PASSENGER RESPONSE TIME DATA-SETS FOR LARGE PASSENGER FERRIES AND CRUISE SHIPS DERIVED FROM SEA TRIALS

This paper describes research that was carried-out under the EU FP7 research project SAFEGUARD and presents passenger response time data generated from five full-scale semi-unannounced assembly trials at sea. The data-sets were generated from three different types of passenger ships, a RO-PAX ferry without cabins (RP1), a cruise ship (CS) and a RO-PAX ferry with cabins (RP2). In total, response times from 2366 people were collected making it the largest response time data-set ever collected – on land or sea. The analysis methodology used to extract the response time data and the resultant response time distributions (RTD) is presented. A number of key findings from the data analysis are presented along with three recommendations to modify the IMO guidelines governing ship evacuation analysis, namely; (a) it is inappropriate to use the same RTD for cruise ships and RO-PAX vessels; (b) a new Day Case RTD is suggested for RO-PAX vessels and (c) new Day and Night RTDs are suggested for cruise ships.

A Discrete Formulation of Two Alternative Forced Choice Decision Dynamics Derived from a Double-Well Quantum Landscape

Tools from quantum theory have been effectively leveraged in modeling otherwise poorly understood effects in decision-making such as apparent fallacies in probability judgments and context effects. This approach has described the dynamics of two alternative forced choice (2AFC) decisions in terms of the path of a single quantum particle evolving in a single potential well. Here, we present a variant on that approach, which we name the Multi-Particle and Multi-Well (MPMW) quantum cognitive framework, in which decisions among N alternatives are treated by the sum of positional measurements of many independent quantum particles representing stimulus information, acted on by an N-well landscape that defines the decision alternatives. In this article, we apply the MPMW model to the simplest and most common case of N-alternative decision making, 2AFC dynamics. This application calls for a multi-particle double-well implementation, which allows us to construct a simple, analytically tractable discrete drift diffusion model (DDM), in the form of a Markov chain, wherein the parameters of the attractor wells reflect bottom-up (automatic) and top-down (control-dependent) influences on the integration of external information. We first analyze this Markov chain in its simplest form, as a single integrator with a generative process arising from a static quantum landscape and fixed thresholds, and then consider the case of multi-integrator processing under the same conditions. Within this system, stochasticity arises directly from the double-well quantum attractor landscape as a function of the dimensions of its wells, rather than as an external parameter requiring independent fitting. The simplicity of the Markov chain component of this model allows for easy analytical computation of closed forms for response time distributions and response probabilities that match qualitative properties of the accuracies and reaction times of humans performing 2AFC tasks. The MPMW framework produces response time distributions following inverse gaussian curves familiar from previous DDM models and empirical data, including the common observation that mean response times are faster for incorrect than for correct responses. The work presented in this paper serves as a proof of concept, based on which the MPMW framework can be extended to address more complex decision-making processes, (e.g., N-alternative forced choice, dynamic control allocation, and nesting quantum landscapes to allow for modeling at both the task and stimulus levels of processing) that we discuss as future directions.

Understanding the Structure of Cognitive Noise

Human cognition is fundamentally noisy. While routinely regarded as a nuisance in experimental investigation, the few studies investigating properties of cognitive noise have found surprising structure. A first line of research has shown that inter-response-time distributions are heavy-tailed. That is, response times between subsequent trials usually change only a small amount, but with occasional large changes. A second, separate, line of research has found that participants’ estimates and response times both exhibit long-range autocorrelations (i.e., 1/f noise). Thus, each judgment and response time not only depends on its immediate predecessor but also on many previous responses. These two lines of research use different tasks and have distinct theoretical explanations: models that account for heavy-tailed response times do not predict 1/f autocorrelations and vice versa. Here, we find that 1/f noise and heavy-tailed response distributions co-occur in both types of tasks. We also show that a statistical sampling algorithm, developed to deal with patchy environments, generates both heavy-tailed distributions and 1/f noise, suggesting that cognitive noise may be a functional adaptation to dealing with a complex world.

Bilingual speakers' enhanced monitoring can slow them down

Performance differences between bilingual and monolingual participants on conflict tasks can be affected by the balance of various sub-processes such as monitoring and stimulus categorisation. Here we investigated the effect of bilingualism on these sub-processes during a conflict task with medium monitoring demand. We examined the behavioural and evoked potentials from a group of bilingual and monolingual speakers during a flanker task with 25% incongruent trials. We analysed behavioural differences by means of averaged response times and ex-Gaussian analyses of response time distributions. For the evoked potentials we focused on the N2 (implicated to be involved in monitoring) and P300 (implicated to be involved in categorisation) responses. We found that bilinguals had significantly longer response distribution tails compared to monolinguals. Additionally, bilinguals exhibited a more pronounced N2 and smaller P3 components compared to their monolingual counterparts, independent of experimental condition, suggesting enhanced monitoring processes and reduced categorisation effort. Importantly, N2 amplitudes were positively and P3 amplitudes were negatively related to the length of response distribution tails. We postulate that these results reflect an overactive monitoring system in bilinguals in a task of medium monitoring demand. This enhanced monitoring leads to less effortful categorisation, but also occasionally to slow responses. These results suggest that changes of the cognitive control system due to bilingual experience changes the balance of processes during conflict tasks, potentially leading to a small behavioural disadvantage.

Impact of antecedent wetness and precipitation intensity on catchment travel and response times

<p>The time a molecule of rain takes to reach the stream is normally substantially longer than the time for discharge to respond to rainfall. This difference arises because hydraulic potentials propagate through landscapes much faster than water itself does; in other words, the celerity of wave propagation is faster than the velocity of water flow. Although these concepts are well established, most catchment studies are restricted to the calculation of the celerity or response time from hydrometric information. However, to understand the storage, release, and transport of water, as well as identify flow paths through the catchment, one needs to estimate both response and travel times, requiring both hydrometric and tracer data.</p><p>We analyzed hydrometric and tracer data from two contrasting sites, the pre-Alpine Erlenbach catchment in Switzerland and the Upper Hafren catchment at Plynlimon in Wales. For both sites, hydrometric data and sub-daily isotopic tracer time series are available, enabling the calculation of response times as well as travel time distributions and new water fractions. To gain a deeper understanding of the functioning of the two catchments, we quantified these metrics and distributions for different ranges of antecedent wetness and precipitation intensity. Generally, wetter catchment conditions and higher precipitation intensities yielded faster runoff responses and shorter travel times.  Contrasts between travel and response time distributions under varying catchment conditions also facilitated more nuanced insights into catchment functioning and the effects of catchment wetness and precipitation intensity on water storage and release.</p>

Identifying distributions of response times in karst aquifers

<p>In karst catchments, aquifer recharge occurs through a composite mosaic of subsurface flow paths. Precipitation infiltrates in the subsurface and flows along a complex network of fractures – that are characterized by different sizes and degrees of saturation –  before eventually reaching the catchment outlet. The discharge of a karst spring is the result of the contributions of these flow paths, that may differ widely in terms of lengths, velocities, and travel times. Monitoring the spring discharge can thus provide information about flow within the aquifer. In particular, the spring discharge signal can be interpreted as the lagged response of the aquifer to precipitation inputs over the catchment, with the aquifer being characterized by a distribution of response times that relates input (precipitation) to output (discharge). Identifying these response times is not a trivial task as the input-output problem is often mathematically ill-posed, which leads to amplification of the errors and may prevent finding a physically meaningful solution.</p><p>In this work we propose a method to evaluate the distribution of response times of a karst aquifer. The method, that was originally developed to deal with ill-posed problems in geostatistical applications, relies on a probabilistic description of precipitation inputs and discharge outputs, and it provides an estimate of the response time distribution and of its uncertainty. The method is here tested through the application to two datasets collected in two cave systems in Northern Italy (the Bossea system and the Vene/Fuse system) with different hydrogeological properties. The results demonstrate that the method successfully identifies different response time distributions that reflect the differences in aquifer characteristics of the two systems. Furthermore, differences among response time distributions relative to different precipitation events in each system provide valuable insights on seasonal variations in aquifer recharge and fracture saturation. The method can hence be applied as a tool for the indirect investigation of karst systems.</p>

Beyond Looking for the Rewarded Target: The Effects of Reward on Attention in Search Tasks

One puzzling result in training-test paradigms is that effects of reward-associated stimuli on attention are often seen in test but not in training. We focus on one study, where reward-related performance benefits occur in the training and which was discussed contentiously. By using a similar design, we conceptually replicated the results. Moreover, we investigated the underlying mechanisms and processes resulting in these reward-related performance benefits. In two experiments, using search tasks and having participants perform the tasks either with or without individually adjusted time pressure, we disentangled the mechanisms and processes contributing to the reward-related benefits. We found evidence that not only search efficiency is increased with increasing reward, but also that non-search factors contribute to the results. By also investigating response time distributions, we were able to show that reward-related performance effects increased as search time increased in demanding tasks but not in less demanding tasks. Theoretical implications of the results regarding how reward influences attentional processing are discussed.

A two-stage diffusion modeling approach to the compelled-response task

The issue of how perception and motor planning interact to generate a given choice between actions is a fundamental question in both psychology and neuroscience. Salinas and colleagues have developed a behavioral paradigm, the compelled-response task, where the signal that instructs the subject to make an eye movement is given before the cue that indicates which of two possible target choices is the correct one. When the cue is given rather late, the participant must guess and make an uninformed random choice. Perceptual performance can be tracked as a function of the amount of time during which sensory information is available. In Salina’s accelerated race-to-threshold model, two variables race against each other to a threshold, at which a saccade is initiated. The source of random variability is in the initial state of information buildup across trials. This implies that incorrect decisions are due to the inertia of the racing variables that have, at the start, sampled a constant buildup in the “wrong” direction. Here we suggest an alternative, non-time-homogeneous two-stage-diffusion model that is able to predict both response time distributions and choice probabilities with a few easy-to-interpret parameters and without assuming cross-trial parameter variability. It is falsifiable at the level of qualitative features already, e.g. predicting bimodal RT distributions for particular gap times. It connects the compelled-response paradigm with an approach to decision making that has been uniquely successful in describing both behavioral and neural data in a variety of experimental settings for the last 40 years.

Retrospective auditory cues can improve detection of near-threshold visual targets

Recent studies have demonstrated that visually cueing attention towards a stimulus location after its disappearance can facilitate visual processing of the target and increase task performance. Here, we tested whether such retro-cueing effects can also occur across different sensory modalities, as cross-modal facilitation has been shown in pre-cueing studies using auditory stimuli prior to the onset of a visual target. In the present study, participants detected low-contrast Gabor patches in a speeded response task. These patches were presented in the left or right visual periphery, preceded or followed by a lateralized and task-irrelevant sound at 4 stimulus-onset asynchronies (SOA; −600 ms, −150 ms, +150 ms, +450 ms). We found that pre-cueing at the −150 ms SOA led to a general increase in detection performance irrespective of the sound’s location relative to the target. On top of this temporal effect, sound-cues also had a spatially specific effect, with further improvement when cue and target originated from the same location. Critically, the temporal effect was absent, but the spatial effect was present in the short-SOA retro-cueing condition (+150 ms). Drift-diffusion analysis of the response time distributions allowed us to better characterize the evidenced effects. Overall, our results show that sounds can facilitate visual processing, both pre- and retro-actively, indicative of a flexible and multisensory attentional system that underlies our conscious visual experience.