Forced Choice Research Articles

Improving Reproductive Success in Captive Marmosets Through Active Female Choice

ABSTRACTThe recent upsurge in the use of common marmosets (Callithrix jacchus) as a desirable model for high‐priority biomedical research has challenged local and global suppliers struggling to provide sufficient numbers of marmosets for large‐scale projects. In laboratories, random male‐female pairings are often unsuccessful, with intervals of several months before attempting alternate pairings. Here we address this challenge through a behavioral task that promotes self‐directed female selection of potential mates to increase the efficiency of breeding in captive marmosets. We created a partner preference test in which nulliparous females (n = 12) had the opportunity to select between two eligible males (n = 23) at a time, in a forced choice test. In this test, both males and females displayed sexual solicitations. However, the females displayed a clear preference for one male by directing affiliative behaviors toward him including proceptive tongue‐flicking, approach, and grooming. Her preference remained consistent across three consecutive test sessions. This method resulted in a 2.5‐fold improvement in breeding success within 90 days compared to random pairings. This cost‐effective and straightforward pairing practice can be used to enhance breeding efficiency in both small and large marmoset colonies.

Perceptions of Mental Health and Mental Health Care in Luxembourg: A High-Income Country

AbstractMental health care in high-income countries can have various rates of usage due to differences in accessibility, modality of psychotherapy, and potential stigma surrounding mental health (Alonso et al., 2004). This study aimed to explore perceptions of mental health and mental health care, stigma for mental illness, and perceived change in mental health due to COVID − 19 pandemic in a high-income country with relatively easy access to basic mental health care. An anonymous survey was sent to individuals who are 18 years and older and resident of Luxembourg, a small country in Europe (N = 56). Participants were asked a series of open-ended and forced choice questions. Descriptive statistics were calculated for forced-choice questions and inductive content analysis was used to analyze the open-ended responses. Participants defined mental health in a variety of different ways, and a majority reported receiving mental health services. There was no significant difference in participants’ ratings of mental health before and during the COVID-19 pandemic. Mental health professionals were relatively easy to find and were considered somewhat helpful, though participants also reported some stigma towards mental illness. Benefits and challenges of in-person and virtual therapy showed points of crossover and potential for further research. The current findings inform the broader literature on mental healthcare with implications for improving care in high-income countries.

Intracortical microstimulation of human somatosensory cortex induces natural perceptual biases

Time-order error, a psychophysical phenomenon in which the duration in between successive stimuli alters perception, has been studied for decades by neuroscientists and psychologists. To date, however, the locus of these effects is unknown. We use intracortical microstimulation of somatosensory cortex in three humans with spinal cord injury as a tool to bypass initial stages of processing and restrict the possible locations that signals could be modified. Using a 2-interval forced choice amplitude discrimination paradigm, we first assessed the extent to which order effects are observed. Comparing trials where the standard stimulus was in the first or second interval, we found that systematic biases are exhibited, typically causing the intensity of the second stimulus to be overestimated The degree of this overestimation for individual electrodes was dependent on the perceptual sensitivity to changes in stimulus amplitude. To investigate the role of memory on this phenomenon, we implemented a 2-interval magnitude estimation task in which participants were instructed to ignore the first stimulus and again found that the perceptual intensity of the second stimulus tended to be enhanced by the first in a manner that depended on the amplitude and duration of the first stimulus. Finally, we repeated both paradigms while varying the inter-stimulus interval to examine the timescale over which these effects occur and found that longer inter-stimulus intervals reduced the effect size. These results show that direct activation of primary somatosensory cortex is sufficient to induce time-order errors.

Vocal Emotion Perception in Children Using Cochlear Implant.

The significance of emotional prosody in social communication is well-established, yet research on emotion perception among cochlear implant (CI) users is less extensive. This study aims to explore vocal emotion perception in children using CI and bimodal hearing devices and compare them with their normal hearing (NH) peers. The study involved children aged 4-10 years with unilateral CI and contralateral hearing aid (HA), matched with NH peers by gender and listening age. Children were selected using snowball sampling for the CI group and purposive sampling for the NH group. Vocal emotion perception was assessed for semantically neutral sentences in "happy," "sad," and "angry" emotions using a 3 alternate forced choice test. The NH group demonstrated significantly superior emotion perception (P=.002) compared to the CI group. Both groups accurately identified the "happy" emotion. However, the NH group had higher scores for the "angry" emotion compared to the "sad" emotion, while the CI group showed better scores for "sad" than "angry" emotion. Bimodal hearing devices improved recognition of "sad"and "angry" emotions, with a decrease in confusion percentages. The unbiased hit (Hu) value provided more substantial insight than the hit score. Bimodal hearing devices enhance the perception of "sad" and "angry" vocal emotions compared to using a CI alone, likely due to the HA providing the temporal fine structure cues, thereby better representing fundamental frequency variations. Children with unilateral CI benefit significantly in the perception of emotions by using a HA in the contralateral ear, aiding in better socio-emotional development.

Long-term retention of real-world experiences in a patient with profound amnesia

The medial temporal lobe (MTL) is known to be critical for healthy memory function, but patients with MTL damage can, under certain circumstances, demonstrate successful learning of novel information encountered outside the laboratory. Here, we describe a patient, D.C., with extensive but focal bilateral MTL damage centering primarily on his hippocampus, whose memory for real-world experiences was assessed. Tests of remote memory indicated at least some capacity to retrieve specific details. To test his anterograde memory, he was taken on a tour of the NIH Clinical Center, with unique events occurring at each of ten specific locations. His memory for these events was tested after 1 h, and again after fifteen months. Initially, D.C. could not recall having participated in the tour, even when cued with photographs of specific places he had visited. However, he achieved 90% accuracy on a forced choice recognition test of old and new objects he encountered on the tour, and his recognition of these objects remained intact over a year later when he was tested once again. Subsequent recognition memory tests using novel picture stimuli in a standard laboratory-style computer task resulted in chance-level performance across multiple test formats and stimulus categories. These findings suggest a potentially privileged role for natural learning for long-term retention in a patient with severely damaged medial temporal lobes.

Exploring the impact of screencast-based ipsative assessment on EFL students’ writing development

Screencast technology in English writing assessment offers personalized, detailed feedback, but not dialogic. However, integrating it with ipsative assessment (IA) principles may sustain conversations between teachers and learners on students’ writing development. This study explored the impact of screencast-based ipsative assessment (SIA) on developing students’ writing skills in an Iranian EFL context. Screencast technology recorded teachers’ feedback and facilitated students’ access to and reflection on their previous works. A qualitative research design was used to analyze teacher’s feedback profiles and students’ reflections. The findings revealed that SIA engaged participants in ipsative self-assessment, enhanced their self-regulation skills in writing, and created a comforting and socially safe environment where they felt supported and encouraged to take risks, knowing that their mistakes could be considered part of the learning process. However, SIA caused some students to focus on their scores rather than skill development in their writing tasks. The findings suggest that English teachers can utilize screencast technology for precise, detailed ipsative feedback in an IA regime. SIA procedures may encourage student self-assessment and foster a dialog between teachers and students to seek clarification and plan their next move in writing progress.

Flexible and Transparent Electrovibration-Based Haptic Display with Low Driving Voltage.

Electrovibration haptic technology, which provides tactile feedback to users by swiping the surface with a finger via electroadhesion, shows promise as a haptic feedback platform for displays owing to its simple structure, ease of integration with existing displays, and simple driving mechanism. However, without electrical grounding on a user's body, the frequent requirement of a high driving voltage near 50 V limits the use of electrovibration haptic technology in practical display applications. This study introduces materials and fabrication strategies that considerably reduce the driving voltage. We used a transparent poly(vinylidene fluoride) (PVDF) thin film deposited on transparent conductive polymers through a simple spin-coating process, thereby enabling easy integration with existing display technologies. The high dielectric constant characteristics of PVDF enabled the production of tactile cues at low voltages (approximately 15 V), which are within the safety limits of common electronics. We verified the feasibility of our electrovibration haptic feedback system on the basis of the absolute threshold voltage through two-alternative forced choice psychological tests. The results revealed that the PVDF dielectric layer exhibited a relatively lower absolute threshold than commonly used polymer films, which possess a relatively lower dielectric constant. To validate the tactile attributes, a Likert five-point scale survey was conducted, considering flat, concave, and convex curvatures. The results indicated that our haptic device can render diverse surface textures, such as "hairy" and "groovy", on the fingertips through the control of applied pulse width modulated voltage signals.

The problem with two-event sequence learning by pigeons

Bonobos appear to show little evidence of learning to make one response (R1) to an AB sequence and a different response (R2) to sequences BB, AA, and BA (Lind et al. PLoS ONE 18(9):e0290546, 2023), yet under different conditions, pigeons can learn this (Weisman et al. Exp Psychol Anim Behav Process 6(4):312, 1980). Aspects of the bonobo procedure may have contributed to this failure. Most important, no response was required in the presence of the stimuli to encourage attention to them. Furthermore, learning to make one response to the target sequence and another to the other sequences involves a bias that allows for better than chance responding. With the two-alternative forced-choice procedure used with the bonobos, the R1 response is correct for one sequence, whereas the R2 response is correct for three sequences. To correct for this, there are three times as many AB trials as each of the other sequences. However, this correction allows a bias to develop in which reinforcement often can be obtained by using only the last stimulus seen as the basis of choice (e.g., when the last stimulus is B respond R1 when the last stimulus is A respond R2). This solution yields reinforcement on five out of six, or 83%, of the trials. In the present experiment with pigeons, using this two-alternative forced choice procedure, most subjects tended to base their choice on the last-seen stimulus. This design allowed subjects to use a suboptimal but relatively effective choice strategy.

Sensory Discrimination Tests for Low- and High-Strength Alcohol

Research is limited on consumers’ ability to detect perceptible sensory differences between low- and high-strength alcoholic beverages. This study, therefore, conducted three pilot experiments using ISO sensory analysis methods to assess accuracy for evaluating beverages of different strengths. Participants were food production professionals trained in sensory analysis. Experiment 1 used a wide-range discrimination test to estimate low- to high-strength beverages (0–60% alcohol by volume (ABV) in 10% intervals). Experiment 2 included a narrower range of intermediate to high strengths (25–45% ABV in 5% intervals). Experiment 3 used 3-alternative forced choice tests (ISO 13301) to discriminate between beverages of varying strengths. Experiment 1 (n = 16) indicated that estimation ability was dependent upon the beverages’ ABV; as ABV increased, estimation significantly decreased (p < 0.005). These findings were not replicated in Experiment 2 (n = 13). In Experiment 3 (n = 17), a significant perceptible difference between high- and low-strength samples was observed in two of nine conditions (35% vs. 31% ABV (p = 0.009); 41% vs. 37% ABV (p = 0.037)). While people can detect large differences in beverage ABVs, they may have a moderate to poor ability to discriminate between beverages of similar strengths. These findings provide support for public health interventions that promote lower-strength alcoholic beverages.

Simultaneous modulation of pulse charge and burst period elicits two differentiable referred sensations

Objective.To investigate the feasibility of delivering multidimensional feedback using a single channel of peripheral nerve stimulation by complementing intensity percepts with flutter frequency percepts controlled by burst period modulation.Approach.Two dimensions of a distally referred sensation were provided simultaneously: intensity was conveyed by the modulation of the pulse charge rate inside short discrete periods of stimulation referred to as bursts and frequency was conveyed by the modulation of the period between bursts. For this approach to be feasible, intensity percepts must be perceived independently of frequency percepts. Two experiments investigated these interactions. A series of two alternative forced choice tasks (2AFC) were used to investigate burst period modulation's role in intensity discernibility. Magnitude estimation tasks were used to determine any interactions in the gradation between the frequency and intensity percepts.Main results.The 2AFC revealed that burst periods can be individually differentiated as a gradable frequency percept in peripheral nerve stimulation. Participants could correctly rate a perceptual scale of intensity and frequency regardless of the value of the second, but the dependence of frequency differentiability on charge rate indicates that frequency was harder to detect with weaker intensity percepts. The same was not observed in intensity differentiability as the length of burst periods did not significantly alter intensity differentiation. These results suggest multidimensional encoding is a promising approach for increasing information throughput in sensory feedback systems if intensity ranges are selected properly.Significance.This study offers valuable insights into haptic feedback through the peripheral nervous system and demonstrates an encoding approach for neural stimulation that may offer enhanced information transfer in virtual reality applications and sensory-enabled prosthetic systems. This multidimensional encoding strategy for sensory feedback may open new avenues for enriched control capabilities.

Factors Affecting Stimulus Duration Threshold for Depth Discrimination of Asynchronous Targets in the Intermediate Distance Range.

Binocular depth discrimination in the near distance range (< 2 m) improves with stimulus duration. However, whether the same response-pattern holds in the intermediate distance range (approximately 2-25 m) remains unknown because the spatial coding mechanisms are thought to be different. We used the two-interval forced choice procedure to measure absolute depth discrimination of paired asynchronous targets (3, 6, or 16 arc min). The paired targets (0.2 degrees) were located over a distance and height range, respectively, of 4.5 to 7.0m and 0.15 to 0.7 m. Experiment 1 estimated duration thresholds for binocular depth discrimination at varying target durations (40-1610 ms), in the presence of a 2 × 6 array of parallel texture-elements spanning 1.5 × 5.83 m on the floor. The texture-elements provided a visible background in the light-tight room (9 × 3 m). Experiment 2 used a similar setup to control for viewing conditions: binocular versus monocular and with versus without texture background. Experiment 3 compared binocular depth discrimination between brief (40, 80, and 125 ms) and continuous texture background presentation. Stimulus duration threshold for depth discrimination decreased with increasing disparity in experiment 1. Experiment 2 revealed depth discrimination performance with texture background was near chance level with monocular viewing. Performance with binocular viewing degraded without texture background. Experiment 3 showed continuous texture background presentation enhances binocular depth discrimination. Absolute depth discrimination improves with target duration, binocular viewing, and texture background. Performance further improved with longer background duration underscoring the role of ground surface representation in spatial coding.

Physical effort precrastination determines preference in an isometric task.

How the brain decides when to invest effort is a central question in neuroscience. When asked to walk a mile to a destination, would you choose a path with a hill at the beginning or the end? The traditional view of effort suggests we should be indifferent-all joules are equal so long as it does not interfere with accomplishing the goal. Yet, when total joules are equal across movement decisions, the brain's sensitivity to the temporal profile of effort investment remains poorly understood. Here, we sought to parse the interaction of time and physical effort by comparing subjective preferences in an isometric arm-pushing task that varied the duration and timing of high and low effort. Subjects were presented with a series of two-alternative forced choices, where they chose the force profile they would rather complete. Subjects preferred earlier physical effort (i.e., to precrastinate) but were idiosyncratic about preference for task timing. A model of subjective utility that includes physical effort costs, task costs, and independent temporal sensitivity factors described subject preferences best. Interestingly, deliberation time and response vigor covary with the same subjective utility model for preference, suggesting a utility that underlies both decision making and motor control. These results suggest physical effort costs are temporally sensitive, with earlier investment of effort preferred to later investment, and that the representation of effort is based on not only the total energy required but also when it is required to invest that energy.NEW & NOTEWORTHY We use a novel paradigm that differentiates physical effort costs, task costs, and time, where subjects choose between isometric arm-pushing tasks. Subjects prefer high physical effort earlier than later. They also decide faster and respond more vigorously the greater their preference. We find a generalizable subjective utility model that includes independent time-sensitivity of physical effort and task costs. Together, we demonstrate that subjective effort includes not only the total effort invested but also its timing.

Signal Detection Theoretic Estimates of the Murine Absolute Visual Threshold Are Independent of Decision Bias.

Decision bias influences estimates of the absolute visual threshold. However, most psychophysical estimates of the murine absolute visual threshold have not taken bias into account. Here we developed a one-alternative forced choice (1AFC) assay to assess the decision bias of mice at the absolute visual threshold via the theory of signal detection and compared our approach with the more conventional high-threshold theoretic approach. In the 1AFC assay, mice of both sexes were trained to signal whether they detected a flash stimulus. We directly measured both hit and false alarm rates, which were used to estimate d' Using the theory of signal detection, we obtained absolute thresholds by interpolating the intensity where d' = 1 from d'-psychometric functions. This gave bias-independent estimates of the absolute visual threshold which ranged over sixfold, averaging ∼1 R* in 1,000 rods (n = 7 mice). To obtain high-threshold theoretic estimates of the absolute visual threshold from the same mice, we estimated threshold intensities from the frequency of seeing curves, corrected for guessing. This gave us thresholds that were strongly correlated with decision bias, ranging over 13-fold and averaged ∼1 R* in 2,500 rods. We conclude that the theory of signal detection uses false alarms to overcome decision bias and narrow the range of threshold estimates in mice, providing a powerful tool for understanding detection behavior near absolute visual threshold.

B - 131 Validation of the California Verbal Learning Test-II-Short Form Forced Choice Paradigm as an Indicator of Performance Validity

Abstract Objective Although the Forced Choice (FC) paradigm of the standard California Verbal Learning Test-Second Edition (CVLT-II) has been extensively validated as an embedded performance validity test (PVT), no studies have validated the CVLT-II Short Form (SF) against a standard battery of external PVTs. Method Participants included 98 veterans (Mage = 69.7 ± 9.0; 86.7% cisgender-male) who completed the CVLT-II-SF FC and the following independent criterion freestanding/embedded PVTS as part of comprehensive outpatient neuropsychological evaluations: the Advanced Clinical Solutions Word Choice Test, Test of Memory Malingering-Trial 1, and Reliable Digit Span from the Wechsler Adult Intelligence Test-Fourth Edition Digit Span subtest. Invalid performance was identified using two different criteria: (1) failing ≥2 PVTs in addition to other clinical indicators of poor engagement, or (2) failing one PVT. Receiver Operator Characteristic (ROC) curves tested the classification accuracy of identifying participants in the invalid group versus those with valid presentations and with or without cognitive impairment. Results Using both criteria, ROC analyses accurately identified invalidity (AUCs = 0.708–0.807) in the total sample, with cut-scores of ≤7 or ≤ 8 on the CVLT-II-SF FC exhibiting adequate specificities (0.900–0.986) and sensitivities of 0.407–0.500. Classification accuracy was acceptable for differentiating the invalid and cognitively intact groups (AUCs = 0.734–0.829) at a cut score of ≤8 (specificities = 0.923–0.958, sensitivities = 0.500–0.704), but was variably acceptable for differentiating the invalid and cognitively impaired groups (AUCs = 0.684–0.794; cut-score of ≤7 with specificities = 0.962–0.978 and sensitivities = 0.229–0.407). Conclusions Our findings support the CVLT-II-SF FC trial as an embedded PVT, particularly when differentiating cognitively intact examinees from those with noncredible presentations.

B - 137 Analyzing Completion Time on a Created Forced Choice Trial of the Hopkins Verbal Learning Test – Revised (HVLT-R) to Measure Engagement in a Mixed Clinical Sample

Abstract Objective We created a forced choice recognition trial (FCR) for the HVLT-R, including recording completion time (FCompT), to evaluate the utility of combining completion time with accuracy scores when using performance validity tests (PVTs). Method Participants included 29 clinically referred patients at a large medical center who completed the HVLT-R in addition to multiple free-standing and embedded PVTs including the TOMM, Word Choice Test (WCT), Reliable Digit Span (RDS), and the Dot Counting Test (DCT) as part of a larger battery of neuropsychological tests in an outpatient setting. Data from the sample (M age = 64.79, SD = 13.86; M education = 15.65, SD = 2.47; 62.1% females) were analyzed using correlation and linear regression. Results The HVLT-R FCR trial correlated with the TOMM-10, r(19) = 0.75, p = &amp;lt;0.001, TOMM trial 1, r(17) = 0.75, p = &amp;lt;0.01, the DCT r(12) = −0.71, p = &amp;lt;0.01, and the FCompT, r(29) = −0.72, p = &amp;lt;0.001. The FCompT was correlated with RDS, r(28) = −0.46, p = 0.03, TOMM-10, r(19) = −0.64, p = &amp;lt;0.01, and TOMM trial 1, r(17) = −0.61, p = &amp;lt;0.01. FCompT significantly predicted FCR accuracy b = −0.72, t(29) = −5.41, p &amp;lt; 0.001. Conclusions The HVLT-R FC and FCompT strongly correlated with free-standing and embedded PVTs. Data demonstrates that a longer completion time predicts poorer performance on FCR. Results demonstrate the value of measuring completion time for specific PVTs, in addition to providing support for the addition of a FCR trial to the HVLT-R.

B - 145 CVLT-3 Forced Choice Recognition Failure Rate in a Mixed Clinical Population

Abstract Objective The CVLT-3 is a measure of verbal learning and memory used extensively in clinical and research settings that contains an embedded performance validity indicator, a forced choice recognition trial (CVLT-3-FCR). The CVLT-2-FCR was modified for the CVLT-3-FCR, replacing abstract with concrete distractor words. To date, no one has reported independent data on failure rates in clinical populations on the CVLT-3-FCR. Method Participants were 373 patients referred for clinical neuropsychological evaluation who completed the CVLT-3 (Standard form) as part of their evaluation. Mean age was 61.20 (SD = 14.30, range = 20–86), mean education was 15.00 years (SD = 2.87, range = 6–21), 53.1% were male, and 97.6% White. Failure was defined as CVLT-3-FCR score ≤ 14. Results 85.5% of our mixed clinical sample had CVLT-3-FCR score of 16/16, and 7.5% had 15/16. Only 7% (N = 26) scored ≤14, most common primary diagnoses being mild neurocognitive disorder (N = 9) and psychiatric (N = 7), while only four had dementia of any etiology. Those who failed tended to be a little older [pass = 60.82 years (SD = 14.44), fail = 66.38 years (SD = 11.28); p = 0.055) and scored lower for CVLT-3 Total Trials 1–5, short- and long-delay free recall, recognition hits, false positives, and discriminability (all p &amp;lt; 0.001). Conclusions Findings indicate CVLT-3-FCR ≤ 14 is extremely rare in a large mixed clinical sample of adults and older adults, even in subsamples for whom lower scores on PVTs have been suggested (e.g., dementia). While passing the CVLT-3-FCR does not in itself confirm adequate test engagement, failure should raise concern and the need for additional PVTs in one’s assessment.

Temporal dynamics of coarticulatory cues to prediction.

The temporal dynamics of the perception of within-word coarticulatory cues remain a subject of ongoing debate in speech perception research. This behavioral gating study sheds light on the unfolding predictive use of anticipatory coarticulation in onset fricatives. Word onset fricatives (/f/ and /s/) were split into four gates (15, 35, 75 and 135 milliseconds). Listeners made a forced choice about the word they were listening to, based on the stimulus gates. The results showed fast predictive use of coarticulatory lip rounding during /s/ word onsets, as early as 15 ms from word onset. For /f/ onsets, coarticulatory backness and height began to be used predictively after 75 ms. These findings indicate that onset times of the occurrence and use of coarticulatory cues can be extremely fast and have a time course that differs depending on fricative type.

Beyond balance: The role of the Vestibular system in action recognition

BackgroundAction recognition is a fundamental aspect of human interaction. This process is mediated by the activation of shared sensorimotor representations during action execution and observation. Although complex movements involving balance or head and trunk rotations require vestibular signals for effective execution, their role in the recognition of others' actions is still unknown. ObjectiveTo investigate the causal involvement of the vestibular system in the discrimination of actions performed by others and whether this is influenced by motor familiarity. MethodsIn a single-blind design involving 25 healthy participants, Galvanic Vestibular Stimulation (GVS) was administered during an Action Discrimination Task (ADT), in which videos of actions categorized as vestibular/non-vestibular and familiar/unfamiliar were presented. Following each video, participants were required to identify the climax of the previously viewed action between two image options, using a two-alternative forced choice paradigm. The ADT was performed in active and sham GVS conditions, with left or right anodal montages. Response Times (RTs), Accuracy, and subjective motor familiarity were recorded for each action category. ResultsIn sham GVS condition, an overall familiarity effect was observed, where RTs for familiar actions were faster than RTs for unfamiliar ones, regardless of vestibular engagement (p < .001; ηp2 = .80). Conversely, under active GVS, a selective interference of the identification of vestibular familiar actions was observed compared to sham. Specifically, GVS prolonged RTs for recognizing familiar vestibular actions (p = .004, d = .59) while concurrently enhancing visual sensitivity (d’) for the same actions (p = .03, r = .21). ConclusionThese findings demonstrate the contribution of the vestibular system to action recognition. GVS disrupted the sensorimotor representation of vestibular actions and led to increased reliance on an alternative processing system focused on visual analysis of limb positions. This dissociation provides valuable insights for future investigations into the complex relationship between vestibular signals and cognitive processes involved in action identification, essential for developing innovative GVS interventions, particularly for individuals with sensorimotor or vestibular disorders.

Individual differences in the consistency of neural and behavioural responses to speech sounds

There are documented individual differences among adults in the consistency of speech sound processing, both at neural and behavioural levels. Some adults show more consistent neural responses to speech sounds than others, as measured by an event-related potential called the frequency-following response (FFR); similarly, some adults show more consistent behavioural responses to native speech sounds than others, as measured by two-alternative forced choice (2AFC) and visual analog scaling (VAS) tasks. Adults also differ in how successfully they can perceive non-native speech sounds. Interestingly, it remains unclear whether these differences are related within individuals. In the current study, native English-speaking adults completed native phonetic perception tasks (2AFC and VAS), a non-native (German) phonetic perception task, and an FFR recording session. From these tasks, we derived measures of the consistency of participants’ neural and behavioural responses to native speech as well as their non-native perception ability. We then examined the relationships among individual differences in these measures. Analysis of the behavioural measures revealed that more consistent responses to native sounds predicted more successful perception of unfamiliar German sounds. Analysis of neural and behavioural data did not reveal clear relationships between FFR consistency and our phonetic perception measures. This multimodal work furthers our understanding of individual differences in speech processing among adults, and may eventually lead to individualized approaches for enhancing non-native language acquisition in adulthood.

‘The mirror of the soul?’ Inferring sadness in the eyes

The eyes are widely regarded as the mirror of the soul, providing reliable nonverbal information about drives, feelings, and intentions of others. However, it is unclear how accurate emotion recognition is when only the eyes are visible and whether inferring of emotions is altered across healthy adulthood. To fill this gap, the present piece of research was directed at comparing the ability to infer basic emotions in two groups of typically developing females that differed in age. We set a focus on females seeking group homogeneity. In a face-to-face study, in a two-alternative forced choice paradigm (2AFC), participants had to indicate emotions for faces covered by masks. The outcome reveals that although the recognition pattern is similar in both groups, inferring sadness in the eyes substantially improves with age. Inference of sadness is not only more accurate and less variable in older participants, but also positively correlates with age from early through mid-adulthood. Moreover, reading sadness (and anger) is more challenging in the eyes of male posers. A possible impact of poser gender and cultural background, both in expressing and inferring sadness in the eyes, is highlighted.