Analyses of response time data in the same-different task.

The Same-Different task presents two stimuli in close succession and participants must indicate whether they are completely identical or if there are any attributes that differ. While the task is simple, its results have proven difficult to explain. Notably, response times are characterized by a fast-same effect whereby Same responses are faster than Different responses even though identical stimuli should be exhaustively processed to be accurate. Herein, we examine a little more than a quarter million response times (N = 255,744) obtained from 327 participants who participated in one of 14 variants of the task involving minor changes in the stimuli or their durations. We performed distribution fitting and analyzed estimated parameters stemming from the ex-Gaussian, lognormal, and Weibull distributions to infer the cognitive processing characteristics underlying this task. The results exclude serial processing of the stimuli and do not support dual-route processing. The fast-same effect appears only through a shift of the entire response time distributions, a feature impossible to detect solely with mean response time analyses. An attention-modulated process driven by entropy may be the most adequate model of the fast-same effect. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Is the fast-same phenomenon that fast? An investigation of identity priming in the same-different task.

The same-different task is a classic paradigm that requires participants to judge whether two successively presented stimuli are the same or different. While this task is simple, with results that have been replicated many times, response times (RTs) and accuracy for both same and different decisions remain difficult to model. The biggest obstacle in modeling the task lies within its effect referred to as the fast-same phenomenon whereby participants are much faster at responding "same" than "different," while most standard cognitive models predict the opposite. In this study, we investigated whether this effect is the result of identity priming activated by the first stimulus. We ran four variants of the same-different task in which identity priming is intended to be attenuated or cancelled in half of the trials. Results for all four variants show that a complete visual match between both stimuli is necessary to observe a fast-same effect and that hampering this relation attenuates same RTs while different RTs remained relatively unchanged. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Complexing deoxyribozymes with RNA aptamers for detection of the small molecule theophylline.

Biointegrative information processing systems offer a great advantage to autonomous biodevices, as their capacity for biological computation provides the ability to sense the state of more complex environments and better integrate with downstream biological regulation systems. Deoxyribozymes (DNAzymes) and aptamers are of interest to such computational biosensing systems due to the enzymatic properties of DNAzymes and the ligand-inducible conformational structures of aptamers. Herein, we describe a novel method for providing ligand-responsive allosteric control to a DNAzyme using an RNA aptamer. We designed a NOT-logic-compliant E6 DNAzyme to be complementary to an RNA aptamer targeting theophylline, such that the aptamer competitively interacted with either theophylline or the DNAzyme, and disabled the DNAzyme only when theophylline concentration was below a given threshold. Out of our seven designed "complexing aptazymes," three demonstrated effective theophylline-responsive allosteric regulation (2.84 ± 3.75%, 4.97 ± 2.92%, and 8.91 ± 4.19% activity in the absence of theophylline; 46.29 ± 3.36%, 50.70 ± 10.15%, and 61.26 ± 6.18% activity in the presence of theophylline). Moreover, the same three complexing aptazymes also demonstrated the ability to semi-quantitatively determine the concentration of theophylline present in solution, successfully discriminating between therapeutically ineffective (<20 µM), safe (20-100 µM), and toxic (>100 µM) theophylline concentrations. Our method of using an RNA aptamer for ligand-responsive allosteric control of a DNAzyme expands the way aptamers can be configured for biosensing, and suggests a pathway for embedding DNAzymes to provide enhanced information processing and control of biological systems.

Repeated Reuse of Deoxyribozyme-Based Logic Gates.

Deoxyribozymes (DNAzymes) have demonstrated a significant capacity for biocomputing and hold promise for information processing within advanced biological devices if several key capabilities are developed. One required capability is reuse-having DNAzyme logic gates be cyclically, and controllably, activated and deactivated. We designed an oligonucleotide-based system for DNAzyme reuse that could (1) remove previously bound inputs by addition of complementary oligonucleotides via toe-hold mediated binding and (2) diminish output signal through the addition of quencher-labeled oligonucleotides complementary to the fluorophore-bound substrate. Our system demonstrated, for the first time, the ability for DNAzymes to have their activity toggled, with activity returning to 90-125% of original activity. This toggling could be performed multiple times with control being exerted over when the toggling occurs, with three clear cycles observed before the variability in activity became too great. Our data also demonstrated that fluorescent output of the DNAzyme activity could be actively removed and regenerated. This reuse system can increase the efficiency of DNAzyme-based logic circuits by reducing the number of redundant oligonucleotides and is critical for future development of reusable biodevices controlled by logical operations.

Characterisation of Reproduction-Associated Genes and Peptides in the Pest Land Snail, Theba pisana.

Increased understanding of the molecular components involved in reproduction may assist in understanding the evolutionary adaptations used by animals, including hermaphrodites, to produce offspring and retain a continuation of their lineage. In this study, we focus on the Mediterranean snail, Theba pisana, a hermaphroditic land snail that has become a highly invasive pest species within agricultural areas throughout the world. Our analysis of T. pisana CNS tissue has revealed gene transcripts encoding molluscan reproduction-associated proteins including APGWamide, gonadotropin-releasing hormone (GnRH) and an egg-laying hormone (ELH). ELH isoform 1 (ELH1) is known to be a potent reproductive peptide hormone involved in ovulation and egg-laying in some aquatic molluscs. Two other non-CNS ELH isoforms were also present in T. pisana (Tpi-ELH2 and Tpi-ELH3) within the snail dart sac and mucous glands. Bioactivity of a synthetic ELH1 on sexually mature T. pisana was confirmed through bioassay, with snails showing ELH1-induced egg-laying behaviours, including soil burrowing and oviposition. In summary, this study presents a detailed molecular analysis of reproductive neuropeptide genes in a land snail and provides a foundation for understanding ELH function.

Constructing a group distribution from individual distributions.

A group distribution is a synthesis of a set of individual distributions. To be adequate, a method for creating group distributions should not introduce characteristics that are not present in the individual distributions and preserve those that are present. A method occasionally used is quantile averaging (sometimes called vincentizations), applied generally to response time distributions. However, it is shown here using quantile-quantile plots on empirical response times that this method is inadequate. As shown by Thomas and Ross (1980, Journal of Mathematical Psychology), to solve this problem, quantile averaging can be generalised using an appropriate nonlinear transformation of the data. Here we argue that the correct transformation is the log transform of response times to which the base response time has been removed. Equivalently, the geometric mean of the quantiles can be used. We first propose 4 estimates of the base response times. We next examine empirical data in a same-different task, in a redundant-attribute target detection task and in a visual search task. The results show that this approach is appropriate to construct group distributions. It can be used to aggregate distributions over multiple participants, over multiple sessions of training for a given participant, or both. (PsycINFO Database Record