People face challenges with complex search tasks daily; chat-based large language models have the potential to assist search by helping with query formulation and content navigation, for instance. However, there is a lack of user research on integrating AI chat and traditional search to enhance Information Retrieval (IR) for the general public. This study explores how younger (25 participants) and older (22 participants) adults utilize these two platforms to retrieve information. Through two IR tasks, quality- and quantity-oriented tasks, focused on gathering evidence related to various countries’ CO 2 emissions, younger users spent more time, issued more queries, and explored more external web pages than older adults in both tasks. In contrast, despite reporting less familiarity with AI chat, older adults relied more on chat to complete their tasks. They submitted longer queries for the quality task and reached the first query faster for the quantity task than their younger counterparts, reflecting a top-down IR strategy. In the end, task outcomes were similar for the two groups, indicating AI chat’s capability to support IR. Drawing from our study results and relevant literature, we propose five design requirements to harness the synergic value of search and AI chat in supporting IR.

Electroencephalography (EEG) can enable non-invasive, real-time measurement of brain activity reflecting cognitive processes during human language processing. Previously released EEG datasets primarily capture brain signals recorded either during natural reading or within controlled psycholinguistic experimental settings. Given that information retrieval research depends on understanding and modelling relevance, we present a novel dataset including EEG data recorded while participants read text that is semantically relevant or irrelevant to self-selected topics. The dataset contains 23, 270 time-locked (∼ 0.7s) word-level EEG recordings. Using these data, we conduct benchmark experiments with two evaluation protocols, cross-subject and within-subject, focusing on two prediction tasks: word relevance and sentence relevance. We report the performance of five well known models on these tasks. Altogether, our dataset paves the way for advancing research on language relevance, brain input and feedback-based recommendation and retrieval systems, and development of brain-computer interface (BCI) devices for online detection of language relevance. Our dataset and code are openly released at https://osf.io/xh3g5/wiki/home/ and at HuggingFace https://huggingface.co/datasets/Quoron/EEG-semantic-text-relevance.

Researchers increasingly explore deploying brain-computer interfaces (BCIs) for able-bodied users, with the motivation of accessing mental states more directly than allowed by existing body-mediated interaction.This motivation seems to contradict the long-standing HCI emphasis on embodiment, namely the general claim that the body is crucial for cognition.This paper addresses this apparent contradiction through a review of insights from embodied cognition and interaction.We first critically examine the recent interest in BCIs and identify the extent cognition in the brain is integrated with the wider body as a central concern for research.We then define the implications of an integrated view of cognition for interface design and evaluation.A counterintuitive conclusion we draw is that embodiment per se should not imply a preference for body-mediated interaction over BCIs.It can instead guide research by 1) providing bodygrounded explanations for BCI performance, 2) proposing evaluation considerations that are neglected in modular views of cognition, and 3) through the direct transfer of its design insights to BCIs.We finally reflect on HCI's understanding of embodiment and identify the neural dimension of embodiment as hitherto overlooked.

Phantom tactile sensation (PTS) is usually experienced by participants in laboratory settings with the assistance and supervision of professionals. Extensive reports from users demonstrate they experience PTS on commercially available virtual reality (VR) platforms. We gathered and analyzed 2885 posts by 1408 users to understand how users obtain PTS and how they evaluate their PTS experience. We observed that users experience PTS in three ways: 1) starting to feel it naturally, 2) intentionally developing the ability to experience PTS, and 3) feeling it under substance use. Users perceive the sensation differently. Many people perceive PTS as positive, enhancing their immersion and bringing people closer. While other users consider it a negative experience as it exacerbates harassment issues, or the sensation itself is negative, even painful. We discuss the perceived causes of PTS and how social VR conditions users' evaluation of their PTS experience. We further reflect on PTS from the perspective of the risk of VR use in real-life scenarios. Finally, we provide design implications on employing PTS to enhance users' VR experience and reduce the negatives PTS brings.

Affective annotation refers to the process of labeling media content based on the emotions they evoke. Since such experiences are inherently subjective and depend on individual differences, the central challenge is associating digital content with its affective, interindividual experience. Here, we present a first-of-its-kind methodology for affective annotation directly from brain signals by monitoring the affective experience of a crowd of individuals via functional near-infrared spectroscopy (fNIRS). An experiment is reported in which fNIRS was recorded from 31 participants to develop a brain-computer interface (BCI) for affective annotation. Brain signals evoked by images were used to draw predictions about the affective dimensions that characterize the stimuli. By combining annotations, the results show that monitoring crowd responses can draw accurate affective annotations, with performance improving significantly with increases in crowd size. Our methodology demonstrates a proof-of-concept to source affective annotations from a crowd of BCI users without requiring any auxiliary mental or physical interaction.

We present a dataset for the analysis of human affective states using functional near-infrared spectroscopy (fNIRS). Data were recorded from thirty-one participants who engaged in two tasks. In the emotional perception task the participants passively viewed images sampled from the standard international affective picture system database, which provided ground-truth valence and arousal annotation for the stimuli. In the affective imagery task the participants actively imagined emotional scenarios followed by rating these for subjective valence and arousal. Correlates between the fNIRS signal and the valence-arousal ratings were investigated to estimate the validity of the dataset. Source-code and summaries are provided for a processing pipeline, brain activity group analysis, and estimating baseline classification performance. For classification, prediction experiments are conducted for single-trial 4-class classification of arousal and valence as well as cross-participant classifications, and comparisons between high and low arousal variants of the valence prediction tasks. Finally, classification results are presented for subject-specific and cross-participant models. The dataset is made publicly available to encourage research on affective decoding and downstream applications using fNIRS data.

Generative models are powerful tools for producing novel information by learning from example data. However, the current approaches require explicit manual input to steer generative models to match human goals. Furthermore, how these models would integrate implicit, diverse feedback and goals of multiple users remains largely unexplored. Here, we present a first-of-its-kind system that produces novel images of faces by inferring human goals directly from cross-subject brain signals while study subjects are looking at example images. We report on an experiment where brain responses to images of faces were recorded using electroencephalography in 30 subjects, focusing on specific salient visual features (VFs). Preferences toward VFs were decoded from subjects' brain responses and used as implicit feedback for a generative adversarial network (GAN), which generated new images of faces. The results from a follow-up user study evaluating the presence of the target salient VFs show that the images generated from brain feedback represent the goal of the study subjects and are comparable to images generated with manual feedback. The methodology provides a stepping stone toward humans-in-the-loop image generation.

The present notion of visual similarity is based on features derived from image contents. This ignores the users' emotional or affective experiences toward the content, and how users feel when they search for images. Here we consider valence, a positive or negative quantification of affective appraisal, as a novel dimension of image similarity. We report the largest neuroimaging experiment that quantifies and predicts the valence of visual content by using functional near-infrared spectroscopy from brain-computer interfacing. We show that affective similarity can be (1)~decoded directly from brain signals in response to visual stimuli, (2)~utilized for predicting affective image similarity with an average accuracy of 0.58 and an accuracy of 0.65 for high-arousal stimuli, and (3)~effectively used to complement affective similarity estimates of content-based models; for example when fused fNIRS and image rankings the retrieval F-measure@20 is 0.70. Our work opens new research avenues for affective multimedia analysis, retrieval, and user modeling.

Information retrieval (IR) relies on a general notion of relevance, which is used as the principal foundation for ranking and evaluation methods. However, IR does not account for more a nuanced affective experience. Here, we consider the emotional response decoded directly from the human brain as an alternative dimension of relevance. We report an experiment covering seven different scenarios in which we measure and predict how users emotionally respond to visual image contents by using functional near-infrared spectroscopy (fNIRS) neuroimaging on two commonly used affective dimensions: valence (negativity and positivity) and arousal (boredness and excitedness). Our results show that affective states can be successfully decoded using fNIRS, and utilized to complement the present notion of relevance in IR studies. For example, we achieved 0.39 Balanced accuracy and 0.61 AUC in 4-class classification of affective states (vs. 0.25 Balanced accuracy and 0.5 AUC of a random classifier). Likewise, we achieved 0.684 Precision@20 when retrieving high-arousal images. Our work opens new avenues for incorporating emotional states in IR evaluation, affective feedback, and information filtering.

Interpersonal touch is critical for social-emotional development and presents a powerful modality for communicating emotions. Virtual agents of the future could capitalize on touch to establish social bonds with humans and facilitate cooperation in virtual reality (VR). We studied whether the emotional expression of a virtual agent would affect the way humans touch the agent. Participants were asked to hold a pressure-sensing tube presented as the agent’s arm in VR. Upon seeing the agent’s emotional expression change, participants briefly squeezed the arm. The effect of emotional expressions on affective state was measured using self-reported valence and arousal as well as physiology-based indices. Onset, duration, and intensity of the squeeze were recorded to examine the haptic responses. Emotional expression of agents affected squeeze intensity and duration through changes in emotional perception and experience. Haptic responses may thus provide an implicit measure of persons’ experience towards their virtual companion.

Social touch is essential to human development and communication. Mediated social touch is suggested as a solution for circumstances where distance prevents skin-to-skin contact. However, past research aimed at demonstrating efficacy of mediated touch in reducing stress and promoting helping have produced mixed findings. These inconsistent findings could possibly be due to insufficient control of contextual factors combined with unnatural interaction scenarios. For example, touch occurs less frequently among strangers and is often accompanied with nonverbal visual cues. We investigated how visual presentation of touch, and interpersonal relationship to the sender influence perception, affective experiences, and autonomic responses the touch evoke. Fifty couples of mixed gender were recruited. A mediated touch was repeatedly applied by either the male partner or male confederate to female participants. The latter witnessed through a webcam as the sender caressed a rubber hand or touchpad to send the touch. Following our hypotheses, touch sent by one's partner was perceived softer and more comforting than stranger touch. The partner's touch also resulted in weaker skin conductance responses, particularly when sent by touching a touchpad. In sum, how a mediated touch is experienced depends both on who is touching, and on how the touch is visually represented.

We investigate inferring individual preferences and the contradiction of individual preferences with group preferences through direct measurement of the brain. We report an experiment where brain activity collected from 31 participants produced in response to viewing images is associated with their self-reported preferences. First, we show that brain responses present a graded response to preferences, and that brain responses alone can be used to train classifiers that reliably estimate preferences. Second, we show that brain responses reveal additional preference information that correlates with group preference, even when participants self-reported having no such preference. Our analysis of brain responses carries significant implications for researchers in general, as it suggests an individual's explicit preferences are not always aligned with the preferences inferred from their brain responses. These findings call into question the reliability of explicit and behavioral signals. They also imply that additional, multimodal sources of information may be necessary to infer reliable preference information.

While we instantaneously recognize a face as attractive, it is much harder to explain what exactly defines personal attraction. This suggests that attraction depends on implicit processing of complex, culturally and individually defined features. Generative adversarial neural networks (GANs), which learn to mimic complex data distributions, can potentially model subjective preferences unconstrained by pre-defined model parameterization. Here, we present generative brain-computer interfaces (GBCI), coupling GANs with brain-computer interfaces. GBCI first presents a selection of images and captures personalized attractiveness reactions toward the images via electroencephalography. These reactions are then used to control a GAN model, finding a representation that matches the features constituting an attractive image for an individual. We conducted an experiment (N = 30) to validate GBCI using a face-generating GAN and producing images that are hypothesized to be individually attractive. In double-blind evaluation of the GBCI-produced images against matched controls, we found GBCI yielded highly accurate results. Thus, the use of EEG responses to control a GAN presents a valid tool for interactive information-generation. Furthermore, the GBCI-derived images visually replicated known effects from social neuroscience, suggesting that the individually responsive, generative nature of GBCI provides a powerful, new tool in mapping individual differences and visualizing cognitive-affective processing.

Collaborative filtering is a common technique in which interaction data from a large number of users are used to recommend items to an individual that the individual may prefer but has not interacted with. Previous approaches have achieved this using a variety of behavioral signals, from dwell time and clickthrough rates to self-reported ratings. However, such signals are mere estimations of the real underlying preferences of the users. Here, we use brain-computer interfacing to infer preferences directly from the human brain. We then utilize these preferences in a collaborative filtering setting and report results from an experiment where brain inferred preferences are used in a neural collaborative filtering framework. Our results demonstrate, for the first time, that brain-computer interfacing can provide a viable alternative for behavioral and self-reported preferences in realistic recommendation scenarios. We also discuss the broader implications of our findings for personalization systems and user privacy.

This paper introduces brainsourcing: utilizing brain responses of a group of human contributors each performing a recognition task to determine classes of stimuli. We investigate to what extent it is possible to infer reliable class labels using data collected utilizing electroencephalography (EEG) from participants given a set of common stimuli. An experiment (N=30) measuring EEG responses to visual features of faces (gender, hair color, age, smile) revealed an improved F1 score of 0.94 for a crowd of twelve participants compared to an F1 score of 0.67 derived from individual participants and a random chance of 0.50. Our results demonstrate the methodological and pragmatic feasibility of brainsourcing in labeling tasks and opens avenues for more general applications using brain-computer interfacing in a crowdsourced setting.

Brain-computer interfaces (BCIs) are increasingly used to perform simple operations such as a moving a cursor, but have remained of limited use for more complex tasks. In our new approach to BCI, we use brain relevance feedback to control a generative adversarial network (GAN). We obtained EEG data from 31 participants who viewed face images while concentrating on particular facial features. Following, an EEG relevance classifier was trained and propagated as feedback on the latent image representation provided by the GAN. Estimates for individual vectors matching the relevant criteria were iteratively updated to optimize an image generation process towards mental targets. A double-blind evaluation showed high performance (86.26% accuracy) against random feedback (18.71%), and not significantly lower than explicit feedback (93.30%). Furthermore, we show the feasibility of the method with simultaneous task targets demonstrating BCI operation beyond individual task constraints. Thus, brain relevance feedback can validly control a generative model, overcoming a critical limitation of current BCI approaches.

Despite advances in the past few decades in studying what kind of queries users input to search engines and how to suggest queries for the users, the fundamental question of what makes human cognition able to estimate goodness of query terms is largely unanswered. For example, a person searching information about "cats'' is able to choose query terms, such as "housecat'', "feline'', or "animal'' and avoid terms like "similar'', "variety'', and "distinguish''. We investigated the association between the specificity of terms occurring in documents and human brain activity measured via electroencephalography (EEG). We analyzed the brain activity data of fifteen participants, recorded in response to reading terms from Wikipedia documents. Term specificity was shown to be associated with the amplitude of evoked brain responses. The results indicate that by being able to determine which terms carry maximal information about, and can best discriminate between, documents, people have the capability to enter good query terms. Moreover, our results suggest that the effective query term selection process, often observed in practical search behavior studies, has a neural basis. We believe our findings constitute an important step in revealing the cognitive processing behind query formulation and evaluating informativeness of language in general.

Virtual reality presents an extraordinary platform for multimodal communication. Haptic technologies have been shown to provide an important contribution to this by facilitating co-presence and allowing affective communication. However, the findings of the affective influences rely on studies that have used myriad different types of haptic technology, making it likely that some forms of tactile feedback are more efficient in communicating emotions than others. To find out whether this is true and which haptic technologies are most effective, we measured user experience during a communication scenario featuring an affective agent and interpersonal touch in virtual reality. Interpersonal touch was simulated using two types of vibrotactile actuators and two types of force feedback mechanisms. Self-reports of subjective experience of the agent’s touch and emotions were obtained. The results revealed that, regardless of the agent’s expression, force feedback actuators were rated as more natural and resulted in greater emotional interdependence and a stronger sense of co-presence than vibrotactile touch.

Peripheral physiological signals, as obtained using electrodermal activity and facial electromyography over the corrugator supercilii muscle, are explored as indicators of perceived relevance in information retrieval tasks. An experiment with 40 participants is reported, in which these physiological signals are recorded while participants perform information retrieval tasks. Appropriate feature engineering is defined, and the feature space is explored. The results indicate that features in the window of 4 to 6 seconds after the relevance judgment for electrodermal activity, and from 1 second before to 2 seconds after the relevance judgment for corrugator supercilii activity, are associated with the users' perceived relevance of information items. A classifier verified the predictive power of the features and showed up to 14% improvement predicting relevance. Our research can help the design of intelligent user interfaces for information retrieval that can detect the user's perceived relevance from physiological signals and complement or replace conventional relevance feedback.

Term-Relevance Prediction from Brain Signals (TRPB) is proposed to automatically detect relevance of text information directly from brain signals. An experiment with forty participants was conducted to record neural activity of participants while providing relevance judgments to text stimuli for a given topic. High-precision scientific equipment was used to quantify neural activity across 32 electroencephalography (EEG) channels. A classifier based on a multi-view EEG feature representation showed improvement up to 17% in relevance prediction based on brain signals alone. Relevance was also associated with brain activity with significant changes in certain brain areas. Consequently, TRPB is based on changes identified in specific brain areas and does not require user-specific training or calibration. Hence, relevance predictions can be conducted for unseen content and unseen participants. As an application of TRPB we demonstrate a high-precision variant of the classifier that constructs sets of relevant terms for a given unknown topic of interest. Our research shows that detecting relevance from brain signals is possible and allows the acquisition of relevance judgments without a need to observe any other user interaction. This suggests that TRPB could be used in combination or as an alternative for conventional implicit feedback signals, such as dwell time or click-through activity.