Gap Discrimination Research Articles

Complex trade-offs in a dual-target visual search task are indexed by lateralised ERP components

In everyday tasks, the choices we make incorporate complex trade-offs between conflicting factors that affect how we will achieve our goals. Previous experimental research has used dual-target visual search to determine how people flexibly adjust their behaviour and make choices that optimise their decisions. In this experiment, we leveraged a visual search task that incorporates complex trade-offs, and electroencephalography (EEG), to understand how neural mechanisms of selective attention contribute to choice behaviour in these tasks. On each trial, participants could choose to respond to the gap location on either of two possible targets. Each target was colour coded such that colour indicated which of the two had the easier gap discrimination. Orthogonally, we manipulated the set size of coloured distractors to modulate how efficiently each target could be found. As a result, optimised task performance required participants to trade-off conflicts between the ease of finding a target given the current set size, and the ease of making its associated gap discrimination. Our results confirm that participants are able to flexibly adjust their behaviour, and trade-off these two factors to maintain their response speed and accuracy. Additionally, the N2pc and SPCN components elicited by search displays could reliably predict the choice that participants would ultimately make on a given trial. These results suggest that initial attentional processes may help to determine the choice participants make, highlighting the central role that attention may play in optimising performance on complex tasks.

Auditory Temporal Discrimination from the Perspective of Gap

Abstract Gap detection refers to the perceptual ability to detect brief silences in auditory stimuli. This study investigates temporal discrimination in relation to the perception and processing of gaps. Experiments were conducted to measure gap discrimination thresholds using markers of different frequencies. The results reveal that the threshold for gap discrimination varies depending on the frequency separation between the leading and trailing markers. Notably, when the markers have identical frequencies, the threshold increases monotonically up to the study limit of 100 ms, with a slope that deviates from Weber’s law. To better comprehend these findings, a previously proposed neural model of gap detection was expanded to account for discrimination. This model shows good compatibility with the experimental results and is able to unify gap detection with temporal discrimination. The model also provides a possible mechanism for the pacemaker in the internal clock hypothesis.

The Significant Factors Influencing Individual’s Perceptions of Pay Gap

Various studies have shown that there exist gender-related inequalities in employee compensation. Yet, individuals may also develop affective and behavioural outcomes based on their perceptions of whether they experience such inequalities or observe such inequalities (dis) favouring others. This paper seeks to examine the different factors that could be linked to individuals' pay gap perceptions. The study aims to analyze how demographic factors can significantly impact individuals' perceptions of the pay gap by looking at the relationship between the two variables, where the demographic factors are the independent variable and the perceptions become the dependent variable. The survey was made by adapting from two previous studies about gender discrimination. Hypotheses were tested by utilizing a hierarchical linear regression through SPSS with a sample size of 217 participants from 3 continents: Europe, Asia, and America. Findings showed that gender, age, marital status and equity sensitivity are significantly linked to pay gap perceptions. Specifically, the study found that individuals reported higher pay gap discrimination against their own gender and benefitting the opposite gender. The limitations of this study include its small sample size and cross-sectional design, which affects the generalizability of its findings. This research contributes to the literature on employee compensation, as it features some factors that are linked to individual pay gap perceptions. Theoretically, the paper suggests that self-serving bias and gender role theories potentially influence individuals’ wage and justice perceptions. The paper also provides insights that could help HR professionals design better compensation and communication practices.

Influence of atrial cycle length and site of origin on the peak frequency of bipolar electrograms to discriminate isthmus conduction in atrial scar

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Abbott Background Peak frequency (PF) of conventional bipolar electrograms is a novel parameter which may distinguish between near-field (NF) and far-field (FF) signals. However, the influence of activation rate and the direction of the activation front on it is unknown. Purpose 1. To study the influence of atrial cycle length and wavefront origin on PF to detect residual conduction in a well-defined model of narrow isthmus of conduction such as subacute pulmonary vein (PV) reconnection following atrial fibrillation ablation. 2. To compare this influence with that found for Bipolar voltage (BiV). Methods Baseline maps were acquired in redo PV isolation (PVI) procedures with a 16-pole grid catheter (HD-Grid) during low rate sinus rhythm (SR), low rate coronary sinus pacing at 500 ms cycle length (CSLR) and high rate coronary sinus pacing at 300 ms cycle length (CSHR). PFs were retrospectively computed. PVI sites requiring ≤3 radiofrequency applications were included, with EGMʼs ≤1cm from the PVI site classified as GAP (vs >1cm, No-GAP). Results 28 GAPs were found in 12 of 14 consecutive patients in the study. 3976 EGMʼs (1547 GAP vs 2429 No-GAP) were analyzed. In both GAP and No-GAP, PF was similar in SR vs CSLR (GAP: 363±132 Hz -SR vs 345±135 Hz -CSLR, P=NS ; No-GAP: 196±110 Hz -SR vs 181±116 Hz -CSLR, P=NS). PF was slightly higher for CSLR vs CSHR. (GAP: 345±135 Hz -CSLR vs 317±154 Hz -CSHR, P<0.001; No-GAP 181±116 mV -CSLR vs 162±129 mV -CSHR, P<0.01). (Panel A). BiV was significantly higher in SR vs CS pacing but similar between CSLR and CSHR (GAP: 1.86±2.11 mV -SR vs 0.87±1.19 mV -CSLR vs 0.74±0.92 mV -CSHR, P= NS, No-GAP: 0.62±1.22 mV -SR vs 0.33±0.68 mV - CSLR vs 0.27±0.48 mV - CSHR, P=NS. (Panel B). ROC GAP discrimination for PF was similar between SR and CSLR (AUCʼs: 0.86-SR, 0.84-CSLR) and slightly lower for CSHR (AUC: 0.81) with optimal cutoffs of 260, 240 and 220 Hz, respectively. ROC GAP discrimination for BiV was lower vs PF in all rhythm modes (AUCʼs: 0.77-SR, 0.74-CSLR, 0.75-CSHR), with optimal cutoffs of 0.3, 0.2 and 0.15 mV, respectively. Conclusion ROC gap discrimination was significantly higher for all rhythm modes with PF vs BiV. PF showed slightly decreasing cutoff values for SR, CSLR and CSHR respectively, whereas BiV showed a greater relative decrease in cutoffs for SR, CSLR and CSHR.

Validation of the peak frequency of bipolar electrograms for detection of residual conduction in atrial scar tissue

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Abbott Background Activation and voltage (Bi-V) maps (Panel A) based on conventional bipolar electrograms (EGMs) are influenced by both near-field (NF) and far-field (FF) EGM components. This represents a limitation in the accurate detection of residual conduction within regions of scar. Peak frequency (PF) EGM analysis may better distinguish NF from FF activation vs conventional detection methods. (Panels B & C) Purpose 1. To validate the use of PF to detect residual conduction in a well-defined model of narrow isthmus of conduction such as subacute pulmonary vein (PV) reconnection following atrial fibrillation ablation. 2. To compare discrimination value of PF and conventional Bi-V to detect such isthmuses. Methods Bi-V and activation maps were acquired during redo PV isolation (PVI) procedures using a rectangular 16-pole catheter (HD-Grid). LA-PV conduction was assessed during coronary sinus (CS) pacing (500ms cycle length). Any conduction gap (GAP) site at which PVI was established using ≤3 focal radiofrequency applications was analyzed. (Panel A) EGMʼs ≤1cm from the site of PVI were classified as GAP (vs EGMʼs ≥1cm - No-Gap). (Panel B) Results 28 GAPs were found in 12 of 14 consecutive patients in the study. 3,976 EGMʼs (1,547 GAP vs 2,429 No-GAP) were analyzed. GAP regions showed significantly higher PF than No-GAP regions (345 ±135 vs 181±116 Hz, P<0.0001) (Panel E). GAP regions also showed significantly higher BiV than No-GAP regions (1.86±2.11 mV vs 0.62±1.22 mV, P<0.0001) (Panel D). ROC curves for GAP vs No-GAP discrimination were better for PF (AUC 0.84) than for Bi-V (AUC 0.74) with optimal cutoffs of 240 Hz and 0.2 mV, respectively. (Panel F) Conclusion PF better detects residual conduction within an atrial scar region than conventional Bi-V. The PF cutoff value for gap discrimination in the PV antra is 240 Hz.

THE GENDER PAY GAP: A CASE STUDY OF LOWER KURRAM AGENCY- KHYBER PAKHTUNKHWA

This paper shows the issues concerning to the gender wage gap in district kurram, Parachinar. This study examined the features that affect gender wage pay gap discrimination in the non-governmental private sector. In this in-depth correlation, structured primary data has been collected from various sample respondents having the perception of both males and females of entirely classes existing upon higher, lower and middle category of workforces. The data of the existing study have been poised from diversify channel namely the financial intermediaries (banks), academia, non-governmental organization and health sector in district kurram, Parachinar. For the estimation of wages model, we empirically employed Mincer Earning Function (MEF). The study carries out an embracing descriptive result of the given data. Keeping in view, the empirical estimation of the dependent variable has been analyzed through Ordinary Least Square (OLS) method. The finalized outcomes of the OLS model indicates that the dependent variable highlights the monthly wages of a selected sample respondents while explanatory variables comprise on gender, education, experience, occupation. Almost all variables are found to be significant with an excepted sign. Keywords: Earning function, Gender disparity, Discrimination, Labor market

Selective Interruption of Auditory Interhemispheric Cross Talk Impairs Discrimination Learning of Frequency-Modulated Tone Direction But Not Gap Detection and Discrimination.

Functional hemispheric lateralization is a basic principle of brain organization. In the auditory domain, the right auditory cortex (AC) determines the pitch direction of continuous auditory stimuli whereas the left AC discriminates gaps in these stimuli. The involved functional interactions between the two sides, mediated by commissural connections, are poorly understood. Here, we selectively disrupted the interhemispheric cross talk from the left to the right primary AC and vice versa using chromophore-targeted laser-induced apoptosis of the respective projection neurons, which make up 6-17% of all AC neurons in Layers III, V, and VI. Following photolysis, male gerbils were trained in a first experimental set to discriminate between rising and falling frequency-modulated (FM) tone sweeps. The acquisition of the task was significantly delayed in lesioned animals of either lesion direction. However, the final discrimination performance and hit rate was lowest for animals with left-side lesioned commissural neurons, demonstrating that also information from the left AC is relevant for FM direction learning. Photolysis after successful learning did not affect the retrieval of the learned task, indicating that the disruption during learning was not because of a general functional impairment. In a second experimental set, the gerbil's ability to detect and discriminate small silent gaps of varying length within FM sweeps was tested. This ability was also preserved after interhemispheric disruption. Taken together, interhemispheric communication between the left and right AC is important for the acquisition of FM tone direction learning but not for its retrieval and for gap detection and gap duration discrimination.SIGNIFICANCE STATEMENT Hemispheric lateralization of neuronal functions such as speech and music processing in humans are common throughout the brain; however, the involved interhemispheric interactions are ill-defined. Here, we show that the selective photolytic disruption of auditory cortical commissural connections in rodents impairs the acquisition but not retrieval of a frequency-modulated tone direction discrimination task. The final discrimination performance and hit rate was lowest for animals with lesioned left-to-right-side projections; thus, although right auditory cortex is dominant, left auditory cortex is also relevant for learning this task. The detection and discrimination of small gaps within the tone sweeps remain intact, suggesting a pathway for the processing of these temporal structures, which could be independent from the lesioned interhemispheric cross talk.

Double Roles of Married Working Women in Indonesia: For Better or For Worse

SDGs 2030 have at least two goals that strongly converged to gender equality of pay, gender equality, and decent work and economic growth. Marital status argued to have significant contribution in gender inequality of pay and the root of female wage penalty. The argument associated with traditional family division of labour, where men responsible for family breadwinner and women for family caregiver. We examine this argument in Indonesia experiences with additional feature of multiple breadwinner models in the family. Utilizing Indonesian National Labour Force Survey of 2015 of more than 150.000 workers, our twofold regression compatible Oaxaca-Blinder decomposition analysis confirmed the existence of statistically significant gender wage gap even when controlling for the human capital investment, family division of labour, institutional instrument and discrimination. Our findings suggest that married women tend to take a double roles than married men, being family breadwinner as well as family caregiver. In that double roles model, wage rate are highest among working women and marriage wage penalty died out. Unfortunately gender wage gap and wage discrimination persisted. While the role of minimum wage as current nominal institutional labour market instrument still trivial, other factors must also be addressed toward gender equality of pay and more efficient labour market.SDGs 2030 have at least two goals that strongly converged to gender equality of pay, gender equality, and decent work and economic growth. Marital status argued to have significant contribution in gender inequality of pay and the root of female wage penalty. The argument associated with traditional family division of labour, where men responsible for family breadwinner and women for family caregiver. We examine this argument in Indonesia experiences with additional feature of multiple breadwinner models in the family. Utilizing Indonesian National Labour Force Survey of 2015 of more than 150.000 workers, our twofold regression compatible Oaxaca-Blinder decomposition analysis confirmed the existence of statistically significant gender wage gap even when controlling for the human capital investment, family division of labour, institutional instrument and discrimination. Our findings suggest that married women tend to take a double roles than married men, being family breadwinner as well as family caregiver. In that double roles model, wage rate are highest among working women and marriage wage penalty died out. Unfortunately gender wage gap and wage discrimination persisted. While the role of minimum wage as current nominal institutional labour market instrument still trivial, other factors must also be addressed toward gender equality of pay and more efficient labour market.

The Gender Wage Gap within the Agricultural Sector: A Case from South Lebanon

Agriculture is considered an important energizer of a country’s economic growth and poverty alleviation efforts. However, this sector is underperforming especially in developing countries in part because women, who are often a crucial human resource in agriculture and the rural economy, face difficulties that reduce their productivity and their effective involvement. This paper sheds light on the gender pay gap in Lebanon, in general, and the agriculture sector of South Lebanon, in particular. Exploratory quantitative analysis is applied using a convenient sample of 385 agricultural employees chosen from the Lebanese agricultural institutions in South Lebanon. The paper objectives include the assessment of the wage gap in the agricultural sector in South Lebanon, analyzing opinions towards the wage gap in South Lebanon, quantifying the impact of the gender pay gap on women, identifying the causes that lead to the existence of a wage gap, and the exploration of the existence of wage gap discrimination. Findings showed that the wage gap in the agricultural sector is affected by experience, age, family responsibilities, and physical ability which is a vital factor affecting the wage difference, while the nationality and the educational level had no effect on wage gap. Also, the study showed that there is a 40% wage gap, where the numbers of male and female employees with their average hourly wages were considered which is a significant difference in pay. The outcomes are important for NGOs, policy makers and rural authorities to plan innovatively and capitalize on the untapped female workforce in the agricultural sector of the country.

The Effect of Confidence Rating on a Primary Visual Task.

The current study explored the influence of confidence rating on visual acuity. We used brief exposures of the Landolt gap discrimination task, probing the primary visual ability to detect contrast. During 200 practice trials, participants in the Confidence Rating group rated their response-confidence in each trial. A second (Time Delay) group received a short break at the end of each trial, equivalent to the average rating response time of the Confidence Rating group. The third (Standard Task) group performed the Landolt gap task in its original form. During practice, the Confidence Rating group developed an efficient monitoring ability indicated by a significant correlation between accuracy and confidence rating and a moderate calibration index score. Following practice, all groups performed 400 identical test trials of the standard Landolt gap task. In the test trials, the Confidence Rating group responded more accurately than the control groups, though it did not differ from them in response time for correct answers. Remarkably, the Confidence Rating group was significantly slower when making errors, compared the control groups. An interaction in learning efficiency occurred: the Confidence Rating group significantly improved its reaction times after the initial practice, as compared to both control groups. The findings demonstrate an effect of confidence rating on the formation of processing and response strategies, which granted participants significant benefits in later performance.

Long Term Cosmetic Application Improves Tactile Discrimination in the Elderly; a New Psychophysical Approach.

Introduction: Tactile sensitivity is impaired in older adults, which contributes to the loss of manual dexterity and mobility function. The reliability of classical psychophysical tests, such as two-point gap discrimination, has been questioned. Here we tested a new method to determine tactile acuity during dynamic touch, which is more functional than static touch. The aim was to validate a method providing a high level of discrimination of tactile acuity in the elderly.Methods: We tested the ability of subjects to evaluate the distance between bands printed on poly-methyl-methacrylate (PMMA) sheets. Pairs of sheets were compared in two groups of participants aged from 60 to 74 years; the test group was required to apply a cosmetic foam with an active ingredient on both their hands twice a day for 1 month, the control group had an identical task but used the same cosmetic foam without any active ingredient. The tests were run in a double-blind, placebo-controlled study.Results: The tactile discrimination threshold decreased by 83 μm after 1 month of cosmetic application in the group using the active ingredient, while it was unchanged in the control group.Discussion: The test presented here provided highly accurate results and should be useful to determine tactile performance. It allows the monitoring of tactile rehabilitation and/or skin treatments used to restore tactile acuity in the elderly.

Discrimination of canopy gaps and non-regenerating openings in old-growth temperate deciduous forests using airborne LiDAR data

The use of LiDAR in the study of gap regimes has seen significant progress in recent years. Researchers have assumed that canopy gaps detected in this manner are ecologically equivalent to gaps sampled in situ by more traditional methods. However, those latter methods usually include canopy gaps only and ignore non-regenerating openings that are produced by causes limiting tree establishment. We developed a predictive model capable of discriminating between canopy gaps and non-regenerating openings using LiDAR-derived data. Selected predictive variables were related to conditions that limit tree establishment such as zones of moisture accumulation and steep slopes or to the resulting vegetation physiognomy. The model was applied to three old-growth maple forests to predict the fractions of canopy openings belonging to these two types. On average, non-regenerating openings represented 19.5% of the total area detected as canopy openings and occupied 1.37% of the sites. Canopy gaps formed 80.5% of the total area in canopy openings and covered 5.71% of sites that were studied. The non-regenerating opening seemed more frequent on thin surficial deposits. The canopy gap fraction was similar among study sites but had lower values than usually reported for temperate deciduous forest.

Portable Automated Rapid Testing (PART) measures for auditory research

This presentation will focus on data collected across the globe on tablet computers using applications available for free download, built-in sound hardware, and calibrated consumer-grade headphones. Tests involve spatial release from speech-on-speech masking, binaural sensitivity, gap discrimination, temporal modulation, spectral modulation, and spectrotemporal modulation. The data will be compared across sites and with data from the published literature. The similarity of the obtained data to the expected values and the consistency across sites will help evaluate the potential of this relatively inexpensive and easily disseminated approach to psychoacoustical data collection. The extent to which valid performance can be obtained is a metric of the possibility that in the future such test methods could be used by researchers without access to a full laboratory, clinicians interested in evaluating auditory function beyond the audiogram, and students as part of their training, as well as many other uses not yet imagined.This presentation will focus on data collected across the globe on tablet computers using applications available for free download, built-in sound hardware, and calibrated consumer-grade headphones. Tests involve spatial release from speech-on-speech masking, binaural sensitivity, gap discrimination, temporal modulation, spectral modulation, and spectrotemporal modulation. The data will be compared across sites and with data from the published literature. The similarity of the obtained data to the expected values and the consistency across sites will help evaluate the potential of this relatively inexpensive and easily disseminated approach to psychoacoustical data collection. The extent to which valid performance can be obtained is a metric of the possibility that in the future such test methods could be used by researchers without access to a full laboratory, clinicians interested in evaluating auditory function beyond the audiogram, and students as part of their training, as well as many other uses not...

Development and validation of Portable Automated Rapid Testing (PART) measures for auditory research.

The current state of consumer-grade electronics means that researchers, clinicians, students, and members of the general public across the globe can create high-quality auditory stimuli using tablet computers, built-in sound hardware, and calibrated consumer-grade headphones. Our laboratories have created a free application that supports this work: PART (Portable Automated Rapid Testing). PART has implemented a range of psychoacoustical tasks including: spatial release from speech-on-speech masking, binaural sensitivity, gap discrimination, temporal modulation, spectral modulation, and spectrotemporal modulation (STM). Here, data from the spatial release and STM tasks are presented. Data were collected across the globe on tablet computers using applications available for free download, built-in sound hardware, and calibrated consumer-grade headphones. Spatial release results were as good or better than those obtained with standard laboratory methods. Spectrotemporal modulation thresholds were obtained rapidly and, for younger normal hearing listeners, were also as good or better than those in the literature. For older hearing impaired listeners, rapid testing resulted in similar thresholds to those reported in the literature. Listeners at five different testing sites produced very similar STM thresholds, despite a variety of testing conditions and calibration routines. Download Spatial Release, PART, and Listen: An Auditory Training Experience for free at https://bgc.ucr.edu/games/.

Auditory processing enhancements in the TS2-neo mouse model of Timothy Syndrome, a rare genetic disorder associated with autism spectrum disorders.

Timothy syndrome (TS) is a rare genetic disorder caused by a single de novo missense mutation to the 8A exon of CACNA1C gene, which codes for the voltage-gated L-type Ca2+ channel (Cav1.2). TS is strongly associated with cardiac arrthytmias, autism spectrum disorders (ASDs), and neurological dysfunction such as language impairments, seizures, and intellectual disability. A genetically engineered knock-in mouse with a heterogeneous TS2 (G406R) mutation in the L-type calcium channel containing a neomycin resistance cassette was developed to study ASD-like behaviors. This mouse model (TS2-neo) provides us with a platform to investigate the role of calcium channel inactivation and calcium signaling related to brain development and ASD. The purpose of the current study was to behaviorally characterize TS2-neo mice by assessing their performance on a wide variety of behavioral paradigms, including replication of findings that support the TS2-neo as a valid platform for studying ASD-like behavior. In addition to examining core social and repetitive anomalies, we sought to focus on basic perceptual processing in the auditory domain. Results indicate that the loss of Cav1.2 inactivation in this mouse model results in deviant social and repetitive behaviors as well as poor sensorimotor learning. Additionally, TS2-neo mice display superior performance on both an embedded tone and silent gap discrimination task for short-duration acoustic stimuli. These findings parallel the low-level auditory enhancements observed within the ASD clinical population. Additionally, structural anomalies were seen for mutant mice in some white matter tracts and in the medial geniculate nucleus (MGN). Co-occurrence of these findings suggests that aberrant MGN morphology may be related to enhanced auditory processing phenotype as seen in ASD.

Effects of Hand Proximity and Movement Direction in Spatial and Temporal Gap Discrimination.

Previous research on the interplay between static manual postures and visual attention revealed enhanced visual selection near the hands (near-hand effect). During active movements there is also superior visual performance when moving toward compared to away from the stimulus (direction effect). The “modulated visual pathways” hypothesis argues that differential involvement of magno- and parvocellular visual processing streams causes the near-hand effect. The key finding supporting this hypothesis is an increase in temporal and a reduction in spatial processing in near-hand space (Gozli et al., 2012). Since this hypothesis has, so far, only been tested with static hand postures, we provide a conceptual replication of Gozli et al.’s (2012) result with moving hands, thus also probing the generality of the direction effect. Participants performed temporal or spatial gap discriminations while their right hand was moving below the display. In contrast to Gozli et al. (2012), temporal gap discrimination was superior at intermediate and not near hand proximity. In spatial gap discrimination, a direction effect without hand proximity effect suggests that pragmatic attentional maps overshadowed temporal/spatial processing biases for far/near-hand space.

Within- and between-frequency gap duration discrimination as a function of the standard duration

It is well known that individuals exhibit worse performance during between-frequency gap detection than during within-frequency gap detection. A similar performance difference is also found between within- and between-frequency gap duration discrimination involving undetectably short standard durations. This is reasonable because such discrimination could be considered to be a variant of gap detection. However, because of the paucity of existing data, it is unclear whether frequency differences affects gap discrimination tasks involving longer standard durations. In this study, we measured within- and between-frequency discrimination thresholds in the presence of various standard durations from 1 to 100 ms. As a result, it was shown that the within-frequency thresholds were significantly lower than the between-frequency thresholds when a standard duration of 1-ms was employed, whereas there were no significant differences between them when the standard duration was >50 ms. This implies that the within- an...

Relating age and hearing loss to monaural, bilateral, and binaural temporal sensitivity.

Older listeners are more likely than younger listeners to have difficulties in making temporal discriminations among auditory stimuli presented to one or both ears. In addition, the performance of older listeners is often observed to be more variable than that of younger listeners. The aim of this work was to relate age and hearing loss to temporal processing ability in a group of younger and older listeners with a range of hearing thresholds. Seventy-eight listeners were tested on a set of three temporal discrimination tasks (monaural gap discrimination, bilateral gap discrimination, and binaural discrimination of interaural differences in time). To examine the role of temporal fine structure in these tasks, four types of brief stimuli were used: tone bursts, broad-frequency chirps with rising or falling frequency contours, and random-phase noise bursts. Between-subject group analyses conducted separately for each task revealed substantial increases in temporal thresholds for the older listeners across all three tasks, regardless of stimulus type, as well as significant correlations among the performance of individual listeners across most combinations of tasks and stimuli. Differences in performance were associated with the stimuli in the monaural and binaural tasks, but not the bilateral task. Temporal fine structure differences among the stimuli had the greatest impact on monaural thresholds. Threshold estimate values across all tasks and stimuli did not show any greater variability for the older listeners as compared to the younger listeners. A linear mixed model applied to the data suggested that age and hearing loss are independent factors responsible for temporal processing ability, thus supporting the increasingly accepted hypothesis that temporal processing can be impaired for older compared to younger listeners with similar hearing and/or amounts of hearing loss.

Assessment of novel binocular colour, motion and contrast tests in glaucoma

The effects of glaucoma on binocular visual sensitivity for the detection of various stimulus attributes are investigated at the fovea and in four paracentral retinal regions. The study employed a number of visual stimuli designed to isolate the processing of various stimulus attributes. We measured absolute contrast detection thresholds and functional contrast sensitivity by using Landolt ring stimuli. This psychophysical Landolt C-based contrast test of detection and gap discrimination allowed us to test parafoveally at 6 ° from fixation and foveally by employing interleaved testing locations. First-order motion perception was examined by using moving stimuli embedded in static luminance contrast noise. Red/green (RG) and yellow/blue (YB) colour thresholds were measured with the Colour Assessment and Diagnosis (CAD) test, which utilises random dynamic luminance contrast noise (± 45 %) to ensure that only colour and not luminance signals are available for target detection. Subjects were normal controls (n = 65) and glaucoma patients with binocular visual field defects (n = 15) classified based on their Humphrey Field Analyzer mean deviation (MD) scores. The impairment of visual function varied depending on the stimulus attribute and location tested. Progression of loss was noted for all tests as the degree of glaucoma increased. For subjects with mild glaucoma (MD -0.01 dB to -6.00 dB) significantly more data points fell outside the normal age-representative range for RG colour thresholds than for any other visual test, followed by motion thresholds. This was particularly the case for the parafoveal data compared with the foveal data. Thus, a multifaceted measure of binocular visual performance, incorporating RG colour and motion test at multiple locations, might provide a better index for comparison with quality of life measures in glaucoma.

Discrimination of Brief Gaps Marked by Two Stimuli: Effects of Sound Length, Repetition, and Rhythmic Grouping

We examined the effects of sound marker length, marker repetition, and rhythmic grouping on auditory gap discrimination. The discrimination ofthe duration of a gap between two markers was impaired by lengthening these markers (from 150 to 262.5 ms). Discrimination was impaired by lengthening the preceding marker relative to lengthening the following marker, while the impairment was not increased when both markers were lengthened compared with when only the preceding marker was lengthened. This indicates that the level of discrimination is not decided by a simple summation of the effects of the preceding and of the following marker's length. Moreover, discrimination of a gap between a short (S) and a long (L) marker and of a gap between a long and a short marker was improved by repeating the presentation of these gaps (ie by repeating the markers alternately as SLSLSL...): both types of discrimination led to near identical performance. Finally, under the repetition condition each type of discrimination was not related to the tendency for each individual to perceive the stimulus sequences as segmented into rhythmic chunks of a short tone followed by a long tone (as [SL][SL][SL]...), or those of a long tone followed by a short tone (as S][LS][LS][L...).