New Set Of Stimuli Research Articles

Co-existence of synaptic plasticity and metastable dynamics in a spiking model of cortical circuits.

Evidence for metastable dynamics and its role in brain function is emerging at a fast pace and is changing our understanding of neural coding by putting an emphasis on hidden states of transient activity. Clustered networks of spiking neurons have enhanced synaptic connections among groups of neurons forming structures called cell assemblies; such networks are capable of producing metastable dynamics that is in agreement with many experimental results. However, it is unclear how a clustered network structure producing metastable dynamics may emerge from a fully local plasticity rule, i.e., a plasticity rule where each synapse has only access to the activity of the neurons it connects (as opposed to the activity of other neurons or other synapses). Here, we propose a local plasticity rule producing ongoing metastable dynamics in a deterministic, recurrent network of spiking neurons. The metastable dynamics co-exists with ongoing plasticity and is the consequence of a self-tuning mechanism that keeps the synaptic weights close to the instability line where memories are spontaneously reactivated. In turn, the synaptic structure is stable to ongoing dynamics and random perturbations, yet it remains sufficiently plastic to remap sensory representations to encode new sets of stimuli. Both the plasticity rule and the metastable dynamics scale well with network size, with synaptic stability increasing with the number of neurons. Overall, our results show that it is possible to generate metastable dynamics over meaningful hidden states using a simple but biologically plausible plasticity rule which co-exists with ongoing neural dynamics.

Co-existence of synaptic plasticity and metastable dynamics in a spiking model of cortical circuits.

Evidence for metastable dynamics and its role in brain function is emerging at a fast pace and is changing our understanding of neural coding by putting an emphasis on hidden states of transient activity. Clustered networks of spiking neurons have enhanced synaptic connections among groups of neurons forming structures called cell assemblies; such networks are capable of producing metastable dynamics that is in agreement with many experimental results. However, it is unclear how a clustered network structure producing metastable dynamics may emerge from a fully local plasticity rule, i.e., a plasticity rule where each synapse has only access to the activity of the neurons it connects (as opposed to the activity of other neurons or other synapses). Here, we propose a local plasticity rule producing ongoing metastable dynamics in a deterministic, recurrent network of spiking neurons. The metastable dynamics co-exists with ongoing plasticity and is the consequence of a self-tuning mechanism that keeps the synaptic weights close to the instability line where memories are spontaneously reactivated. In turn, the synaptic structure is stable to ongoing dynamics and random perturbations, yet it remains sufficiently plastic to remap sensory representations to encode new sets of stimuli. Both the plasticity rule and the metastable dynamics scale well with network size, with synaptic stability increasing with the number of neurons. Overall, our results show that it is possible to generate metastable dynamics over meaningful hidden states using a simple but biologically plausible plasticity rule which co-exists with ongoing neural dynamics.

Metrical segmentation across dialects

Norris, McQueen & Cutler (1995) tested the Metrical Segmentation Strategy (MSS; Cutler & Norris, 1988) as part of the spoken-word recognition model Shortlist, using British English stimuli and listeners. We replicate their study using American English listeners, who we exposed to one of two sets of stimuli. One group heard a new set of stimuli recorded in American English, while the other was exposed to the original British English recordings. Norris et al. used a word-spotting task: listeners had to spot words within speech (e.g. “stamp” in [stæmpɪdʒ]). Target words were CVCC (like “champ") or CVC (like “done"), and were followed by a full vowel (e.g. /tʃæmpoʊʃ/) or a reduced vowel (e.g. /tʃæmpəʃ/). The original study found different behavior for CVCC versus CVC targets, with the results suggesting that listeners hypothesize a word onset at the start of a full-vowel strong syllable (the MSS). The results for the current study with American stimuli partially replicate the original findings, showing even more consistent support for the MSS. The results with British stimuli also support the MSS, but with higher error rates. The results indicate that the MSS has a very strong effect even in the difficult setting of cross-dialectal perception.

A novel approach to the assessment of higher-order rule learning in male mice.

Historically, the development of valid and reliable methods for assessing higher-order cognitive abilities (e.g., rule learning and transfer) has been difficult in rodent models. To date, limited evidence supports the existence of higher cognitive abilities such as rule generation and complex decision-making in mice, rats, and rabbits. To this end, we sought to develop a task that would require mice to learn and transfer a rule. We trained mice to visually discriminate a series of images (image set, six total) of increasing complexity following three stages: (1) learn a visual target, (2) learn a rule (ignore any new images around the target), and finally (3) apply this rule in abstract form to a comparable but new image set. To evaluate learning for each stage, we measured (1) days (and performance by day) to discriminate the original target at criterion, (2) days (and performance by day) to get back to criterion when images in the set were altered by the introduction of distractors (rule learning), and (3) overall days (and performance by day) to criterion when experienced versus naïve cohorts of mice were tested on the same image set (rule transfer). Twenty-seven wild-type male C57 mice were tested using Bussey-Saksida touchscreen operant conditioning boxes (Lafayette Instruments). Two comparable black-white image sets were delivered sequentially (counterbalanced for order) to two identical cohorts of mice. Results showed that all mice were able to effectively learn their initial target image and could recall it >80 d later. We also found that mice were able to quickly learn and apply a "rule" : Ignore new distractors and continue to identify their visual target embedded in more complex images. The presence of rule learning was supported because performance criterion thresholds were regained much faster than initial learning when distractors were introduced. On the other hand, mice appeared unable to transfer this rule to a new set of stimuli. This is supported because visual discrimination curves for a new image set were no better than an initial (naïve) learning by a matched cohort of mice. Overall results have important implications for phenotyping research and particularly for the modeling of complex disorders in mice.

Teams moving more synchronously are perceived as socially dominant

Characteristics indicative of individual and group power can be used to judge social dominance. The present study investigated whether observers use movement synchrony to judge the dominance of teams during a social conflict. How synchronously individuals move together has been found to influence judgments of team effectiveness and the formidability of groups. Across four experiments, the present study examined whether movement synchrony is also used as a cue of team dominance. Experiment 1 provided evidence that teams of animated characters with higher movement synchrony were judged as more likely to win a competition and were rated as more dominant. A similar effect of synchrony on teams winning a competition was observed in Experiment 2 with different types of movement. Experiment 3 replicated the effects of the prior experiments: teams that moved more synchronously were judged as more likely to win a competition and rated as more socially dominant. These effects were extended in Experiment 4 with a new set of stimuli, human-like avatars performing complex dance actions, replicating synchrony-effects with different types of characters. This research indicates that human observers use movement synchrony to judge the social dominance of teams. This expands the types of behavioral cues that are used to predict the power of teams when social conflicts occur.

The cultural adaptation of quantity judgment tasks in Ghanaian English and Akan

The phenomenon of mass and countability is multifaceted and has been controversially discussed in many disciplines. For linguistics, differences in the morphosyntactic marking of the distinction cross-linguistically, and its cross-cultural ontological-semantic conceptualization are particularly interesting. However, most studies into mass and countability have focused on (American) English, and, to some extent European and Asian languages. African languages and contexts have as yet been neglected by researchinto countability, and the methodological tools employed to study it do not account for the ambient cultural contexts. This paper presents the results of a quantity judgment task designed according to Barner and Snedeker’s (2005) experiment for American English speakers, conducted in Ghanaian English and Akan. The Ghanaian experiments reveal important concerns regarding the stimuli and their applicability, especially to Akan culture. Thus, inspired by other studies into the semantics of Akan, a new set of stimuli is suggested in order to investigate mass and countability contrastively in Ghanaian English and Akan. In this vein, they emphasize the insufficiency of translations with regard to (psycho)linguistic experiments and the importance of proper cultural adaptation.

네이밍 유도에 필요한 매칭 교수 시도 수가 발달장애 아동의 네이밍(Naming) 출현에 가지는 의미

In the present study, number of matching instruction trials required to induce Naming was analyzed using Naming probe procedure which was reported in existing literature. Then the identified number of matching trials with new sets of stimuli was provided to examine whether Naming responses emerged in children with language delays. A delayed multiple baselines across behaviors with multiple probes design was used and this experimental procedure was repeated with Participant B. The results of this study showed that both of participant showed emergence of Naming capabilities to novel sets of stimuli when the identified number of matching trials were provided. The results of this study suggested that one of main variables for emergence of Naming was number of opportunities in which the participants were exposed to stimuli before they reached to a criterion level during pointing or tact instruction with the stimuli. In future studies, relationship between number of trials to criteria during the listener or speaker instruction and emergence of Naming capability should be examined.

Effects of an Audiovisual Emotion Perception Training for Schizophrenia: A Preliminary Study

Individuals with schizophrenia show a reduced ability to integrate facial and vocal information in emotion perception. Although emotion perception has been a target for treatment, no study has yet examined the effect of multimodal training on emotion perception in schizophrenia. In the present study, we developed an audiovisual emotion perception training and test in which a voice and a face were simultaneously presented, and subjects were asked to judge whether the emotions of the voice and the face matched. The voices were either angry or happy, and the faces were morphed on a continuum ranging from angry to happy. Sixteen patients with schizophrenia participated in six training sessions and three test sessions (i.e., pre-training, post-training, and generalization). Eighteen healthy controls participated only in pre-training test session. Prior to training, the patients with schizophrenia performed significantly worse than did the controls in the recognition of anger; however, following the training, the patients showed a significant improvement in recognizing anger, which was maintained and generalized to a new set of stimuli. The patients also improved the recognition of happiness following the training, but this effect was not maintained or generalized. These results provide preliminary evidence that a multimodal, audiovisual training may yield improvements in anger perception for patients with schizophrenia.

Boundaries in space and time: Iconic biases across modalities

The idea that the form of a word reflects information about its meaning has its roots in Platonic philosophy, and has been experimentally investigated for concrete, sensory-based properties since the early 20th century. Here, we provide evidence for an abstract property of ‘boundedness’ that introduces a systematic, iconic bias on the phonological expectations of a novel lexicon. We show that this abstract property is general across events and objects. In Experiment 1, we show that subjects are systematically more likely to associate sign language signs that end with a gestural boundary with telic verbs (denoting events with temporal boundaries, e.g., die, arrive) and with count nouns (denoting objects with spatial boundaries, e.g., ball, coin). In Experiments 2–3, we show that this iconic mapping acts on conceptual representations, not on grammatical features. Specifically, the mapping does not carry over to psychological nouns (e.g. people are not more likely to associate a gestural boundary with idea than with knowledge). Although these psychological nouns are still syntactically encoded as either count or mass, they do not denote objects that are conceived of as having spatial boundaries. The mapping bias thus breaks down. Experiments 4–5 replicate these findings with a new set of stimuli. Finally, in Experiments 6–11, we explore possible extensions to a similar bias for spoken language stimuli, with mixed results. Generally, the results here suggest that ‘boundedness’ of words' referents (in space or time) has a powerful effect on intuitions regarding the form that the words should take.

Attractiveness and distinctiveness between speakers' voices in naturalistic speech and their faces are uncorrelated.

Facial attractiveness has been linked to the averageness (or typicality) of a face and, more tentatively, to a speaker's vocal attractiveness, via the ‘honest signal’ hypothesis, holding that attractiveness signals good genes. In four experiments, we assessed ratings for attractiveness and two common measures of distinctiveness (‘distinctiveness-in-the-crowd’, DITC and ‘deviation-based distinctiveness', DEV) for faces and voices (simple vowels, or more naturalistic sentences) from 64 young adult speakers (32 female). Consistent and substantial negative correlations between attractiveness and DEV generally supported the averageness account of attractiveness, for both voices and faces. By contrast, and indicating that both measures of distinctiveness reflect different constructs, correlations between attractiveness and DITC were numerically positive for faces (though small and non-significant), and significant for voices in sentence stimuli. Between faces and voices, distinctiveness ratings were uncorrelated. Remarkably, and at variance with the honest signal hypothesis, vocal and facial attractiveness were also uncorrelated in all analyses involving naturalistic, i.e. sentence-based, speech. This result pattern was confirmed using a new set of stimuli and raters (experiment 5). Overall, while our findings strongly support an averageness account of attractiveness for both domains, they provide no evidence for an honest signal account of facial and vocal attractiveness in complex naturalistic speech.

Emergent Tact Control Following Stimulus Pairing: Comparison of Procedural Variations.

We examined emergent tact control following stimulus pairing, using 2 different stimulus presentation arrangements. In the word-first condition, presentation of the auditory stimulus preceded the visual stimulus, and in the image-first condition, the visual stimulus preceded the auditory stimulus. Eight children (2-5 years old) participated. In Experiment 1, 4 children were exposed to 3 sessions in each condition with a new set of stimuli in each session. In Experiment 2, 2 of the same children received repeated exposure to the same stimulus sets. Experiment 3, with new participants, was identical to Experiment 1, except visual and auditory stimuli overlapped during the presentation. Postsession probes documented emergent stimulus control over 1 or more vocal responses for 7 of the 8 participants. Participants were more likely to make echoic responses with the visual stimulus present in the word-first condition; however, emergent tact control was unaffected by the order of the stimulus presentation. Additional research is needed on stimulus-pairing procedures and on the role of echoic responding in emergent tact control.

The influence of orthography on speech production: Evidence from masked priming in word-naming and picture-naming tasks.

In a masked priming word-naming task, a facilitation due to the initial-segmental sound overlap for 2-character kanji prime-target pairs was affected by certain orthographic properties (Yoshihara, Nakayama, Verdonschot, & Hino, 2017). That is, the facilitation that was due to the initial mora overlap occurred only when the mora was the whole pronunciation of their initial kanji characters (i.e., match pairs; e.g., /ka-se.ki/- /ka-rjo.ku/). When the shared initial mora was only a part of the kanji characters' readings, however, there was no facilitation (i.e., mismatch pairs; e.g., /ha.tu-a.N/- /ha.ku-bu.tu/). In the present study, we used a masked priming picture-naming task to investigate whether the previous results were relevant only when the orthography of targets is visually presented. In Experiment 1, the main findings of our word-naming task were fully replicated in a picture-naming task. In Experiments 2 and 3, the absence of facilitation for the mismatch pairs were confirmed with a new set of stimuli. On the other hand, a significant facilitation was observed for the match pairs that shared the 2 initial morae (in Experiment 4), which was again consistent with the results of our word-naming study. These results suggest that the orthographic properties constrain the phonological expression of masked priming for kanji words across 2 tasks that are likely to differ in how phonology is retrieved. Specifically, we propose that orthography of a word is activated online and constrains the phonological encoding processes in these tasks. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Category difference facilitates oddity learning in honeybees (Apis mellifera).

Performance of honeybees resembles that of vertebrates in a variety of associative learning experiments. Recent work has focused on relational learning phenomena not easily explained by associative principles, including same/different problems, the simplest of which is the oddity problem. Free-flying bees were trained to visit a laboratory window and were rewarded for choice of the odd stimulus among a set of stimuli. There were two stimulus categories, single-color solids and two-color patterns. The training was trial-unique, with new sets of stimuli on each trial. In Experiment 1, 4 groups were trained in a 3-stimulus oddity problem, 2 with solid odd and patterns nonodd and 2 with pattern odd and solids nonodd. For 1 group in each condition, the odd and nonodd stimuli shared a color. The performance of all groups was better than chance. The bees could solve the problem on the basis of oddity (same vs. different) or category (solid vs. pattern). These possibilities were unconfounded in Experiment 2 with 2 groups trained in a 4-stimulus oddity problem. Group 1 was trained with a category difference on each trial; the solid color was odd on half the trials and the pattern odd on the others. Group 2 was trained with no category difference; all stimuli were patterns. Both groups showed better-than-chance performance, and the irrelevant category difference facilitated oddity discrimination for Group 1. The results support previous findings of oddity learning in honeybees, the only invertebrate species for which any relational learning phenomena have been demonstrated. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Identity matching in a person with Alzheimer’s disease

ABSTRACT In the present study, a 91-year-old woman with Alzheimer’s disease participated. The purpose of the experiment was to study how repetitions of conditions affected correct responding in identity matching-to-sample. The participant was presented with identity matching training with three colors (yellow, blue, and red). It was alternated between (A) delayed matching-to-sample 0 s (DMTS 0 s) and (B) simultaneous matching-to-sample (SMTS). These two conditions were repeated in six phases in an ABABAB-design. In the second part of the experiment, the participant was exposed for the same six phases again but with another set of color stimuli (green, orange, and purple). The results showed that the number of trials needed to meet the criterion for training decreased as the conditions were repeated, also with the new set of stimuli.

Maximizing the generalization of fear extinction: Exposures to a peak generalization stimulus

Experimental research has shown that generalization of fear extinction from a generalization stimulus (GS) is minimal compared to generalization of fear extinction from the conditional stimulus itself (CS+). This poses a challenge to extinction-based treatments of anxiety because the exact CS is often not known or unavailable. However, experimental studies failed to disentangle differences in stimulus identity (CS + or GS) from differences in the level of fear (GS typically elicits less fear than CS+). Here, we test the hypothesis that a high level of fear is key to extinction learning and generalization, rather than the identity of the stimulus under extinction (CS + or GS). For that purpose, we took advantage of the peak-shift phenomenon that describes the conditions under which a GS can elicit equal or higher levels of responding, compared to the CS+. Hence, we compared the generalizability of fear extinction following exposure to the CS + itself, to a ‘weak’ GS that elicits less fear, and to a ‘peak’ GS that elicits as much fear as the CS+. First, the results replicated, with a new set of stimuli, the observation that extinction of a skin conductance response and US-expectancy generalizes only weakly from a weak GS to CS+. Second, extinction generalized strongly from a peak GS towards CS+, as hypothesized. Third, extinction with the peak GS even outperformed extinction with the CS+, as it generalized more strongly across the generalization gradient. Together, these results support exposure treatment strategies that focus on the fear-eliciting potential of stimuli (often described as a fear hierarchy), rather than their learning history. We propose that stimulus typicality and/or intensity may explain the enhanced effects of a ‘peak’ GS over the CS+ in enhancing the generalization of fear extinction.

The source and effects of binaural cue ambiguity in free-field stereo sound localization—Behavioral testing

Horizontal sound localization in free field requires integration of interaural time (ITD) and level (ILD) differences, in making accurate spatial judgments. Recently, we showed that listeners demonstrated great variability in localizing a stereo sound source (Montagne and Zhou, JASA, 2016). We hypothesized that this variability might arise from conflicting sidedness between ITDs and ILDs within and/or across frequency bands. To test this hypothesis, here we generated a new set of stimuli with variable spatial congruence between ITDs and ILDs by adding a constant inter-channel level cue ( + /- 5 dB) either aligned with or opposed to the inter-channel timing cue (from -1 to 1 msec). In Experiment 1 listeners responded to 15-ms broadband noise bursts. Response variability decreased when the inter-channel timing and level cues were spatially congruent and increased when they were not. In Experiment 2 listeners responded to low- and high-pass filtered noise (1.5 kHz cutoff) for the spatially incongruent stimuli only. Response variability was much reduced but the perceived source location consistently pointed to the “wrong side,” favoring the level cue. Together, the new results suggest a significant weighting role for ILDs (generated from level-based stereophony) in determining the lateral position of a stereo image.

Is anterior N2 enhancement a reliable electrophysiological index of concealed information?

Concealed information tests (CITs) are used to determine whether an individual possesses information about an item of interest. Event-related potential (ERP) measures in CITs have focused almost exclusively on the P3b component, showing that this component is larger when lying about the item of interest (probe) than telling the truth about control items (irrelevants). Recent studies have begun to examine other ERP components, such as the anterior N2, with mixed results. A seminal CIT study found that visual probes elicit a larger anterior N2 than irrelevants (Gamer and Berti, 2010) and suggested that this component indexes cognitive control processes engaged when lying about probes. However, this study did not control for potential intrinsic differences among the stimuli: the same probe and irrelevants were used for all participants, and there was no control condition composed of uninformed participants.Here, first we show that the N2 effect found in the study by Gamer and Berti (2010) was in large part due to stimulus differences, as the effect observed in a concealed information condition was comparable to that found in two matched control conditions without any concealed information (Experiments 1 and 2).Next, we addressed the issue of the generality of the N2 findings by counterbalancing a new set of stimuli across participants and by using a control condition with uninformed participants (Experiment 3). Results show that the probe did not elicit a larger anterior N2 than the irrelevants under these controlled conditions.These findings suggest that caution should be taken in using the N2 as an index of concealed information in CITs. Furthermore, they are a reminder that results of CIT studies (not only with ERPs) performed without stimulus counterbalancing and suitable control conditions may be confounded by differential intrinsic properties of the stimuli employed.

Categorization does not promote symmetry in Guinea baboons (Papio papio).

Humans have the capacity to use stimuli interchangeably by forming equivalence classes, and this ability seems to be supported by our language system. According to Sidman and Tailby (Conditional discrimination vs. matching to sample: an expansion of the testing paradigm. J Exp Anal Behav 37:5-22, 1982), the formation of equivalence classes require that three relations are derived among the class members, and past experiments have shown that one of these relations, i.e., symmetry, corresponding to the ability to reverse a relation (if A→B, then B→A), is extremely difficult to obtain in non-human animals. Because language development and the ability to form equivalence classes both co-occur in children with an increased ability to form categories, the current study tested the idea that category learning might promote symmetry in a nonhuman primate species. In Experiment 1, twelve Guinea baboons (Papio papio) were trained to associate 60 pictures of bears and 60 pictures of cars to two category labels, before being tested in symmetry trials. In Experiment 2, symmetry was trained and tested by reversing the association order between labels and pictures, using a new set of stimuli. In both experiments, the baboons successfully demonstrated category discrimination, but had only a weak (though significant) tendency to respond in accordance with symmetry during test trials. Altogether, our results confirm that symmetry is inherently difficult in non-human animals. We discuss possible explanations for such a limitation and give reasons for thinking that the effects of categorization on symmetry should be further investigated.

The roles of stimulus and response uncertainty in forced-choice performance: an amendment to Hick/Hyman Law.

Hick/Hyman Law describes one of the core phenomena in the study of human information processing: mean response time is a linear function of average uncertainty. In the original work of Hick, (1952) and Hyman, (1953), along with many follow-up studies, uncertainty regarding the stimulus and uncertainty regarding the response were confounded such that the relative importance of these two factors remains mostly unknown. The present work first replicates Hick/Hyman Law with a new set of stimuli and then goes on to separately estimate the roles of stimulus and response uncertainty. The results demonstrate that, for a popular type of task-visual stimuli mapped to vocal responses-response uncertainty accounts for a majority of the effect. The results justify a revised expression of Hick/Hyman Law and place strong constraints on theoretical accounts of the law, as well as models of response selection in general.

24-month-olds use conceptual similarity to solve new problems after a delay

In this experiment, we used the deferred imitation paradigm to assess 24-month-olds’ ability to use conceptual similarity to solve new problems after a delay. Infants in the experimental condition participated in four sessions that were each separated by 24 h. In Session 1, the experimenter modeled three target actions using one set of stimuli and in Session 2, infants were tested with a novel set of stimuli that could be used to perform the same target actions. To emphasize the functional similarity of the two sets of stimuli, the experimenter provided the same unique verbal label for them during the demonstration (Session 1) and the test (Session 2). In Session 3, the experimenter modeled three new target actions with another new set of stimuli, and in Session 4, infants were tested with a novel set of stimuli that could be used to perform these same target actions. No verbal cues were provided during Sessions 3 and 4. Infants in the experimental condition exhibited excellent imitation during Session 4 even though they were tested with completely different stimuli in the absence of verbal cues. The performance of the control groups illustrated that imitation in Session 4 was not based on prior successful imitation alone or on exposure to multiple stimuli across successive sessions. Instead, we conclude that infants used the conceptual relation between the imitation problems as a basis of knowledge transfer.