Two experiments were performed to investigate the buildup of repetition priming in a lexical decision task with repeated presentations and its decline over the course of 2 months. Priming was found to accumulate as a power function of presentations and to decline as a power function oftime. Accuracy measures indicated that the loss rate of priming was unaffected by the amount of initial priming. Response time measures indicated the same result when the experiments were analyzed separately; however, when the data were combined, increased initial priming was associated with greater losses in priming over time. The data were interpreted in terms of automaticity, and the power function decline in priming was taken as support for memory-based models of automaticity. Possible ways to incorporate forgetting into memory-based theories of automaticity are discussed. 611Repetition priming is the benefit accrued to the processing of a unit of information as a result of its having been encountered previously, with the benefit usually measured in terms of faster response time or greater accuracy. Duration is a fundamental aspect of the phenomenon. In the case of repetition priming in lexical decision tasks, for example, the recognition of a letter string as a word implies that the word has been seen in the past. For the concept of repetition priming to have any meaning, priming must be temporary. Understanding the transitory nature of this repetition effect is central to the understanding of repetition priming.Sloman, Hayman, Ohta, Law, and Tulving (1988) reviewed several studies on the duration of repetition priming over relatively short intervals and then conducted a series of experiments in which they measured priming shortly after study and 1 week after study. These experiments consistently indicated that the repetition effect declined quickly in the first few minutes after training, and that there was relatively little further loss between a few minutes and a week after training. Salasoo, Shiffrin, and Feustel (1985) used a different technique, extended practice, to look at priming over a longer interval. In a series of word identification experiments, they found that repetition priming could still be detected 1 year after training. They also found that repetition priming was cumulative; identification thresholds decreased continuously over 30 presentations.These two studies suggest further questions. Although Salasoo et al. (1985) showed that priming increased with Correspondence should be addressed to S. C. Grant, Life Sciences Division, Scarborough Campus, University of Toronto, 1265 Military Trail, Scarborough, ON, Canada MIC IA4 (e-mail: grant@lake.scar. utoronto.ca).increased numbers of repetitions and that the priming could be retained for a year, they did not explore the loss of priming as a functionof the number of repetitions. After examining performance at two retention intervals, Sloman et al. (1988) concluded that the loss of priming slowed after the first few minutes following training. They compared the c...

Users immersed in virtual environments (VEs) are prone to disorientation and have difficulty transferring spatial knowledge to the real world. A single experiment investigated the contribution of inadequate proprioception to this problem by providing participants with interfaces to a virtual environment that either did (a walking interface) or did not (a joystick) afford proprioceptive feedback similar to that obtained during real walking. The 2 groups explored a large, complex building using a low-resolution head-mounted display. Later, their navigational abilities within the actual building were compared with those of control groups who either studied a map of the building, walked through the real building, or received no prior training. The walking interface conveyed no benefit on an orientation task performed during training in the VE, but it did benefit participants when they tried to find objects in the real world. Actual or potential applications include simulations of environments that are normally explored on foot but cannot be readily visited, such as infantry battlefields and facilities contaminated with chemical, biological, or radiological materials.

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~~~ The U.S. Army is using virtual simulations for mission planning, training, rehearsal, and concept development Virtual environment (VE) technology can provide simulated real world activities for dismounted soldiers. One issue in the use of distributed simulations is whether team members learn, perform, and transfer their skills in distributed situations in the same ways as individuals in local situations. In this experiment, local and distributed teams completed a series of mission rehearsals in a VE over two days. Eighteen, two-person teams of college students performed synthetic tasks representative of tasks performed by police, emergency response, and military teams. All participants were trained to criterion in a VE before being assigned to a team. Biographical information and subjective self-report questionnaires were administered before, during, and after training and mission sessions. Local teams interacted face-to-face between mission rehearsal sessions, while distributed teams only interacted by phone during the after action review session following each mission. Local teams performed significantly better man distributed teams on several collective task measures over the repeated missions. Simulator sickness and presence during the mission rehearsals were also investigated.