Advancing textural heterogeneity: Effect of manipulating multi-component model foods on the perception of textural complexity.

The aim of this study was to identify the individual and interacting effects of varying the mechanical properties of two inserts (к-carrageenan beads; 1, 2 and 4% w/w and/or agar-based disks; 0.3, 1.2 and 3% w/w) in pectin-based gels on the perception of textural complexity. A full factorial design was utilised, 16 samples were characterised with sensory and instrumental tests. Rate-All-That-Apply (RATA) was performed by 50 untrained participants. RATA selection frequency provided different information to attribute intensity regarding the detection of low yield stress inserts. In the two-component samples, the perception of textural complexity (n = 89) increased with insert yield stress for both к-carrageenan beads and agar disks. However, with the addition of medium and high yield stress к-carrageenan beads to three-component samples, the increases in perceived textural complexity caused by increased agar yield stress were eliminated. The definition of textural complexity, the number and intensity of texture sensations, as well as their interactions and contrasts, was in line with the results, and the hypothesis that not only mechanical properties but also the interaction of components play a key role in the perception of textural complexity.

Can binaural beats facilitate autonomic recovery following exposure to an acute stressor?

BACKGROUND AND PURPOSE: Binaural beats are seen as a new type of 'digital-drug'. The aim of this study was to determine if binaural beats could facilitate physiological recovery from a mental stressor. MATERIALS AND METHODS: 92 adults were exposed five times each to a 2-min mental stressor and a subsequent 4-min rest period containing silence or 1-of-4 examples of binaural beats (2, 5, 10, and 24 Hz). Physiological recovery across the five rest periods, as measured using skin conductance, heart rate, and breathing, were compared using one-way analysis of variance. RESULTS: Binaural beats were linked to enhanced physiological recovery relative to silence. However, the expected pattern of results whereby lower frequency binaural beats would be associated with greater physiological recovery, was not observed. CONCLUSION: Our findings do not support a relationship between binaural beats and systematic changes in emotional states as measured physiologically. On the basis of our results the acute administration of binaural beats in primary care to lower sympathetic arousal cannot yet be considered an evidence-based practice.

The use of freeze-dried retronasal stimuli to assess olfactory function.

OBJECTIVES: To evaluate a test of olfactory perception that uses freeze-dried stimuli developed to rapidly release aromas capable of migrating to the olfactory mucosa retronasally. DESIGN: Validation study. SETTING: Psychology and Chemistry Departments. PARTICIPANTS: First, 15 participants provided data for psychometric functions. Second, 70 participants made perceptual judgments of retronasal stimuli. Inclusion criterion included informed consent and a satisfactory Nasal Obstruction Symptom Evaluation result. MAIN OUTCOME MEASURES: First, psychometric functions were generated for two types of freeze-dried stimuli (coffee and orange) using the Single-Interval Adjustment Matrix method. Second, participants provided ratings of pleasantness, intensity, and familiarity and performed a standardised identification test using seven retronasally presented aromas alongside the previously validated Sniffin' Sticks orthonasal olfactory test. RESULTS: Psychometric functions indicated a dose-response relationship between aroma concentration and probability of detection. Test-retest reliability of the retronasal stimuli was acceptable (r70  = 0.72, P < 0.001), and identification scores were not dependent on testing method (ie, retronasal vs Sniffin' Sticks). Stimuli delivered using the Sniffin' Sticks test were rated more pleasant than their retronasal counterparts. CONCLUSIONS: Freeze-dried retronasal stimuli offer an easy-to-use and rapid means to test olfaction function and are arguably well suited for clinical practice, but require further development and trialing prior to the adoption in the clinical context.

Electrophysiological indices of amplitude modulated sounds and sensitivity to noise.

Annoyance to unwanted sound differs across individuals, though why noise sensitive individuals are more reactive to noise while others are more resilient remains unanswered. The Information Processing Hypothesis posits that noise sensitive individuals are vulnerable to higher-order auditory processing deficits. The aim of this study was to test the veracity of this hypothesis by documenting differences in pre-attentive auditory evoked potentials (ERP) between high noise sensitive and low noise sensitive individuals. Participants provided annoyance measures for three amplitude-modulated sounds, and were exposed to the sounds while undergoing electroencephalogram recording. Results indicated that annoyance increased with modulation, and that modulation affected both N1 and P2 components. At the group level, highly noise sensitive individuals exhibited significantly greater annoyance to a low-frequency tone, alongside significantly higher P2 amplitude, than individuals reporting low levels of noise sensitivity. Overall, the results partially supported the Information Processing Hypothesis of noise sensitivity, but also suggest that acoustic features may be more important than hitherto argued.

A multivariate assessment of the rapidly changing procedure with McDowell's Evolutionary Theory of Behavior Dynamics.

A multivariate analysis is concerned with more than one dependent variable simultaneously. Models that generate event records have a privileged status in a multivariate analysis. From a model that generates event records, we may compute predictions for any dependent variable associated with those event records. However, because of the generality that is afforded to us by these kinds of models, we must carefully consider the selection of dependent variables. Thus, we present a conditional compromise heuristic for the selection of dependent variables from a large group of variables. The heuristic is applied to McDowell's Evolutionary Theory of Behavior Dynamics (ETBD) for fitting to a concurrent variable-interval schedule in-transition dataset. From the parameters obtained from fitting ETBD, we generated predictions for a wide range of dependent variables. Overall, we found that our ETBD implementation accounted well for various flavors of the log response ratio, but had difficulty accounting for the overall response rates and cumulative reinforcer effects. Based on these results, we argue that the predictions of our ETBD implementation could be improved by decreasing the base response probabilities, either by increasing the response latencies or by decreasing the sizes of the operant classes.

Performance on the rapidly changing procedure, according to an associative learner.

From a model that generates event records, we may generate predictions for any dependent variable computable from those event records. In the present paper, we examined an implementation of Shimp's (1978) Associative Learner for two-alternative concurrent variable-interval variable-interval schedules in transition. In general, our Associative Learner implementation had difficulty accounting for the inter-response times as a function of the reinforcer ratio, the general frequency of inter-response times, the acquisition of consecutive reinforcers from the same alternative, and the response rates to the not-just-reinforced alternative after a reinforcer. An extended Associative Learner implementation was designed with provisions for increasing responding to the just-reinforced alternative after a reinforcer and organising bout-like responses. The extended implementation rectified many of the weaknesses of the base implementation.

The natural mathematics of behavior analysis.

Models that generate event records have very general scope regarding the dimensions of the target behavior that we measure. From a set of predicted event records, we can generate predictions for any dependent variable that we could compute from the event records of our subjects. In this sense, models that generate event records permit us a freely multivariate analysis. To explore this proposition, we conducted a multivariate examination of Catania's Operant Reserve on single VI schedules in transition using a Markov Chain Monte Carlo scheme for Approximate Bayesian Computation. Although we found systematic deviations between our implementation of Catania's Operant Reserve and our observed data (e.g., mismatches in the shape of the interresponse time distributions), the general approach that we have demonstrated represents an avenue for modelling behavior that transcends the typical constraints of algebraic models.

Evaluating persistence of shape information using a matching protocol.

Many laboratories have studied persistence of shape information, the goal being to better understand how the visual system mediates recognition of objects. Most have asked for recognition of known shapes, e.g., letters of the alphabet, or recall from an array. Recognition of known shapes requires access to long-term memory, so it is not possible to know whether the experiment is assessing short-term encoding and working memory mechanisms, or has encountered limitations on retrieval from memory stores. Here we have used an inventory of unknown shapes, wherein a string of discrete dots forms the boundary of each shape. Each was displayed as a target only once to a given respondent, with recognition being tested using a matching task. Analysis based on signal detection theory was used to provide an unbiased estimate of the probability of correct decisions about whether comparison shapes matched target shapes. Four experiments were conducted, which found the following: a) Shapes were identified with a high probability of being correct with dot densities ranging from 20% to 4%. Performance dropped only about 10% across this density range. b) Shape identification levels remained very high with up to 500 milliseconds of target and comparison shape separation. c) With one-at-a-time display of target dots, varying the total time for a given display, the proportion of correct decisions dropped only about 10% even with a total display time of 500 milliseconds. d) With display of two complementary target subsets, also varying the total time of each display, there was a dramatic decline of proportion correct that reached chance levels by 500 milliseconds. The greater rate of decline for the two-pulse condition may be due to a mechanism that registers when the number of dots is sufficient to create a shape summary. Once a summary is produced, the temporal window that allows shape information to be added may be more limited.

Visual encoding of partial unknown shape boundaries.

Prior research has found that known shapes and letters can be recognized from a sparse sampling of dots that mark locations on their boundaries. Further, unknown shapes that are displayed only once can be identified by a matching protocol, and here also, above-chance performance requires very few boundary markers. The present work examines whether partial boundaries can be identified under similar low-information conditions. Several experiments were conducted that used a match-recognition task, with initial display of a target shape followed quickly by a comparison shape. The comparison shape was either derived from the target shape or was based on a different shape, and the respondent was asked for a matching judgment, i.e., did it "match" the target shape. Stimulus treatments included establishing how density affected the probability of a correct decision, followed by assessment of how much positioning of boundary dots affected this probability. Results indicate that correct judgments were possible when partial boundaries were displayed with a sparse sampling of dots. We argue for a process that quickly registers the locations of boundary markers and distills that information into a shape summary that can be used to identify the shape even when only a portion of the boundary is represented.

Atypical brain responses to auditory spatial cues in adults with autism spectrum disorder.

The auditory processing atypicalities experienced by many individuals on the autism spectrum disorder might be understood in terms of difficulties parsing the sound energy arriving at the ears into discrete auditory 'objects'. Here, we asked whether autistic adults are able to make use of two important spatial cues to auditory object formation - the relative timing and amplitude of sound energy at the left and right ears. Using electroencephalography, we measured the brain responses of 15 autistic adults and 15 age- and verbal-IQ-matched control participants as they listened to dichotic pitch stimuli - white noise stimuli in which interaural timing or amplitude differences applied to a narrow frequency band of noise typically lead to the perception of a pitch sound that is spatially segregated from the noise. Responses were contrasted with those to stimuli in which timing and amplitude cues were removed. Consistent with our previous studies, autistic adults failed to show a significant object-related negativity (ORN) for timing-based pitch, although their ORN was not significantly smaller than that of the control group. Autistic participants did show an ORN to amplitude cues, indicating that they do not experience a general impairment in auditory object formation. However, their P400 response - thought to indicate the later attention-dependent aspects of auditory object formation - was missing. These findings provide further evidence of atypical auditory object processing in autism with potential implications for understanding the perceptual and communication difficulties associated with the condition.

See food diet? Cultural differences in estimating fullness and intake as a function of plate size.

Previous research has suggested that manipulations of plate size can have a direct impact on perception of food intake, measured by estimated fullness and intake. The present study, involving 570 individuals across Canada, China, Korea, and New Zealand, is the first empirical study to investigate cultural influences on perception of food portion as a function of plate size. The respondents viewed photographs of ten culturally diverse dishes presented on large (27 cm) and small (23 cm) plates, and then rated their estimated usual intake and expected fullness after consuming the dish, using 100-point visual analog scales. The data were analysed with a mixed-model ANCOVA controlling for individual BMI, liking and familiarity of the presented food. The results showed clear cultural differences: (1) manipulations of the plate size had no effect on the expected fullness or the estimated intake of the Chinese and Korean respondents, as opposed to significant effects in Canadians and New Zealanders (p < 0.05); (2) Canadian (88.91 ± 0.42) and New Zealanders (90.37 ± 0.41) reported significantly higher estimated intake ratings than Chinese (80.80 ± 0.38) or Korean (81.69 ± 0.44; p < 0.05), notwithstanding the estimated fullness ratings from the Western respondents were comparable or even higher than those from the Asian respondents. Overall, these findings, from a cultural perspective, support the notion that estimation of fullness and intake are learned through dining experiences, and highlight the importance of considering eating environments and contexts when assessing individual behaviours relating to food intake.

Pre-asymptotic response rates as a function of the delay-of-reinforcement gradient summation for Catania's Operant Reserve: A reply to Berg & McDowell (2011).

Catania's Operant Reserve (COR; Catania, 2005) is a computational model of operant behaviour. In COR, responding depletes the reserve while reinforcement replenishes the reserve. The replenishment to the reserve depends on the location of responses within the most recent inter-reinforcement interval. The rule that maps replenishment to the responses within an inter-reinforcement interval is given by a delay-of-reinforcement gradient (DOR). Previous research (Berg and McDowell, 2011) found that non-linear DORs produce sigmoidal response rates on single variable-interval schedules while a linear DOR produces hyperbolic response rates. Berg and McDowell took these sigmoidal response rates as evidence against the viability of COR for modelling variable-interval performance. However, Berg and McDowell did not consider the effect of the slope of each DOR. The present conjecture is that the response rates from COR can be made hyperbolic by manipulating the area under the DOR. Our results show that the manipulation of the area under the DOR allows COR to produce hyperbolic response rates regardless of the parametric form of the DOR. Hence, if COR is to be used to model single variable-interval performance, the reinforcement effect over time should be taken into consideration through the manipulation of the area under the DOR.

Methods for Fitting Olfactory Psychometric Functions: A Case Study Comparing Psychometric Functions for Individuals with a "Sensitive" or "Insensitive" Genotype for ß-Ionone.

In psychophysics, the detection of sensory signals can be depicted by a psychometric function (PF)-a sigmoid function determined by the intercept (i.e., threshold) and the slope (i.e., the rate of increase of detection probability). Fitting psychometric functions is, however, unpopular in chemosensory research, particularly in olfaction. Most olfactory studies adopt ad hoc methods involving a fixed-performance criterion, which result only in a threshold estimate rather than a complete detection profile. This study illustrates the method selection process for fitting olfactory PFs, using a unique odorant-ß-ionone-as an exemplar. This particular odorant has a bimodal threshold distribution across the population, which is known to associate with individuals' genotypes for rs6591536 . The characteristics of ß-ionone enabled us to use a receiver operating characteristic analysis to assess the different odor threshold estimation methods. The results showed that the available methods based on PFs discriminated between individuals of different genotypes with greater accuracy than the ad hoc method. By fitting PFs to the separate genotypic groups, we also made the first observation of the relationship between genotypic variation and the slope parameter of olfactory PFs. The genetically identified ß-ionone "sensitive" group ( s = 1.102-1.883) was shown to have significantly shallower PFs than the ß-ionone "insensitive" group ( s = 0.542-0.724). The slope difference may indicate potential discrepancies in the combinatorial coding scheme of odors between these 2 genotype groups, inviting future research to identify the physiological basis.

Is there a generalized sweetness sensitivity for an individual? A psychophysical investigation of inter-individual differences in detectability and discriminability for sucrose and fructose.

Despite the historical interest in the taste of sweetness, a seemingly fundamental question has not been properly addressed. That is, whether an individual's sensitivity can be generalized across different sugars. An answer to this question has a close relevance to illuminating the sensory physiology of the gustatory system, as well as to practical research of sucrose substitution. A cross-disciplinary review highlights two weak links with the psychophysical methods that have been employed in the literature. The present paper describes an empirical investigation of inter-individual differences in detectability and discriminability for two types of common sugars - sucrose and fructose, using psychometric functions (PF) and a controlled sensory discrimination test. The study found six of the 12 judges had significantly different thresholds for sucrose and fructose (p<0.05), with no consistent pattern in the direction of differences. This observation challenges the conventional belief that people hold the same perception of relative difference in sweetness across substances. For seven judges, the individually-fitted PFs exhibited different shapes for the tested sugars, implying the detection processing might be substance-specific. Also, inter-individual differences were observed in the controlled discrimination task for sucrose and fructose at a supra-threshold level. These findings are discussed in relation to their theoretical, practical and methodological values. While this study uses sucrose and fructose as exemplars, the findings may provide important insights into sweetness perception in general.

Electrophysiological approaches to noise sensitivity.

BACKGROUND: Noise sensitivity describes an individual's general reactivity to sound. It is a common trait found in many clinical populations and describes approximately 20% of the general population. Little is known about its underlying mechanisms, however. OBJECTIVES: Here we present findings from three studies designed to expose differences in electrophysiological measures between noise-sensitive and noise-resistant individuals. METHOD: Noise sensitivity was estimated using self-report measures, while electrophysiological indices included both cardiac (heart rate, heart rate variability) and electroencephalographic (event-related potential) measures. All three studies were designed with reference to preexisting theoretical frameworks. RESULTS: Significant differences in heart rate change and heart rate variability indices between noise-sensitive and noise-resistant groups were found. Further, the noise-sensitive group exhibited less sensory gating than the noise-resistant group. CONCLUSIONS: While the findings from all three studies were not definitive in indicating a likely biological mechanism underlying noise sensitivity, they do suggest that electrophysiological investigation of noise sensitivity is viable and has potential to inform clinical research into a relatively understudied symptom.

Exploring the autonomic correlates of personality.

The aim of this study was to investigate the relationship between personality and resting heart rate variability (HRV) indices. Healthy volunteers (n=106) completed a 240-item Big Five personality inventory, the state/Trait Anxiety inventory, and a ten minute electrocardiographic recording. Time and frequency domain estimates of HRV were derived from the cardiac time series and related to the Big Five dimensions of personality, to personality types extracted from a cluster analysis, and to Trait Anxiety. Frequency domain measures of HRV (HRV-HF, LF/HF) were associated with specific dimensions of personality, but significance was not noted for the time domain measure (STD-RR). Furthermore, distressed personality types exhibited significantly greater autonomic imbalance (LF/HF) than other personality types. However, significance was not noted for the time domain measure (STD-RR). These results can be explained with reference to a contemporary model of neurovisceral integration.

Lognormal Lorenz and normal receiver operating characteristic curves as mirror images.

The Lorenz curve for assessing economic inequality depicts the relation between two cumulative distribution functions (CDFs), one for the distribution of incomes or wealth and the other for their first-moment distribution. By contrast, the receiver operating characteristic (ROC) curve for evaluating diagnostic systems depicts the relation between the complements of two CDFs, one for the distribution noise and the other for the distribution of signal plus noise. We demonstrate that the lognormal model of the Lorenz curve, which is often adopted to model the distribution of income and wealth, is a mirror image of the equal-variance normal model of the ROC curve, which is a fundamental model for evaluating diagnostic systems. The relationship between these two models extends the potential application of each. For example, the lognormal Lorenz curve can be used to evaluate diagnostic systems derived from equal-variance normal distributions.

The negative affect hypothesis of noise sensitivity.

Some studies indicate that noise sensitivity is explained by negative affect, a dispositional tendency to negatively evaluate situations and the self. Individuals high in such traits may report a greater sensitivity to other sensory stimuli, such as smell, bright light and pain. However, research investigating the relationship between noise sensitivity and sensitivity to stimuli associated with other sensory modalities has not always supported the notion of a common underlying trait, such as negative affect, driving them. Additionally, other explanations of noise sensitivity based on cognitive processes have existed in the clinical literature for over 50 years. Here, we report on secondary analyses of pre-existing laboratory (n = 74) and epidemiological (n = 1005) data focusing on the relationship between noise sensitivity to and annoyance with a variety of olfactory-related stimuli. In the first study a correlational design examined the relationships between noise sensitivity, noise annoyance, and perceptual ratings of 16 odors. The second study sought differences between mean noise and air pollution annoyance scores across noise sensitivity categories. Results from both analyses failed to support the notion that, by itself, negative affectivity explains sensitivity to noise.

Elucidating the relationship between noise sensitivity and personality.

Sensitivity to unwanted sounds is common in general and clinical populations. Noise sensitivity refers to physiological and psychological internal states of an individual that increase the degree of reactivity to noise in general. The current study investigated the relationship between the Big Five personality dimensions and noise sensitivity using the 240-item NEO Personality Inventory (NEO-PI) and 35-item The Noise-Sensitivity-Questionnaire (NoiSeQ) scales, respectively. Overall, the Big Five accounted for 33% of the variance in noise sensitivity, with the Introversion-Extroversion dimension explaining the most variability. Furthermore, the Big Five personality dimensions (neuroticism, extroversion, openness, agreeableness, and conscientiousness) had an independent effect on noise sensitivity, which were linear. However, additional analyses indicated that the influence of gender and age must be considered when examining the relationship between personality and noise sensitivity. The findings caution against pooling data across genders, not controlling for age, and using personality dimensions in isolation.

Recognition memory zROC slopes for items with correct versus incorrect source decisions discriminate the dual process and unequal variance signal detection models.

We tested the dual process and unequal variance signal detection models by jointly modeling recognition and source confidence ratings. The 2 approaches make unique predictions for the slope of the recognition memory zROC function for items with correct versus incorrect source decisions. The standard bivariate Gaussian version of the unequal variance model predicts little or no slope difference between the source-correct and source-incorrect functions. We also developed a "bounded" version of this model that did not permit below-chance source discrimination in any region of the evidence space. The bounded version predicts that the source-correct function should have a lower slope than the source-incorrect function. A bivariate version of the dual process signal detection model can predict slope differences in either direction, but it must predict a u-shaped source zROC function if the source-correct slope is lower than the source-incorrect slope. Across 4 experiments, results consistently showed that the recognition memory zROC function had a lower slope for items attributed to the correct source than items attributed to the incorrect source, and the source zROC function for words recognized with high confidence was linear. Only the bounded version of the unequal variance model successfully predicted the full pattern of results.