Benefits of multinomial processing tree models with discrete and continuous variables in memory research: an alternative modeling proposal to Juola et al. (2019).

Signal detection theory (SDT) and two-high threshold models (2HT) are often used to analyze accuracy data in recognition memory paradigms. However, when reaction times (RTs) and/or confidence levels (CLs) are also measured, they usually are analyzed separately or not at all as dependent variables (DVs). We propose a new approach to include these variables based on multinomial processing tree models for discrete and continuous variables (MPT-DC) with the aim to compare fits of SDT and 2HT models. Using Juola et al.'s (2019, Memory & Cognition, 47[4], 855-876) data we have found that including CLs and RTs reduces the standard errors of parameter estimates and accounts for interactions among accuracy, CLs, and RTs that classical versions of SDT and 2HT models do not. In addition, according to the simulations, there is an increase in the proportion of correct model selections when relevant DV are included. We highlight the methodological and substantive advantages of MPT-DC in the disentanglement of contributing processes in recognition memory.

Response uncertainty influences response bias in the sustained attention to response task: a signal detection theory perspective.

In the current investigation, we modified the high Go, low No-Go Sustained Attention to Response Task (SART) by replacing the single response on Go trials with a dual response to increase response uncertainty. In three experiments, a total of 80 participants completed either the original SART with no response uncertainty regarding the Go stimuli, or versions of the dual response SART in which response probabilities for the two possible responses to the Go stimuli varied from 0.9-0.1, 0.7-0.3, to 0.5-0.5. This resulted in a scale of increasing response uncertainty based on information theory to the Go stimuli. The probability of No-Go withhold stimuli was kept.11 in all experiments. Using the Signal Detection Theory perspective proposed by Bedi et al. (Psychological Research: 1-10, 2022), we predicted that increasing response uncertainty would result in a conservative response bias shift, noted by decreased errors of commission and slower response times to both Go and No-Go stimuli. These predictions were verified. The errors of commission in the SART may not be a measures of conscious awareness per se, but instead indicative of the level of participant trigger happiness-the willingness to respond quickly.

Linking paranormal and conspiracy beliefs to illusory pattern perception through signal detection theory.

Previous research indicates that irrational beliefs (Paranormal beliefs & conspiracy theory endorsement) are associated with the perception of patterns in noise, but the previous findings do not conclusively describe this relationship. This study aims to disentangle the underlying parameters of this association by applying a signal detection theory approach, thus allowing to distinguish illusory pattern perception (false alarms) from perceptual sensitivity and response tendencies-while also taking base rate information into account. Results from a large sample (N = 723) indicate that paranormal beliefs relate to a more liberal response bias and a lower perceptual sensitivity, and that this relationship is driven by illusory pattern perception. Such a clear pattern could not be observed for conspiracy beliefs, for which the increase in false alarm rates was moderated by the base rate. The associations between irrational beliefs and illusory pattern perception were however less substantial compared to other sources of variance. Implications are discussed.

Incorporating Functional Response Time Effects into a Signal Detection Theory Model.

Signal detection theory (SDT; Tanner & Swets in Psychological Review 61:401-409, 1954) is a dominant modeling framework used for evaluating the accuracy of diagnostic systems that seek to distinguish signal from noise in psychology. Although the use of response time data in psychometric models has increased in recent years, the incorporation of response time data into SDT models remains a relatively underexplored approach to distinguishing signal from noise. Functional response time effects are hypothesized in SDT models, based on findings from other related psychometric models with response time data. In this study, an SDT model is extended to incorporate functional response time effects using smooth functions and to include all sources of variability in SDT model parameters across trials, participants, and items in the experimental data. The extended SDT model with smooth functions is formulated as a generalized linear mixed-effects model and implemented in the gamm4 R package. The extended model is illustrated using recognition memory data to understand how conversational language is remembered. Accuracy of parameter estimates and the importance of modeling variability in detecting the experimental condition effects and functional response time effects are shown in conditions similar to the empirical data set via a simulation study. In addition, the type 1 error rate of the test for a smooth function of response time is evaluated.

Go-stimuli probability influences response bias in the sustained attention to response task: a signal detection theory perspective.

The sustained attention to response task (SART) is a popular measure in the psychology and neuroscience of attention. The underlying psychological cause for errors, in particular errors of commission, in the SART is actively disputed. Some researchers have suggested task-disengagement due to mind-wandering or mindlessness, and others have proposed strategic choices. In this study we explored an alternative perspective based on Signal Detection Theory, in which the high rate of commission errors in the SART reflects simply a shift in response bias (criterion) due to the high prevalence of Go-stimuli. We randomly assigned 406 participants to one of ten Go-stimuli prevalence rates (50%, 64%, 74%, 78%, 82%, 86%, 90%, 94%, 98% and 100%). As Go-stimuli prevalence increased reaction times to both Go and No-Go stimuli decreased, omission errors decreased and commission errors increased. These all were predicted from a hypothesized bias shift, but the findings were not compatible with some alternative theories of SART performance. These findings may have implications for similar tasks.

Model-based signal processing enables bidirectional inferring between local field potential and spikes evoked by noxious stimulation.

BACKGROUND: Recording spontaneous and evoked activities by means of unitary extracellular recordings and local field potential (LFP) are key understanding the mechanisms of neural coding. The LFP is one of the most popular and easy methods to measure the activity of a population of neurons. LFP is also a composite signal known to be difficult to interpret and model. There is a growing need to highlight the relationship between spiking activity and LFP. Here, we hypothesized that LFP could be inferred from spikes under evoked noxious conditions. METHOD: Recording was performed from the medullary dorsal horn (MDH) in deeply anesthetized rats. We detail a process to highlight the C-fiber (nociceptive) evoked activity, by removing the A-fiber evoked activity using a model-based approach. Then, we applied the convolution kernel theory and optimization algorithms to infer the C-fiber LFP from the single cell spikes. Finally, we used a probability density function and an optimization algorithm to infer the spikes distribution from the LFP. RESULTS: We successfully extracted C-fiber LFP in all data recordings. We observed that C-fibers spikes preceded the C-fiber LFP and were rather correlated to the LFP derivative. Finally, we inferred LFP from spikes with excellent correlation coefficient (r = 0.9) and reverse generated the spikes distribution from LFP with good correlation coefficients (r = 0.7) on spikes number. CONCLUSION: We introduced the kernel convolution theory to successfully infer the LFP from spikes, and we demonstrated that we could generate the spikes distribution from the LFP.

Neural measures of working memory in a bilateral change detection task.

The change detection task is a widely used paradigm to examine visual working memory processes. Participants memorize a set of items and then, try to detect changes in the set after a retention period. The negative slow wave (NSW) and contralateral delay activity (CDA) are event-related potentials in the EEG signal that are commonly used in change detection tasks to track working memory load, as both increase with the number of items maintained in working memory (set size). While the CDA was argued to more purely reflect the memory-specific neural activity than the NSW, it also requires a lateralized design and attention shifts prior to memoranda onset, imposing more restrictions on the task than the NSW. The present study proposes a novel change detection task in which both CDA and NSW can be measured at the same time. Memory items were presented bilaterally, but their distribution in the left and right hemifield varied, inducing a target imbalance or "net load." NSW increased with set size, whereas CDA increased with net load. In addition, a multivariate linear classifier was able to decode the set size and net load from the EEG signal. CDA, NSW, and decoding accuracy predicted an individual's working memory capacity. In line with the notion of a bilateral advantage in working memory, accuracy, and CDA data suggest that participants tended to encode items relatively balanced. In sum, this novel change detection task offers a basis to make use of converging neural measures of working memory in a comprehensive paradigm.

Experimental sleep loss, racial bias, and the decision criterion to shoot in the Police Officer's Dilemma task.

Violent behavior, police brutality, and racial discrimination are currently at the forefront of society's attention, and they should be. We investigated whether mild sleep loss-as typical for many adults throughout the work week-could aggravate the socio-emotional-cognitive processes contributing to violence and discrimination. In a sample of 40 healthy young adults, we either experimentally restricted participants' sleep for four nights (6.2 h/night) or let participants obtain normal sleep (7.7 h/night)-and then had them complete the Police Officer's Dilemma Task. In this computerized task, the participant must rapidly decide to shoot or not shoot at White and Black men who either are or are not holding a gun. Results showed significant racial biases, including more and quicker shooting of Black targets compared to White targets. Furthermore, signal detection analyses demonstrated that mild sleep restriction changed participants' decision criterion, increasing the tendency to shoot, even when controlling for psychomotor vigilance, fluid intelligence, and self-reported desirability to behave in a socially acceptable manner. The increased tendency to shoot was also observed in participants who reported believing that they had adapted to the sleep loss. Future experimental research using trained police officers will help establish the generalizability of these laboratory effects. Importantly, sleep loss is modifiable via organization-level changes (e.g., shift scheduling, light entrainment) and individual-level interventions (e.g., sleep hygiene education, incentives for behavioral change), suggesting that if sleep loss is corrected, it could save lives-including Black lives.

Psychophysical scaling reveals a unified theory of visual memory strength.

Almost all models of visual memory implicitly assume that errors in mnemonic representations are linearly related to distance in stimulus space. Here we show that neither memory nor perception are appropriately scaled in stimulus space; instead, they are based on a transformed similarity representation that is nonlinearly related to stimulus space. This result calls into question a foundational assumption of extant models of visual working memory. Once psychophysical similarity is taken into account, aspects of memory that have been thought to demonstrate a fixed working memory capacity of around three or four items and to require fundamentally different representations-across different stimuli, tasks and types of memory-can be parsimoniously explained with a unitary signal detection framework. These results have substantial implications for the study of visual memory and lead to a substantial reinterpretation of the relationship between perception, working memory and long-term memory.

A Basal Ganglia Computational Model to Explain the Paradoxical Sensorial Improvement in the Presence of Huntington's Disease.

The basal ganglia (BG) represent a critical center of the nervous system for sensorial discrimination. Although it is known that Huntington's disease (HD) affects this brain area, it still remains unclear how HD patients achieve paradoxical improvement in sensorial discrimination tasks. This paper presents a computational model of the BG including the main nuclei and the typical firing properties of their neurons. The BG model has been embedded within an auditory signal detection task. We have emulated the effect that the altered levels of dopamine and the degree of HD affectation have in information processing at different layers of the BG, and how these aspects shape transient and steady states differently throughout the selection task. By extracting the independent components of the BG activity at different populations, it is evidenced that early and medium stages of HD affectation may enhance transient activity in the striatum and the substantia nigra pars reticulata. These results represent a possible explanation for the paradoxical improvement that HD patients present in discrimination task performance. Thus, this paper provides a novel understanding on how the fast dynamics of the BG network at different layers interact and enable transient states to emerge throughout the successive neuron populations.

Self-focused attention enhances tactile sensitivity in women at risk from eating disorders.

We examined whether alterations in body perception in EDs extend to the integration of exteroceptive visual and tactile information. Moreover, we investigated the effect of self-focused attention on the ability to correctly detect tactile stimuli. Twenty-seven women reporting low ED symptoms, versus 26 women reporting high ED symptoms, undertook a modified version of the Somatic Signal Detection Task (SSDT), which involved detecting tactile stimuli on the cheek in the presence or absence of a concomitant light. The SSDT was completed while looking at a photograph of one's own face, another female face, and a scrambled face. Heart rate and skin conductance were recorded continuously during the SSDT. Although ED symptoms were not associated with an overall increased tendency to misperceive touch in the presence of a light, High ED participants were differentially affected by self-focused attention. For the High ED group, physiological arousal, and tactile sensitivity (d') were increased when self-focused attention was augmented. For the Low ED group, sensitivity (d') and physiological arousal were higher in the control conditions. We suggest that in those with High ED symptoms, attention to the bodily self may exacerbate a predisposition to focusing on external rather than internal bodily information.

Is auditory awareness negativity confounded by performance?

Research suggests that the electrophysiological correlates of consciousness are similar in hearing as in vision: the auditory awareness negativity (AAN) and the late positivity (LP). However, from a recently proposed signal-detection perspective, these correlates may be confounded by performance, as the strength of the internal responses differs between aware and unaware trials. Here, we tried to apply this signal-detection approach to correct for performance in an auditory discrimination and detection task (N = 28). A large proportion of subjects had to be excluded because even a small response bias distorted the correction. For the remaining subjects, the correction mainly increased noise in the measurement. Furthermore, the signal-detection approach is theoretically problematic because it may isolate post-perceptual processes and eliminate awareness-related activity. Therefore, we conclude that AAN and LP are not confounded by performance and that the contrastive analysis identifies both as correlates of awareness.

The interplay between multisensory integration and perceptual decision making.

Facing perceptual uncertainty, the brain combines information from different senses to make optimal perceptual decisions and to guide behavior. However, decision making has been investigated mostly in unimodal contexts. Thus, how the brain integrates multisensory information during decision making is still unclear. Two opposing, but not mutually exclusive, scenarios are plausible: either the brain thoroughly combines the signals from different modalities before starting to build a supramodal decision, or unimodal signals are integrated during decision formation. To answer this question, we devised a paradigm mimicking naturalistic situations where human participants were exposed to continuous cacophonous audiovisual inputs containing an unpredictable signal cue in one or two modalities and had to perform a signal detection task or a cue categorization task. First, model-based analyses of behavioral data indicated that multisensory integration takes place alongside perceptual decision making. Next, using supervised machine learning on concurrently recorded EEG, we identified neural signatures of two processing stages: sensory encoding and decision formation. Generalization analyses across experimental conditions and time revealed that multisensory cues were processed faster during both stages. We further established that acceleration of neural dynamics during sensory encoding and decision formation was directly linked to multisensory integration. Our results were consistent across both signal detection and categorization tasks. Taken together, the results revealed a continuous dynamic interplay between multisensory integration and decision making processes (mixed scenario), with integration of multimodal information taking place both during sensory encoding as well as decision formation.

Comparing exponential race and signal detection models of encoding stimuli into visual short-term memory.

The exponential race model embodied in the theory of visual attention (TVA) and the power law generalization of the sample size model (SSPL) provide competing accounts of the mechanisms that determine how exposure duration, set size, and attention influence how many items enter visual short-term memory (VSTM). In the exponential race model, items compete for entry into VSTM in a processing race with exponentially distributed processing times. The most recent version of the sample size model assumes that target sensitivity measured by d' increases monotonically as a function of exposure duration and decreases as a power function of set size. Here we compare the two models in a new experiment with letters and Gabor patches and with data from five previously published experiments. This was done by applying TVA to the two-alternative forced-choice method (2AFC), which forms the basis of the experimental work on the sample size model. Both models fitted individual participants' proportions of correct trials quite well, and overall the fits by the two models were almost indistinguishable. This was confirmed by formal pairwise comparison of TVA and SSPL by the Akaike information criterion and the Bayesian information criterion measures. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

The unequal variance signal-detection model of recognition memory: Investigating the encoding variability hypothesis.

Despite the unequal variance signal-detection (UVSD) model's prominence as a model of recognition memory, a psychological explanation for the unequal variance assumption has yet to be verified. According to the encoding variability hypothesis, old item memory strength variance (σo) is greater than that of new items because items are incremented by variable, rather than fixed, amounts of strength at encoding. Conditions that increase encoding variability should therefore result in greater estimates of σo. We conducted three experiments to test this prediction. In Experiment 1, encoding variability was manipulated by presenting items for a fixed or variable (normally distributed) duration at study. In Experiment 2, we used an attentional manipulation whereby participants studied items while performing an auditory one-back task in which distractors were presented at fixed or variable intervals. In Experiment 3, participants studied stimuli with either high or low variance in word frequency. Across experiments, estimates of σo were unaffected by our attempts to manipulate encoding variability, even though the manipulations weakly affected subsequent recognition. Instead, estimates of σo tended to be positively correlated with estimates of the mean difference in strength between new and studied items (d), as might be expected if σo generally scales with d. Our results show that it is surprisingly hard to successfully manipulate encoding variability, and they provide a signpost for others seeking to test the encoding variability hypothesis.

Inhibitory Control in Sexually Coercive Men: Behavioral Insights Using a Stop-Signal Task With Neutral, Emotional, and Erotic Stimuli.

Response inhibition is defined as one's ability to voluntarily override an automatic or already initiated action when that action is inappropriate. Although a core mechanism of self-control, its association with sexual coercion perpetration and the impact of erotic cues on its exertion remain unknown. According to a domain-specific perspective on impulsivity, response inhibition performances should be disproportionately hindered by sexual cues in sexual coercion perpetrators. In total, 94 male college students completed a stop-signal task that included neutral, emotional, and erotic distracters. Results showed that men who reported past use of sexual coercion obtained overall poorer stop-signal task (SST) performances. Highly arousing sexual stimuli equally hindered the performances of perpetrators and non-perpetrators, whereas moderately arousing sexual and nonsexual positive stimuli did not significantly affect performances. Results do not support a domain-specific perspective on the link between response inhibition and sexual coercion, but rather suggest generally poorer inhibitory control among sexual coercion perpetrators.

Metacognitive processing in language learning tasks is affected by bilingualism.

We assessed the effect of bilingualism on metacognitive processing in the artificial language learning task, in 2 experiments varying in the difficulty to segment the language. Following a study phase in which participants were exposed to the artificial language, segmentation performance was assessed by means of a dual forced-choice recognition test followed by confidence judgments. We used a signal detection approach to estimate type 1 performance (i.e., the participants' ability to discriminate statistical words vs. foils constructed from the same syllables) and type 2 metacognitive performance (i.e., the ability to discriminate the correctness of the type 1 decisions by confidence ratings). The results showed that bilinguals and monolinguals do not differ in type 1 recognition performance, but across the 2 experiments, metacognitive performance was higher in bilinguals compared with monolinguals. The results show that bilingualism improves metacognitive evaluation of performance in linguistic domains. We suggest that the improvement in metacognitive performance stems from bilinguals' enhanced error-monitoring abilities in language domain, which is also modulated by individual experience. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Transient inhibition of the cerebellum impairs change-detection processes: Cerebellar contributions to sensorimotor integration.

Patients with cerebellar lesions have shown altered responses to unpredictable stimuli. This finding has led to the belief that the cerebellum is involved in comparing incoming stimuli with previously experienced stimuli in order to predict and coordinate responses. The role of the cerebellum is thought to extend beyond motor control to higher-order executive functions, which allow for the evaluation of stimuli that influence our personal reactions, emotions, and thoughts. This current study tested the role of the cerebellum on cognitive function by examining incoming sensory stimuli being unattended by the participant. Median and ulnar nerve somatosensory evoked potentials (SEPs) were elicited by electrical stimulation via surface electrodes. Nerve stimulation was presented in an oddball fashion where median and ulnar stimulation were presented as frequent and deviant stimuli, respectively. Electroencephalography (EEG) was used to measure participants' cortical responses both before and after either continuous theta burst stimulation (cTBS) used to transiently inhibit cerebellar activity, or a sham condition. The N140 was shown to be modulated in response to deviant stimuli, resulting in a large negativity pre-cTBS, referred to as the mismatch-negativity (MMN). Following cTBS, the MMN was reduced, resulting in similar waveform patterns in response to both the frequent and deviant stimuli. The mechanisms that are thought to modulate this change within the N140 in response to deviant stimuli are believed to be different from those that govern its response to frequent stimuli. The cerebellum may be involved in attentive change-detection processes that are critical for a wide-range of everyday processes.

Spontaneous attribution of false beliefs in adults examined using a signal detection approach.

Understanding other people have beliefs different from ours or different from reality is critical to social interaction. Previous studies suggest that healthy adults possess an implicit mentalising system, but alternative explanations for data from reaction time false belief tasks have also been given. In this study, we combined signal detection theory (SDT) with a false belief task. As application of SDT allows us to separate perceptual sensitivity from criteria, we are able to investigate how another person's beliefs change the participant's perception of near-threshold stimuli. Participants (n = 55) watched four different videos in which an actor saw (or did not see) a Gabor cube hidden (or not hidden) behind an occluder. At the end of each video, the occluder vanished revealing a cube either with or without Gabor pattern, and participants needed to report whether they saw the Gabor pattern or not. A pre-registered analysis with classical statistics weakly suggests an effect of the actor's belief on participant's perceptions. An exploratory Bayesian analysis supports the idea that when the actor believed the cube was present, participants made slower and more liberal judgements. Although these data are not definitive, these current results indicate the value of new measures for understanding implicit false belief processing.

Theoretical note: Exploring Luce's (1963) low-threshold model applied to recognition memory.

Whether recognition memory is mediated by discrete or continuous processes has long been the subject of debate. Deemed "the ignored alternative" by Kellen, Erdfelder, Malmberg, Dubé, and Criss (2016), Luce's (1963) low-threshold model is a discrete model that describes data thought to be indicative of continuous mediation. Kellen et al. found that the low-threshold model describes data quantitatively as well as signal detection theory, a continuous model. We replicate that finding here across 8 experiments. More interestingly, we find that this equivalence is because of the 2 models fitting different aspects of the data-the low-threshold model better fits strongly encoded stimuli, and signal detection theory better fits weakly encoded stimuli. An alternative framework for recognition memory may be necessary-one that incorporates a control process that can induce either continuous or discrete mediation. According to this framework, meta-cognitive judgments regarding the strength of an item may induce the strategic discretization of memory. (PsycINFO Database Record (c) 2020 APA, all rights reserved).