks are affected by level of task practice across the adult lifespan. We develop a computational account of task switching that specifies the temporal dynamics of activating task-relevant representations and inhibiting task-irrelevant representations and how they vary with extended task practice across a number of age groups. Practice modulates the level of activation of the task-relevant representation and improves the rate at which this information becomes available, but has little effect on the task-irrelevant representation. While long-term practice improves performance across all age groups, it has a greater effect on older adults. Indeed, extensive task practice can make older individuals functionally similar to less-practiced younger individuals, especially for cognitive measures that focus on the rate at which task-relevant information becomes available.

Attentional guidance from two representations of the same or different dimensions in visual working memory

Previous studies have only focused on the interference effect induced by multiple task-irrelevant representations from the same dimensions in visual working memory (VWM). The present study reexamined the issue by not only focusing on interference effect but also facilitation effect induced by multiple task-irrelevant representations from the same dimension in VWM. Furthermore, the guidance effect of multiple task-irrelevant representations from different dimensions in VWM was also investigated. Participants were instructed to complete a gap-location search task while holding two items in VWM. In Experiment 1, one of the colors (match-1) or both colors in VWM (match-2) matched with one or two targets or distractors in the search array. No guidance effects were found for match-1 trials, but there was a reliable interference effect when both colors in VWM were presented as distractors and a facilitation effect when they matched the color of two search targets. Experiment 2 was carried out to examine the guidance effect produced by multiple task-irrelevant representations from different dimensions in VWM. Participants were required to memorize the color and direction of an arrow. Attentional guidance effects were found when each one of the VWM features matched the search target, but there was no additive facilitation effect when both features were validated in visual search. These results provide evidence that multiple items in VWM can guide the attention simultaneously, but the guidance effects are flexible and various across different types of stimuli.

Arousal amplifies biased competition between high and low priority memories more in women than in men: The role of elevated noradrenergic activity

Recent findings indicate that emotional arousal can enhance memory consolidation of goal-relevant stimuli while impairing it for irrelevant stimuli. According to one recent model, these goal-dependent memory tradeoffs are driven by arousal-induced release of norepinephrine (NE), which amplifies neural gain in target sensory and memory processing brain regions. Past work also shows that ovarian hormones modulate activity in the same regions thought to support NE’s effects on memory, such as the amygdala, suggesting that men and women may be differentially susceptible to arousal’s dual effects on episodic memory. Here, we aimed to determine the neurohormonal mechanisms that mediate arousal-biased competition processes in memory. In a competitive visuo-attention task, participants viewed images of a transparent object overlaid on a background scene and explicitly memorized one of these stimuli while ignoring the other. Participants then heard emotional or neutral audio-clips and provided a subjective arousal rating. Hierarchical generalized linear modeling (HGLM) analyses revealed that greater pre-to-post task increases in salivary alpha-amylase (sAA), a biomarker of noradrenergic activity, was associated with significantly greater arousal-enhanced memory tradeoffs in women than in men. These sex-dependent effects appeared to result from phasic and background noradrenergic activity interacting to suppress task-irrelevant representations in women but enhancing them in men. Additionally, in naturally cycling women, low ovarian hormone levels interacted with increased noradrenergic activity to amplify memory selectivity independently of emotion-induced arousal. Together these findings suggest that increased noradrenergic transmission enhances preferential consolidation of goal-relevant memory traces according to phasic arousal and ovarian hormone levels in women.

Increased experience amplifies the activation of task-irrelevant category representations.

Prior research has demonstrated the benefits (i.e., task-relevant attentional selection) and costs (i.e., task-irrelevant attentional capture) of prior knowledge on search for an individual target or multiple targets from a category. This study investigated whether the level of experience with particular categories predicts the degree of task-relevant and task-irrelevant activation of item and category representations. Adults with varying levels of dieting experience (measured via 3 subscales of Disinhibition, Restraint, Hunger; Stunkard & Messick, Journal of Psychosomatic Research, 29(1), 71-83, 1985) searched for targets defined as either a specific food item (e.g., carrots), or a category (i.e., any healthy or unhealthy food item). Apart from the target-present trials, in the target-absent "foil" trials, when searching for a specific item (e.g., carrots), irrelevant items from the target's category (e.g., squash) were presented. The ERP (N2pc) results revealed that the activation of task-relevant representations (measured via Exemplar and Category N2pc amplitudes) did not differ based on the degree of experience. Critically, however, increased dieting experience, as revealed by lower Disinhibition scores, predicted activation of task-irrelevant representations (i.e., attentional capture of foils from the target item category). Our results suggest that increased experience with particular categories encourages the rapid activation of category representations even when category information is task irrelevant, and that the N2pc in foil trials could potentially serve as an indication of experience level in future studies on categorization.

Selective Attentional Enhancement and Inhibition of Fronto-Posterior Connectivity by the Basal Ganglia During Attention Switching

The prefrontal cortex and the basal ganglia interact to selectively gate a desired action. Recent studies have shown that this selective gating mechanism of the basal ganglia extends to the domain of attention. Here, we investigate the nature of this action-like gating mechanism for attention using a spatial attention-switching paradigm in combination with functional neuroimaging and dynamic causal modeling. We show that the basal ganglia guide attention by focally releasing inhibition of task-relevant representations, while simultaneously inhibiting task-irrelevant representations by selectively modulating prefrontal top-down connections. These results strengthen and specify the role of the basal ganglia in attention. Moreover, our findings have implications for psychological theorizing by suggesting that inhibition of unattended sensory regions is not only a consequence of mutual suppression, but is an active process, subserved by the basal ganglia.

Task-Relevant and Accessory Items in Working Memory Have Opposite Effects on Activity in Extrastriate Cortex

During visual search, the working memory (WM) representation of the search target guides attention to matching items in the visual scene. However, we can hold multiple items in WM. Do all these items guide attention at the same time? Using a new functional magnetic resonance imaging visual search paradigm, we found that items in WM can attain two different states that influence activity in extrastriate visual cortex in opposite directions: whereas the target item in WM enhanced processing of matching visual input, other "accessory" items in memory suppressed activity. These results imply that the representation of task-relevant and (currently) task-irrelevant representations in WM differs, revealing new insights into the organization of human visual WM. The suppressive influence of irrelevant WM items may complement the attention-guiding influence of task-relevant WM items, helping us to focus on task-relevant information without getting distracted by irrelevant memory content.

The impact of familial risk for schizophrenia or bipolar disorder on cognitive control during episodic memory retrieval

Episodic memory impairment is a robust correlate of familial risk for schizophrenia (SZ) and bipolar disorder (BD); still much is unknown about the processes that underlie this deficit and how they may be implicated in BD and SZ. We examined the possibility that (a) episodic memory impairment may arise from abnormalities in the cognitive control of interference between task-relevant and task-irrelevant memories during retrieval; inability to suppress task-irrelevant representations could give rise to intrusions of inappropriate memories and increased rate of forgetting, (b) cognitive control deficits during retrieval may be differentially affected by familial predisposition to SZ or BD. We examined episodic memory in relatives of patients with SZ (SZ-R) (n=15) or BD (BD-R) (n=17) compared to healthy controls (n=23) using the California Verbal Learning Test (CVLT) and the Doors and People Test (DPT). All relatives were free of any psychiatric morbidity and were matched to controls on age, sex, educational achievement and general intellectual ability. During the CVLT, both relatives' groups made significantly more perseverative recall errors than controls. However, intrusion errors were significantly increased in SZ-R only. SZ-R also showed increased rate of forgetting in the DPT while BD-R were comparable to controls. Familial predisposition to SZ, compared to that of BD, was associated with significantly greater impairment in cognitive control processes during episodic memory retrieval with some evidence of specificity for SZ in connection with mechanisms relating to increased forgetting.

How Do Speakers Resist Distraction?

Even in the presence of irrelevant stimuli, word production is a highly accurate and fluent process. But how do speakers prevent themselves from naming the wrong things? One possibility is that an attentional system inhibits task-irrelevant representations. Alternatively, a verbal self-monitoring system might check speech for accuracy and remove errors stemming from irrelevant information. Because self-monitoring is sensitive to social appropriateness, taboo errors should be intercepted more than neutral errors are. To prevent embarrassment, speakers might also speak more slowly when confronted with taboo distractors. Our results from two experiments are consistent with the self-monitoring account: Examining picture-naming speed (Experiment 1) and accuracy (Experiment 2), we found fewer naming errors but longer picture-naming latencies for pictures presented with taboo distractors than for pictures presented with neutral distractors. These results suggest that when intrusions of irrelevant words are highly undesirable, speakers do not simply inhibit these words: Rather, the language-production system adjusts itself to the context and filters out the undesirable words.

Top-down suppression deficit underlies working memory impairment in normal aging

In this study, we assess the impact of normal aging on top-down modulation, a cognitive control mechanism that supports both attention and memory by the suppression and enhancement of sensory processing in accordance with task goals. Using fMRI (functional magnetic resonance imaging), we show that healthy older adults demonstrated a prominent deficit in the suppression of cortical activity associated with task-irrelevant representations, whereas enhancement of task-relevant activity was preserved. Moreover, this suppression-specific attention deficit correlated with impaired working memory performance.

Dopamine-mediated stabilization of delay-period activity in a network model of prefrontal cortex.

The prefrontal cortex (PFC) is critically involved in working memory, which underlies memory-guided, goal-directed behavior. During working-memory tasks, PFC neurons exhibit sustained elevated activity, which may reflect the active holding of goal-related information or the preparation of forthcoming actions. Dopamine via the D1 receptor strongly modulates both this sustained (delay-period) activity and behavioral performance in working-memory tasks. However, the function of dopamine during delay-period activity and the underlying neural mechanisms are only poorly understood. Recently we proposed that dopamine might stabilize active neural representations in PFC circuits during tasks involving working memory and render them robust against interfering stimuli and noise. To further test this idea and to examine the dopamine-modulated ionic currents that could give rise to increased stability of neural representations, we developed a network model of the PFC consisting of multicompartment neurons equipped with Hodgkin-Huxley-like channel kinetics that could reproduce in vitro whole cell and in vivo recordings from PFC neurons. Dopaminergic effects on intrinsic ionic and synaptic conductances were implemented in the model based on in vitro data. Simulated dopamine strongly enhanced high, delay-type activity but not low, spontaneous activity in the model network. Furthermore the strength of an afferent stimulation needed to disrupt delay-type activity increased with the magnitude of the dopamine-induced shifts in network parameters, making the currently active representation much more stable. Stability could be increased by dopamine-induced enhancements of the persistent Na(+) and N-methyl-D-aspartate (NMDA) conductances. Stability also was enhanced by a reduction in AMPA conductances. The increase in GABA(A) conductances that occurs after stimulation of dopaminergic D1 receptors was necessary in this context to prevent uncontrolled, spontaneous switches into high-activity states (i.e., spontaneous activation of task-irrelevant representations). In conclusion, the dopamine-induced changes in the biophysical properties of intrinsic ionic and synaptic conductances conjointly acted to highly increase stability of activated representations in PFC networks and at the same time retain control over network behavior and thus preserve its ability to adequately respond to task-related stimuli. Predictions of the model can be tested in vivo by locally applying specific D1 receptor, NMDA, or GABA(A) antagonists while recording from PFC neurons in delayed reaction-type tasks with interfering stimuli.