Stimulus Display Research Articles

Inducing select/reject control in a matching-to-sample procedure with observing response: Effects on stimulus equivalence.

This study investigated a three-choice matching-to-sample procedure with an observing-response requirement to induce select and reject control during baseline training and examined their effects on the formation of equivalence classes. The study involved four girls, aged 8 to 10 years, who participated in a computer-based task that alternated between conditions designed to induce select and reject control by requiring observing responses to display the stimuli. In the select-control condition, the correct stimulus was revealed first on at least 75% of the trials, increasing the likelihood of selecting the correct stimulus without seeing the incorrect ones. In contrast, in the reject-control condition, the correct stimulus was revealed third on at least 75% of the trials, forcing the display of both incorrect stimuli. This procedure successfully generated both select and reject control, which increased progressively with the accuracy during baseline training trials. Select control was more prominent than reject control, but both led to the formation of equivalence classes. This finding suggests that reject control does not hinder control by the correct stimulus.

Type of auditory cues and apparatus influence how healthy young adults integrate sounds for dynamic balance.

It is unclear whether the brain handles auditory cues similarly to visual cues for balance. We investigated the influence of headphones and loudspeaker reproduction of sounds on dynamic balance performance when an individual is facing a cognitive challenge. Twenty participants (16 females, aged 19-36) were asked to avoid a ball according to a specific visual rule. Visuals were projected from the HTC Vive head-mounted display in an acoustically controlled space. We varied the environment by adding congruent sounds (sounds coincide with the visual rule) or incongruent sounds (sounds may or may not coincide with the visual rule) as well as creating a multimodal (visual and congruent sounds) vs. unimodal (visual or congruent sounds only) display of stimuli. Sounds were played over headphones or loudspeakers. We quantified reaction time (RT) and accuracy (choosing the correct direction to move) by capturing the head movement. We found that in the absence of sounds, RT was slower with headphones compared to loudspeakers, but the introduction of either congruent or incongruent sounds resulted in faster movements with headphones such that RT was no longer different between apparatus. Participants used congruent sounds to improve accuracy but disregarded incongruent sounds. This suggests that selective attention may explain how sounds are incorporated into dynamic balance performance in healthy young adults. Participants leveraged sounds played over loudspeakers, but not over headphones, to enhance accuracy in a unimodal dark environment. This may be explained by the natural listening conditions created by loudspeakers where sounds may be perceived as externalized.

On the origin of the Ponzo illusion: An attentional account.

The Ponzo illusion is a famous optical illusion that is not well understood so far. Here we suggest that its origin is closely linked to distribution of spatial attention. In essence, it arises because the size of the attentional field varies between different parts of the stimulus layout, which comes with different spatial resolution and, as a consequence, different apparent sizes of the objects in the stimulus display. We report four experiments (conducted in 2022 and 2023), which support this approach. The illusion substantially decreases when the stimulus layout is modified so that the size of the supposed attentional field is equalized for the crucial parts (Experiment 1). Moreover, we induce a Ponzo-like illusion by means of attentional cues only (Experiment 2). The perceived spatial frequency differs for different parts of the stimulus layout consistent with predicted changes in spatial resolution (Experiment 3). Attentional cuing exerts an analogous influence on the apparent spatial frequency (Experiment 4). The presented approach provides a novel look at the origin of the Ponzo illusion and related phenomena. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Wireless Heart Sensor for Capturing Cardiac Orienting Response for Prediction of Neurodevelopmental Delay in Infants.

Early identification of infants at risk of neurodevelopmental delay is an essential public health aim. Such a diagnosis allows early interventions for infants that maximally take advantage of the neural plasticity in the developing brain. Using standardized physiological developmental tests, such as the assessment of neurophysiological response to environmental events using cardiac orienting responses (CORs), is a promising and effective approach for early recognition of neurodevelopmental delay. Previous CORs have been collected on children using large bulky equipment that would not be feasible for widespread screening in routine clinical visits. We developed a portable wireless electrocardiogram (ECG) system along with a custom application for IOS tablets that, in tandem, can extract CORs with sufficient physiologic and timing accuracy to reflect the well-characterized ECG response to both auditory and visual stimuli. The sensor described here serves as an initial step in determining the extent to which COR tools are cost-effective for the early screening of children to determine who is at risk of developing neurocognitive deficits and may benefit from early interventions. We demonstrated that our approach, based on a wireless heartbeat sensor system and a custom mobile application for stimulus display and data recording, is sufficient to capture CORs from infants. The COR monitoring approach described here with mobile technology is an example of a desired standardized physiologic assessment that is a cost-and-time efficient, scalable method for early recognition of neurodevelopmental delay.

Unlocking crowding by ensemble statistics

In crowding,1,2,3,4,5,6,7 objects that can be easily recognized in isolation appear jumbled when surrounded by other elements.8 Traditionally, crowding is explained by local pooling mechanisms,3,6,9,10,11,12,13,14,15 but many findings have shown that the global configuration of the entire stimulus display, rather than local aspects, determines crowding.8,16,17,18,19,20,21,22,23,24,25,26,27,28 However, understanding global configurations is challenging because even slight changes can lead from crowding to uncrowding and vice versa.23,25,28,29 Unfortunately, the number of configurations to explore is virtually infinite. Here, we show that one does not need to know the specific configuration of flankers to determine crowding strength but only their ensemble statistics, which allow for the rapid computation of groups within the stimulus display.30,31,32,33,34,35,36,37 To investigate the role of ensemble statistics in (un)crowding, we used a classic vernier offset discrimination task in which the vernier was flanked by multiple squares. We manipulated the orientation statistics of the squares based on the following rationale: a central square with an orientation different from the mean orientation of the other squares stands out from the rest and groups with the vernier, causing strong crowding. If, on the other hand, all squares group together, the vernier is the only element that stands out, and crowding is weak. These effects should depend exclusively on the perceived ensemble statistics, i.e., on the mean orientation of the squares and not on their individual orientations. In two experiments, we confirmed these predictions.

Interocular suppression in primary visual cortex in strabismus: impact of staggering the presentation of stimuli to the eyes.

Diplopia (double vision) in strabismus is prevented by suppression of the image emanating from one eye. In a recent study conducted in two macaques raised with exotropia (an outward ocular deviation) but having normal acuity in each eye, simultaneous display of stimuli to each eye did not induce suppression in V1 neurons. Puzzled by this negative result, we have modified our protocol to display stimuli in a staggered sequence, rather than simultaneously. Additional recordings were made in the same two macaques, following two paradigms. In trial type 1, the receptive field in one eye was stimulated with a sine-wave grating while the other eye was occluded. After 5 s, the occluder was removed and the neuron was stimulated for another 5 s. The effect of uncovering the eye, which potentially exposed the animal to diplopia, was quantified by the peripheral retinal interaction index (PRII). In trial type 2, the receptive field in the fixating eye was stimulated with a grating during binocular viewing. After 5 s, a second grating appeared in the receptive field of the nonfixating eye. The impact of the second grating, which had the potential to generate visual confusion, was quantified by the receptive field interaction index (RFII). For 82 units, the mean PRII was 0.48 ± 0.05 (0.50 = no suppression) and the mean RFII was 0.46 ± 0.08 (0.50 = no suppression). These values suggest mild suppression, but the modest decline in spike rate registered during the second epoch of visual stimulation might have been due to neuronal adaptation, rather than interocular suppression. In a few instances neurons showed unequivocal suppression, but overall, these recordings did not support the contention that staggered stimulus presentation is more effective than simultaneous stimulus presentation at evoking interocular suppression in V1 neurons.NEW & NOTEWORTHY In strabismus, double vision is prevented by interocular suppression. It has been reported that inhibition of neuronal firing in the primary visual cortex occurs only when stimuli are presented sequentially, rather than simultaneously. However, these recordings in alert macaques raised with exotropia showed, with rare exceptions, little evidence to support the concept that staggered stimulus presentation is more effective at inducing interocular suppression of V1 neurons.

How to build a fast and accurate code-modulated brain-computer interface

Objective. In the last decade, the advent of code-modulated brain-computer interfaces (BCIs) has allowed the implementation of systems with high information transfer rates (ITRs) and increased the possible practicality of such interfaces. In this paper, we evaluate the effect of different numbers of targets in the stimulus display, modulation sequences generators, and signal processing algorithms on the accuracy and ITR of code-modulated BCIs. Approach. We use both real and simulated electroencephalographic (EEG) data, to evaluate these parameters and methods. Then, we compared numerous different setups to assess their performance and identify the best configurations. We also evaluated the dependability of our simulated evaluation approach. Main results. Our results show that Golay, almost perfect, and deBruijn sequence-based visual stimulus modulations provide the best results, significantly outperforming the commonly used m-sequences in all cases. We conclude that artificial neural network processing algorithms offer the best processing pipeline for this type of BCI, achieving a maximum classification accuracy of 94.7% on real EEG data while obtaining a maximum ITR of 127.2 bits min−1 in a simulated 64-target system. Significance. We used a simulated framework that demonstrated previously unattainable flexibility and convenience while staying reasonably realistic. Furthermore, our findings suggest several new considerations which can be used to guide further code-based BCI development.

101 Measurement of Tapping During the Interstimulus Interval as a Validation Metric for the 3-Minute Psychomotor Vigilance Test

Abstract Introduction The Psychomotor Vigilance Test is a well-validated measure of sustained attention used to assess daytime alertness in sleep research studies.1 It is commonly used in a variety of research settings due to its high sensitivity to sleep loss and absence of learning effects,2 making it an ideal tool to assess objective alertness. As some types of sleep research transition out of controlled laboratory environments, tools like the PVT require modification to maximize their reliability. The validation of the 3-minute version (PVT-B) against the 10-minute PVT is an example of this modification.3 However, considerable work is needed to improve trust in the utility of the PVT-B in and outside of traditional laboratory settings. Methods We carefully analyzed data from a mobile-based version of the PVT-B, noting responses that occurred during the interstimulus interval which were termed “wrong taps.” Wrong taps indicated that participants were not performing the task as instructed. In some cases, wrong taps occurred across multiple trials of the same PVT block, indicative of participants repeatedly tapping the screen throughout the task to minimize response times. A comprehensive examination of wrong taps was carried out in order to identify instances where this pattern emerged. Results A total of 1,338,538 PVT-B trials from 7,028 participants were examined to determine the number of wrong taps present across all trials. While 91.7% of PVT-B trials were free of wrong taps, 8.3% of PVT-B trials contained 1 or more wrong taps and 5.2% contained 2 or more wrong taps. It appears that a maximum of one wrong tap per trial is acceptable and trials containing 2 or more should be excluded to maximize PVT data quality. Conclusion Utilizing a metric like wrong taps can help identify individuals taking the PVT-B who are tapping the screen multiple times prior to stimulus display. Closely examining this metric can help to ensure the validity of PVT-B administrations. Two possible uses of the metric could be to provide feedback during training trials and to remove trials where this strategy was employed. Support (if any) This analysis was supported by the VA San Diego Healthcare System Research Service.

Wisdom of crowds benefits perceptual decision making across difficulty levels

Decades of research on collective decision making has claimed that aggregated judgment of multiple individuals is more accurate than expert individual judgement. A longstanding problem in this regard has been to determine how decisions of individuals can be combined to form intelligent group decisions. Our study consisted of a random target detection task in natural scenes, where human subjects (18 subjects, 7 female) detected the presence or absence of a random target as indicated by the cue word displayed prior to stimulus display. Concurrently the neural activities (EEG signals) were recorded. A separate behavioural experiment was performed by different subjects (20 subjects, 11 female) on the same set of images to categorize the tasks according to their difficulty levels. We demonstrate that the weighted average of individual decision confidence/neural decision variables produces significantly better performance than the frequently used majority pooling algorithm. Further, the classification error rates from individual judgement were found to increase with increasing task difficulty. This error could be significantly reduced upon combining the individual decisions using group aggregation rules. Using statistical tests, we show that combining all available participants is unnecessary to achieve minimum classification error rate. We also try to explore if group aggregation benefits depend on the correlation between the individual judgements of the group and our results seem to suggest that reduced inter-subject correlation can improve collective decision making for a fixed difficulty level.

Local biases drive, but do not determine, the perception of illusory trajectories

When a dot moves horizontally across a set of tilted lines of alternating orientations, the dot appears to be moving up and down along its trajectory. This perceptual phenomenon, known as the slalom illusion, reveals a mismatch between the veridical motion signals and the subjective percept of the motion trajectory, which has not been comprehensively explained. In the present study, we investigated the empirical boundaries of the slalom illusion using psychophysical methods. The phenomenon was found to occur both under conditions of smooth pursuit eye movements and constant fixation, and to be consistently amplified by intermittently occluding the dot trajectory. When the motion direction of the dot was not constant, however, the stimulus display did not elicit the expected illusory percept. These findings confirm that a local bias towards perpendicularity at the intersection points between the dot trajectory and the tilted lines cause the illusion, but also highlight that higher-level cortical processes are involved in interpreting and amplifying the biased local motion signals into a global illusion of trajectory perception.

Exploring the Extent in the Visual Field of the Honeycomb and Extinction Illusions.

There are situations in which what is perceived in central vision is different to what is perceived in the periphery, even though the stimulus display is uniform. Here, we studied two cases, known as the Extinction illusion and the Honeycomb illusion, involving small disks and lines, respectively, presented over a large extent of the visual field. Disks and lines are visible in the periphery on their own, but they become invisible when they are presented as part of a pattern (grid). Observers (N = 56) adjusted a circular probe to report the size of the region in which they had seen the lines or the disks. Different images had black or white lines/disks, and we included control stimuli in which these features were spatially separated from the regular grid of squares. We confirmed that the illusion was experienced by the majority of observers and is dependent on the interaction between the elements (i.e., the lines/disks have to be near the squares). We found a dissociation between the two illusions in the dependence on contrast polarity suggesting different mechanisms. We analysed the variability between individuals with respect to schizotypical and autistic-spectrum traits (short version of the Oxford-Liverpool Inventory of Feelings and Experiences [O-LIFE] questionnaire and the Autistic Quotient, respectively) but found no significant relationships. We discuss how illusions relative to what observers are aware of in the periphery may offer a unique tool to study visual awareness.

Independence of viewpoint and identity in face ensemble processing.

Ensemble encoding refers to the visual system's ability to extract a summary representation from multiple items in a set-such as the mean identity of faces in a crowd-circumventing capacity limitations in visual working memory. In the present study we investigated face ensemble representations of higher level identity and lower level viewpoint with the aim of elucidating the extent of their overlap or independence. To this end, we used ensemble displays consisting of six face stimuli which could vary in identity, viewpoint, or both. Across three experiments, participants were asked to report an average identity, a single identity, an average viewpoint, or a single viewpoint, as cued by a central probe face following a stimulus display. In Experiment 1, we observed a dissociation between the processing of identity and viewpoint, as well as between average- and single-viewpoint extraction. Experiment 2 showed viewpoint-invariant identity processing across a wide range of mean viewpoints, spanning 120°. In Experiment 3, accuracy in reporting a response-relevant attribute was unaffected by changes in an irrelevant attribute. Participants were also capable of extracting both attributes simultaneously with little change in accuracy. Taken together, these results argue for the independence of identity and viewpoint in face ensemble processing.

(Invited) Interactive Skin Display with Epidermal Stimuli Electrode

In addition to the demand for stimuli-responsive sensors that can detect various vital signals in epidermal skin, the development of electronic skin displays that quantitatively detect and visualize various epidermal stimuli such as the temperature, sweat gland activity, and conductance simultaneously are of significant interest for emerging human-interactive electronics used in health-monitoring [1,2]. First of all, shape-deformable and self-healing EL displays (SSELD) are presented. Light emitting materials are fabricated by adding a certain amount of a plasticizer to elastomer containing light-emitting phosphors to obtain a viscoelastic composite that undergoes facile shape-deformation and recovery. A capacitive SSELD exhibits frequency-dependent field-induced light emission under alternating current (AC). A SSELD self-recovers its EL within few minutes of electrical failure with more than 100 cycles of failure-recovery operation endurance. By combining with a shape-deformable ionic liquid, a novel fiber display which exhibits excellent shape-deformable and self-healing EL performance. Second, a novel interactive skin display with epidermal stimuli electrode (ISDEE) is demonstrated, allowing for the simultaneous sensing and display of multiple epidermal stimuli on a single device. It is based on a simple two-layer architecture on a topographically patterned elastomeric polymer composite with light-emitting inorganic phosphors, upon which two electrodes are placed with a certain parallel gap. The ISDEE is directly mounted on human skin, which by itself serves as a field-responsive floating electrode of the display operating under AC. The AC field exerted on the epidermal skin layer depends on the conductance of the skin, which can be modulated based on a variety of physiological skin factors, such as the temperature, sweat gland activity, and pressure. Conductance-dependent field-induced electroluminescence is achieved, giving rise to an on-hand sensing display platform where we can directly sense and visualize a variety of human information.

Between one event and two: The locus of the effect of stimulus contrast on temporal integration.

The effects of relative stimulus contrast on temporal integration were investigated in a missing element task. Integration frequency was strongly modulated when the contrast of either the first or the second stimulus display was reduced. When the contrast of the first display was low, integration was enhanced, while it was reduced when the contrast of the second display was low. To reveal the processing phases implicated in these modulations of integration, the amplitude of ERP components was examined. N1 component amplitude was increased when the second display was low contrast, matching a full contrast condition. At the N2pc component, amplitude was strongly suppressed only in the former condition. P3 amplitude was also lowest when contrast on the second display was low but with successively increasing amplitudes observed for the other conditions, largely matching the pattern observed in behavioral performance. Taken together, contrast effects on temporal integration seem to originate from increased discriminative processing of the first stimulus display in particular (N1), which is consequently followed by an impairment in attentional processing (N2pc) and working memory consolidation (P3) of the missing element location.

Interactive Skin Display with Epidermal Stimuli Electrode.

In addition to the demand for stimuli‐responsive sensors that can detect various vital signals in epidermal skin, the development of electronic skin displays that quantitatively detect and visualize various epidermal stimuli such as the temperature, sweat gland activity, and conductance simultaneously are of significant interest for emerging human‐interactive electronics used in health monitoring. Herein, a novel interactive skin display with epidermal stimuli electrode (ISDEE) allowing for the simultaneous sensing and display of multiple epidermal stimuli on a single device is presented. It is based on a simple two‐layer architecture on a topographically patterned elastomeric polymer composite with light‐emitting inorganic phosphors, upon which two electrodes are placed with a certain parallel gap. The ISDEE is directly mounted on human skin, which by itself serves as a field‐responsive floating electrode of the display operating under an alternating current (AC). The AC field exerted on the epidermal skin layer depends on the conductance of the skin, which can be modulated based on a variety of physiological skin factors, such as the temperature, sweat gland activity, and pressure. Conductance‐dependent field‐induced electroluminescence is achieved, giving rise to an on‐hand sensing display platform where a variety of human information can be directly sensed and visualized.

Decoding motion direction using the topography of sustained ERPs and alpha oscillations

The present study sought to determine whether scalp electroencephalogram (EEG) signals contain decodable information about the direction of motion in random dot kinematograms (RDKs), in which the motion information is spatially distributed and mixed with random noise. Any direction of motion from 0 to 360° was possible, and observers reported the precise direction of motion at the end of a 1500-ms stimulus display. We decoded the direction of motion separately during the motion period (during which motion information was being accumulated) and the report period (during which a shift of attention was necessary to make a fine-tuned direction report). Machine learning was used to decode the precise direction of motion (within ±11.25°) from the scalp distribution of either alpha-band EEG activity or sustained event-related potentials (ERPs). We found that ERP-based decoding was above chance (1/16) during both the stimulus and the report periods, whereas alpha-based decoding was above chance only during the report period. Thus, sustained ERPs contain information about spatially distributed direction-of-motion, providing a new method for observing the accumulation of sensory information with high temporal resolution. By contrast, the scalp topography of alpha-band EEG activity appeared to mainly reflect spatially focused attentional processes rather than sensory information.

Response Preparation With Reliable Cues Decreases Response Competition in the Flanker Task.

We tested the hypothesis that selective response preparation, based on reliable response cues, reduces response conflict in an Eriksen flanker task. Previous studies of this issue produced inconclusive results because presenting an always valid response cue before the stimulus display turns a choice-response task into a simple-response task, in which full processing of the actual stimulus display is no longer necessary. We conducted two experiments in which we matched stimulus processing in conditions without cues and with reliable cues as far as possible. In both experiments, we presented a nogo target stimulus in 25% of the trials. The different cueing conditions were presented in separate blocks in Experiment 1 but mixed within blocks in Experiment 2. The most important result was the reduction of response conflict as induced by incompatible flanker stimuli in both experiments with reliable response cues. This finding supports the notion of a negative preparation-interference relationship.

When the Good Looks Bad: An Experimental Exploration of the Repulsion Effect

When people are choosing among different options, context seems to play a vital role. For instance, adding a third option can increase the probability of choosing a similar dominating option. This attraction effect is one of the most widely studied phenomena in decision-making research. Its prevalence, however, has been challenged recently by the tainting hypothesis, according to which the inferior option contaminates the attribute space in which it is located, leading to a repulsion effect. In an attempt to test the tainting hypothesis and explore the conditions under which dominated options make dominating options look bad, we conducted four preregistered perceptual decision-making studies with a total of 301 participants. We identified two factors influencing individuals’ behavior: stimulus display and stimulus design. Our results contribute to a growing body of literature showing how presentation format influences behavior in preferential and perceptual decision-making tasks.

Implicit relational learning in a multiple-object tracking task

We studied implicit relational learning by embedding contextual relational information into a multiple-object tracking task. In two experiments, participants were instructed to track two or four out of eight moving objects and report at the end of the trial whether a single cued object was among those they tracked (yes/no task). The stimulus display also contained two background strips of different width. In the informative condition, the location of the cued object predicted the correct choice: If the answer was "yes", then the cued object was always located next to the narrower strip; otherwise, it was always located next to the wider strip (or vice versa). In the random condition, the location of the object did not predict the correct choice. Participants in the informative condition consistently displayed lower tracking accuracy than in the random condition, possibly due to attentional demands introduced by implicit relational task. At the same time, participants in the informative condition demonstrated no awareness of the task structure; instead, their reports were consistent with the attempts to track moving objects. Our task can provide a suitable model for studying implicit relational learning in adult participants that is essential for establishing generality of factors affecting relational learning.

Transient Signals and Inattentional Blindness in a Multi-object Tracking Task.

Inattentional blindness is a failure to notice an unexpected event when attention is directed elsewhere. The current study examined participants’ awareness of an unexpected object that maintained luminance contrast, switched the luminance once, or repetitively flashed. One hundred twenty participants performed a dynamic tracking task on a computer monitor for which they were instructed to count the number of movement deflections of an attended set of objects while ignoring other objects. On the critical trial, an unexpected cross that did not change its luminance (control condition), switched its luminance once (switch condition), or repetitively flashed (flash condition) traveled across the stimulus display. Participants noticed the unexpected cross more frequently when the luminance feature matched their attention set than when it did not match. Unexpectedly, however, a proportion of the participants who noticed the cross in the switch and flash conditions were statistically comparable. The results suggest that an unexpected object with even a single luminance change can break inattentional blindness in a multi-object tracking task.