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In this 3-experiment study, the Weber fractions in the 300-ms and 900-ms duration ranges are obtained with 9 types of empty intervals resulting from the combinations of three types of signals for marking the beginning and end of the signals: auditory (A), visual (V), or tactile (T). There were three types of intramodal intervals (AA, TT, and VV) and 6 types of intermodal intervals (AT, AV, VA, VT, TA, and TV). The second marker is always the same during Experiments 1 (A), 2 (V), and 3 (T). With an uncertainty strategy where the first marker is 1 of 2 sensory signals being presented randomly from trial to trial, the study provides direct comparisons of the perceived length of the different marker-type intervals. The results reveal that the Weber fraction is nearly constant in the three types of intramodal intervals, but is clearly lower at 900 ms than at 300 ms in intermodal conditions. In several cases, the intramodal intervals are perceived as shorter than intermodal intervals, which is interpreted as an effect of the efficiency in detecting the second marker of an intramodal interval. There were no significant differences between the TA and VA intervals (Experiment 1) and between the AV and TV intervals (Experiment 2), but in Experiment 3, the AT intervals were perceived as longer than the VT intervals. The results are interpreted in terms of the generalized form of Weber's law, using the properties of the signals for explaining the additional nontemporal noise observed in the intermodal conditions.

Spot est une recherche-intervention qui a permis l’implantation d’un service de depistage rapide du VIH dans la communaute gaie montrealaise. Afin de decrire le processus d’implantation de Spot et les facteurs contextuels qui l’ont affecte, une etude de cas a ete menee. Les analyses qualitatives ont permis d’identifier un processus d’implantation en plusieurs phases, module par des facteurs lies aux motivations des acteurs a s’engager dans le projet, a la complexite des dynamiques partenariales, aux defis de la coordination en contexte de recherche-intervention multidisciplinaire et intersectorielle et a l’organisation de l’equipe terrain au quotidien. Spot is an intervention research project that led to the implementation of a community-based rapid HIV testing service in Montreal’s gay community. A case study was undertaken to describe the process through which Spot was implemented and the contextual factors that affected this process. Qualitative analysis allowed an implementation process comprised of several phases to be identified. These phases were shaped by stakeholders’ motivations to engage in the project; complex partnership dynamics; challenges with regards to coordinating a multidisciplinary, intersectoral, intervention research project; and the day-to-day management of the intervention team.

Gay, bisexual, and other men who have sex with men (MSM) have adapted their sexual practices over the course of the HIV/AIDS epidemic based on available data and knowledge about HIV. This study sought to identify and compare patterns in condom use among gay, bisexual, and other MSM who were tested for HIV at a community-based testing site in Montreal, Canada. Results showed that while study participants use condoms to a certain extent with HIV-positive partners and partners of unknown HIV status, they also make use of various other strategies such as adjusting to a partner's presumed or known HIV status and viral load, avoiding certain types of partners, taking PEP, and getting tested for HIV. These findings suggest that MSM who use condoms less systematically are not necessarily taking fewer precautions but may instead be combining or replacing condom use with other approaches to risk reduction.

Research in cognitive systems engineering (CSE) and decision support requires an understanding of the psychological processes involved in a given task. The purpose of the present study is to investigate how policy capturing and process tracing may help understand the decision mechanisms involved in a naval air-defense task and characterize how human decision making effectiveness can be improved. We report results from a study in which participants performed a threat evaluation and weapons assignment task within a naval air-defense microworld. Policy capturing and process tracing techniques provide both converging perspectives and complementary insights into complex decision making processes.

Tactical command and control (C2) operations under conditions of complexity, uncertainty, stress, and time pressure impose significant cognitive demands on the Tactical Army Commanders' (TAC) ability to successfully prosecute their missions. The objective of the present study was to apply Hollnagel's (1998) Contextual Control Model (COCOM) to the identification of time-critical Situation Awareness (SA) requirements for TACs engaged in time-critical tactical C2 operations. SA requirements relevant to the successful completion of a broad range of tactical C2 missions – convoy escort, checkpoint security, combat, and cordon and search – were identified. These SA requirements were then prioritized into a subset of ‘critical’ SA requirements and then further analyzed in terms of classifying them into one of four COCOM control modes (i.e., strategic, tactical, opportunistic and scrambled). Through this analysis, areas that impact the development of decision aids, and other forms of decision support techniques, for TACs were identified.

Temporal awareness is key to successful decision making in a wide range of command and control situations, yet little explicit support to maintaining temporal awareness is provided by Decision Support Systems (DSS) for time-critical decisions. In the context of simulated weapon-target scheduling, the present study compared the decision support gained from two display formats: typical geospatial display and temporal display. The results demonstrated that the temporal display facilitates scheduling performance though its beneficial impact seems to require greater familiarization.

The present study aims to investigate how teams respond to workload transition due to a sudden and unexpected event in a complex and dynamic command and control (C2) environment. The C3Fire microworld (Granlund, 1998), a forest fire-fighting simulation, is used to compare divisional (territory-specific) and functional (role-specific) teams. Workload transition is induced by the sudden appearance of a second fire. Results show that functional teams' performance decreases while their communication frequency increases following the workload transition. However, they are faster to detect the second fire. This pattern of results suggests that in the context of C2 environments, the impact of a workload escalation varies as a function of team structure (functional vs. divisional) and the type of task (fire detection vs. fire fighting).

In order to test the effectiveness of a human operator paired with a decision support system, it is necessary to complement current testing practices addressing software validation, human performance, and usability. Decision Centered Testing (DCT) aims at testing the effectiveness of operators teamed with Decision Support Systems (DSS) in any challenging work domain. DCT is grounded in a Cognitive Systems Engineering (CSE) framework, where the concept of a joint cognitive system (JCS) is central. DCT aims at evaluating the decision-making effectiveness across identified 'error prone' regions in the JCS structure. A description of the DCT Methodology with an illustration taken from an initial application of the methodology is presented. In this application, insights from the DCT methodology enabled the definition of appropriate test metrics and the construction of unique test scenarios to exercise the decision-making effectiveness. From this application, it can be concluded that following the DCT Methodology facilitated the construction of an evaluation framework for assessing JCS net decision-making effectiveness.

The present study is about the effect of temporal uncertainty on the control of a dynamic task. Two types of temporal uncertainty are defined: Data Uncertainty (DU), the variability in temporal information, and Knowledge Uncertainty (KU), the complexity in the temporal structure of a situation. The effect of temporal data uncertainty on the control of a dynamic task with high knowledge temporal uncertainty is tested experimentally. Fifty-seven participants practiced the computerized game ‘Save the Whale’, with three levels of data uncertainty about the moment of occurrence of critical events, DU0, DU1 and DU2. Results show that performance is better in the DU0 than in the other two conditions, which do not differ from each other. The performance improves with practice at the same rate, regardless of the level of uncertainty. It is also shown that the control strategies reported by the participants become more variable with an increase in uncertainty. It is concluded that temporal data uncertainty does not...

Because of their intrinsic nature, it is fundamental to consider the temporal dimension when studying control in dynamic situations. However, the temporal aspect is often taken for granted and not accounted for in cognitive or control models. The present study aims to understand the role of temporal estimation in the control of a dynamic task, within the Contextual Control Model (COCOM). Particularly, the main objective is to evaluate how time pressure influences the estimation of available and required time. A dynamic situation, which includes two sub-tasks, the pursuit of a target and the avoidance of hostile contacts, is used. Results show that both available and required estimated times, as well as performance, decrease with increased time pressure. These findings suggest that when faced with a high level of time pressure, people adapt their strategies by giving up an offensive mode of control, in favor of a more defensive one, earlier in the game.

A temporal reproduction task is composed of two temporal estimation phases: encoding of the interval to be reproduced, followed by its reproduction. The effect of short-term memory processing on each of these phases was tested in two experiments. In Exp. 1, a memory set was presented, followed by two successive tones bounding the target interval to be reproduced. During the reproduction of the target interval, a probe was presented, and the subject ended the reproduction by pressing one of two keys, depending on the presence or absence of the probe in the memory set. In Exp. 2, probe recognition was required during the encoding of the interval to be reproduced. Whereas in Exp. 1 reproductions lengthened as a function of memory-set size, in Exp. 2 temporal reproductions decreased with set size. These results support attentional models of time estimation and suggest that short-term memory processing interrupts concurrent accumulation of temporal information.

Problematic command and control situations are often characterized with high levels of uncertainty and severe time constraints. In time compressed situations where only a limited number of information can be considered by the decision-maker, it becomes critical that the information available is the most relevant for taking action in that situation. This paper presents a Framework for the Analysis of Information Relevance (FAIR). The objective with this stepwise framework is to guide filtering and prioritization of information based on its level of relevance to the situation. The rationale is that with adequate filtering and prioritization processes, the decision-maker is left with only the most relevant information to act within a time-constrainted window of opportinity.

The prevalence of surveillance and information collection technologies provides decision-makers with greater volume and complexity of information to monitor and on which to base decisions than ever before. In this ever increasing dynamic and information rich environment, the role for decision support systems (DSS) to augment cognition and situation awareness (SA) is becoming crucial. However, unless a better understanding is gained of the factors that promote SA without interfering with other critical cognitive functions, the design and development of such technology may serve only to exacerbate rather than enhance the desired effect. The present study investigates how DSS designed to support particular aspects of SA may affect task performance. In the context of a functional computer-controlled simulation of single ship naval anti-air warfare, a baseline condition was compared to two conditions in which a DSS was integrated to the original interface to support different facets of SA. Participants in the two DSS conditions showed an increased SA level, as measured by the QUASA technique, compared to those in the control condition. Despite this benefit, the two DSS actually lead to a reduced performance, as indexed by defense effectiveness. These findings suggest that the benefits of DSS in terms of SA may be accompanied by an overhead with adverse effects on task performance, particularly in situations of high cognitive load and time constraints. This calls for more holistic evaluations of the cognitive impacts of decision support technologies and the development of methods to simultaneously address competing constraints when designing DSS.

Previous studies have shown that the effect of concurrent nontemporal processing on time estimation may vary depending on the level of difficulty of the nontemporal task. This is commonly interpreted within the context of so-called distraction/interruption models of temporal processing, which propose that as concurrent task difficulty or complexity is increased, temporal processing receives less attention. We hypothesize that the effect of nontemporal processing does not depend on the level of difficulty as such, but rather on the extent to which the concurrent nontemporal task specifically involves processing in short-term memory. Four experiments were run in which the short-term memory requirements of concurrent tasks were systematically varied, although all of the tasks were of comparable levels of difficulty. In the first experiment, the effect of memory search on simultaneous temporal productions was proportional to the number of items to search. As with reaction time, produced intervals were shown to increase linearly with the number of items in the memorized set. In Experiment 2, a visual search involving some load on short-term memory interfered in the same way with time production, although to a lesser extent. The last two experiments showed that performing attention-demanding visual search tasks that did not involve short-term memory did not lengthen simultaneously produced time intervals. This suggests that interference of nontemporal processing on time processing may not be a matter of nonspecific general purpose attentional resources, but rather of concurrent short-term-memory processing demands.

Resume La performance a une tache secondaire de frappe cadencee est couramment interpretee comme un indice de la charge de travail mental imposee par une tache primaire simultanee, l'augmentation de la moyenne ou de la variabilite des intervalles interfrappes etant associee a une augmentation de la charge mentale. Cette experience etudie la sensibilite de la frappe cadencee, a des intervalles interfrappes d'environ deux secondes, aux demandes de ressources dans une prospection mnemonique. Un ensemble de trois chiffres etait memorise avant une serie de frappes. Apres chaque frappe, une sonde, chiffre ou lettre, etait presentee; la position de la frappe suivante etait determinee par le fait que la sonde etait membre ou non de l'ensemble memorise. L'hypothese est que la demande de ressources varie selon la sonde : une sonde - chiffre suscite un processus de comparaison plus long que celui d'une sonde - lettre. Les resultats montrent que la presentation d'une sonde - chiffre negative, c'est - a - dire n'appartenant pas a l'ensemble memorise, induit des intervalles interfrappes plus longs que la presentation d'une sonde - lettre negative. De plus, les intervalles tendent a etre plus longs lorsque la sonde - chiffre est negative que lorsqu'elle est positive. Ces donnees confirment la sensibilite de la frappe cadencee a la charge posee par une prospection mnemonique. L'evolution de la performance avec la pratique permet toutefois de constater que l'utilisation de strategies peut masquer la sensibilite de la frappe cadencee.Abstract When executed concurrently with a primary task, finger tapping performance is commonly interpreted as an indication of the primary task mental workload. Higher load during tapping induces an increase in mean or variability of intertap intervals. Finger tapping sensitivity was tested with series of 13 taps at a tapping rate of one tap every two seconds. Concurrent primary task required subjects to search for a target item, presented after each tap, in a three digit memory set memorized before each series. Processing load was varied by including letter targets amongst positive and negative digit targets. Letter target recognition should require less processing than digit recognition. Results show mean intertap intervals for letter targets to be shorter than for negative digit targets. Furthermore, recognition of negative digit targets induces a longer mean intertap interval than positive targets. These data suggest that continuous finger tapping is a sensitive index of the mental workload originating from working memory processing requirements. However, analysis of practice data show that development of strategies at performing the dual task may mask the sensitivity of the finger tapping task.L'operateur humain possede une capacite limitee de traiter l'information. La charge de travail mental (CTM) fait reference a cette portion de la capacite limitee de traitement requise pour effectuer une tache particuliere (O'Donnell & Eggemeier, 1986). La technique de tache secondaire compte parmi les principales mesures de charge mentale. Dans cette technique, la CTM exigee par une tache dite primaire est inferee a partir de la performance a une tache secondaire executee en meme temps que cette tache primaire. La presente etude analyse une tache secondaire couramment utilisee, la frappe cadencee. Developpee a l'origine par Michon (1966), la technique de frappe cadencee a ete appliquee avec un certain succes dans l'analyse de taches en situation appliquee, par exemple de conduite automobile (Wildervanck, Mulder & Michon, 1977; Rousseau, Moreau, Lambert, Pitre & Arsenault, 1985), de pilotage simule d'avion (Casali & Wierville, 1983), et d'edition de texte informatisee (Harvey & Rousseau, 1990).Dans cette tache, les sujets doivent produire une serie d'actions motrices simples, par exemple, une succession de frappes du doigt. Ces frappes doivent etre effectuees le plus regulierement possible, a un tempo determine par l'experimentateur. …

In a stop-reaction-time (stop-RT) task, a subject is presented with a regular, isochronous sequence of brief signals separated by a constant time interval, or stimulus onset asynchrony (SOA). His/her task is to press a response key as fast as possible when the sequence stops. As the sequence unfolds, an internal representation of the SOA duration builds up. Stop-RT is assumed to be triggered when an internal clock, operating as an "alarm clock," reaches a time criterion. Criterion setting is contingent upon variability in the SOA's internal representation. In Experiment 1A, stop-RT was measured for isochronous sequences of brief tones, light flashes, and also sequences of tones and flashes presented in regular alternation (tone-light-tone ...). Stop-RT was a linear function of SOA duration (ranging from 250 to 1,000 msec), regardless of modality, supporting a "central-clock" hypothesis. On the other and, taken together, the results of Experiments 1A, 1B, 2, and 3 suggest that no internal representation of the bimodal (tone-light) SOA of alternating sequences builds up. Indeed, an alternating sequence is physically equivalent to two interlaced isochronous subsequences, one auditory and one visual. So, two internal representations, one for the auditory (tone-tone) and one for the visual (light-light) SOA, could build up, and two time criteria running "in parallel" could thus support stop-RT. To provide a critical test of parallel timing, stop-RT was measured for bimodal 5:3 polyrhythms formed by the superposition of auditory and visual isochronous sequences that had different SOA durations (Experiment 4). Parallel timing accounted for a large proportion of variance in polyrhythmic stop-RT data. Overall findings can be accounted for by assuming a functional architecture of an internal clock in which pulses emitted by a central pacemaker are available in parallel with two modality-specific switch-accumulator "timing modules."

Cats (Felis catus) find an object when it is visibly moved behind a succession of screens. However, when the object is moved behind a container and is invisibly transferred from the container to the back of a screen, cats try to find the object at or near the container rather than at the true hiding place. Four experiments were conducted to study search behavior and working memory in visible and invisible displacement tests of object permanence. Experiment 1 compared performance in single and in double visible displacement trials. Experiment 2 analyzed search behavior in invisible displacement tests and in analogs using a transparent container. Experiments 3 and 4 tested predictions made from Experiment 1 and 2 in a new situation of object permanence. Results showed that only the position changes that cats have directly perceived are encoded and activated in working memory, because they are unable to represent or infer invisible movements.

Through the functionalization strategy of multi-walled carbon nanotubes (MWCNTs) with polyvinyl acetate (PVAc), dampening material for acoustic devices was sought. In this paper, we investigated the effect of polymer grafting of MWCNTs on the frequency response based on a mechanistic basis. We have found that vibration reduction ability of the MWCNTs incoporated polymer has a maximum increase of 70% compared with pure polymer. Composites with pristine MWCNTs and polymer grafted MWCNTs were found to exhibit similar dynamic mechanical behavior in the frequency above 1000 Hz.

Three experiments address the cause of the different performance levels-found in time discrimination of empty intervals with durations near 250 msec. Performance differed according to the kind of sensory modality that marked the intervals. With a procedure in which the type of marker was randomized from trial to trial, it was shown that variability of discrimination judgments could not be attributed entirely to the variability of the criterion on which-a judgment was based. Such a randomization slightly affects discrimination but provokes a reorganization related to marker conditions of the probabilities of judging an interval to be short or long. Moreover, it was shown that within intramodal conditions, physical characteristics of markers influence the discrimination performances. To account for the results generated with different marker-type intervals at 250 msec, we propose that two types of processor may be involved in duration discrimination: one is specifically related to a given sensory modality, whereas the other is aspecific and responsible for discrimination of intermodal intervals.

In a series of systematic studies, Massaro and his colleagues (Massaro, 1970, 1975; Massaro, Cohen, & Idson, 1976) have demonstrated that the judgment about the pitch, timbre, or lateralization of an auditory stimulus can be influenced by following the stimulus to be identified (the test stimulus) by a second auditory stimulus (the mask). Correct recognition improves as the interval between the offset of the test stimulus and the onset of the mask is increased to about 250 msec. The data from these recognition masking studies form the foundation for Massaro's (1975) theory for auditory recognition. Massaro (1972b) suggested that the recognition masking paradigm might also prove to be useful in understanding the manner in which temporal information is processed, and recently he has used this paradigm to investigate the perceived duration of brief auditory events (Massaro & Idson, 1976). On each trial, one of two auditory test stimuli which differed induration was followed, after a variable silent interval, by a second auditory stimulus, the mask. The subject's task was to identify the task stimulus as short or long. The durations of the test stimuli arid the masks were brief-less than 110 msec. The data clearly indicate that performance was influenced by the duration of the test stimulus, the duration of the silent intertone interval, and the duration of the mask. For the purpose of the present note, the important finding was that duration discrimination improved as the interval between the offset of the test stimulus and the onset of the mask was increased to about 165 msec. Cantor and Thomas (1976) have reported a duration masking study using visual stimuli. The duration of the test stimulus was either 20 or 50 msec, the duration of the mask was 500 msec, and the test stimulus-offset/mask-onset interval varied from

In 1973, Rousseau and Kristofferson reported that short empty intermodal time intervals marked by a light flash and a brief tone were poorly discriminated by subjects, and that AT,5 was constant over a large range of durations. It led them to suggest that short intramodal empty intervals, marked by stimuli from the same sensory modality, might be handled by a “more efficient mechanism” to which intermodal intervals would not have access. Unfortunately, their study lacked the basic evidence needed to make a strong statement: no direct comparison between inter- and intramodal duration discrimination and no within-subject discrimination function were available. To clarify these two issues, three experiments were performed. The data indicate that intermodal time intervals are discriminated more poorly than intramodal ones, and that intermodal duration discrimination functions follow Weber’s law. Analysis of data from different experiments lead to the conclusion that inter- and intramodal intervals are timed by a common timekeeper and that intermodal intervals induce a large noise component in the timekeeping operation.

The purpose of this study was controlling the facilitatory effect on target detection due to the distance between inducing fields and the duration of target presentation. The experiment was carried on with 2 experienced observers. It appeared that such an effect does exist for a distance of 1° 3′ between the active fields. However, it seems to be strongly related to a critical range of duration of target presentation.

Rousseau R. Le palmier à huile au Sénégal. In: L'information géographique, volume 14, n°4, 1950. pp. 141-148.

Rousseau R. Évolution de la population en Grèce. In: L'information géographique, volume 26, n°5, 1962. pp. 209-215.

Rousseau R. La population de la Turquie en 1960. In: L'information géographique, volume 27, n°4, 1963. pp. 154-158.

Rousseau R. Les noms des lieux habités en France (suite). In: L'information géographique, volume 24, n°5, 1960. pp. 218-227.

Rousseau R. La période des cultures et des récoltes au Sénégal. In: L'information géographique, volume 18, n°2, 1954. pp. 68-70.

The influence of cognitive processing on time estimation was investigated. A temporal-interval production and memory-search dual task was devised so that some operations needed by the search took place during the time interval. Subjects were required to produce time intervals concurrently with a memory-search task similar to Sternberg's (1966). On the average, duration increased in proportion to the number of elements in the positive set. In general, temporal-production duration displayed the features previously observed, with speeded responses in memory-search tasks. The additive effect of memory scanning on time estimation made possible an interpretation involving inhibition of timing during concurrent processing in short-term memory. This concurrent processing situation appears to be a fruitful procedure for the study of the interaction between time estimation and cognitive processes. However, since a methodological feature of the search task could favor a successive processing strategy, the possibility that subjects performed the time production and the item-recognition tasks successively makes a conclusive interpretation difficult.

Rousseau Robert. Le canal Rhin-Danube. In: Annales de Géographie, t. 30, n°164, 1921. pp. 141-144.

Rousseau R. La population du Sénégal d'après le recensement de 1936. In: L'information géographique, volume 2, n°1, 1937. pp. 16-17.

Rousseau R. Les Suisses dans le canton de St-Julien-en-Genevois. Etude statistique. In: Bulletin de l'Association de géographes français, N°231-232, 30e année, Janvier-février 1953. pp. 38-51.

Rousseau R. Les diagrammes climatiques. In: L'information geographique, volume 26, n°1, 1962. pp. 35-39.

Rousseau R. Les noms de lieux habités en France. In: L'information géographique, volume 24, n°4, 1960. pp. 171-179.

À partir des pratiques de l’organisme communautaire Action Séro Zéro, cet article propose une réflexion sur le travail de proximité à l’égard d’enjeux reliés à la vie privée. Sont prises en considération des conceptions de la prévention du VIH qui mettent en lumière les risques d’ingérence dans la vie privée. Le contexte des milieux de socialisation fréquentés par les hommes gais et bisexuels est ensuite présenté, ainsi que des exemples du travail de proximité réalisé dans ces milieux. Dans ces exemples d’intervention de proximité, le risque d’outrepasser les limites du respect de la vie privée des individus serait contrebalancé par l’utilisation de méthodes dialogiques et participatives, ainsi que par l’ancrage dans les démarches de démocratisation d’accès dans les services de santé., This article critically reflects on issues related to personal privacy raised by outreach work. It draws on examples of intervention practices used at Action Séro Zéro, a community-based organization. Theoretical conceptions of HIV prevention work are examined with regards to the possibility outreach work of this type leads to an infringement on private life. Social settings popular among gay and bisexual men are then considered alongside examples of outreach work undertaken in these settings. In these examples, the risk that outreach work might fail to respect personal privacy is countered by the dialogical and participative methods used within this work and its grounding in efforts to democratize access to health services.

Difference thresholds for the duration of empty time intervals marked off by a light flash and a tone burst were determined at base durations extending from 100 to 2000 msec. Threshold is shown not to be a function of base duration. For base durations in the lower part of the range studied, threshold is much higher than that usually obtained in experiments done under other conditions.

After performing barium enemas, we have noted repeatedly the presence of feces in residual barium sulfate. The plastic tubing used in preparatory enemas, therefore, was closely observed, and in many cases feces and mucus were seen to pass from the rectum into the tube for varying distances, sometimes all the way into the enema can. Since for the next patient only the enema tip was discarded and replaced, it became obvious that we were contaminating some patients with rectal contents from patients previously examined. Radiologists in different parts of the country were queried about their methods of preventing cross-contamination of patients. Their replies indicated that in the majority of institutions and private offices the rectal tubes are changed and either washed, discarded, or sterilized. More barium sulfate is added to the residue for the examination of the next patient. Only occasionally is the barium sulfate discarded and the can and