Eye Tracking the Feedback Assigned to Undergraduate Students in a Digital Assessment Game.

High-quality feedback exerts a crucial influence on learning new skills and it is one of the most common psychological interventions. However, knowing how to deliver feedback effectively is challenging for educators in both traditional and online classroom environments. This study uses psychophysiological methodology to investigate attention allocation to different feedback valences (i.e., positive and negative feedback), as the eye tracker provides accurate information about individuals' locus of attention when they process feedback. We collected learning analytics via a behavioral assessment game and eye-movement measures via an eye tracker to infer undergraduate students' cognitive processing of feedback that is assigned to them after completing a task. The eye movements of n = 30 undergraduates at a university in Western Canada were tracked by the EyeLink 1000 Plus eye tracker while they played Posterlet, a digital game-based assessment. In Posterlet, students designed three posters and received critical (negative) or confirmatory (positive) feedback from virtual characters in the game after completing each poster. Analyses showed that, overall, students attended to critical feedback more than to confirmatory feedback, as measured by the time spent on feedback in total, per word, and per letter, and by the number of feedback fixations and revisits. However, there was no difference in dwell time between valences prior to any feedback revisits, suggesting that returning to read critical feedback more often than confirmatory feedback accounts for the overall dwell time difference between valences when feedback is assigned to students. The study summarizes the eye movement record on critical and confirmatory feedback, respectively. Implications of this research include enhancing our understanding of the differential temporal cognitive processing of feedback valences that may ultimately improve the delivery of feedback.

Mercury in the Arctic atmosphere: an analysis of eight years of measurements of GEM at Alert (Canada) and a comparison with observations at Amderma (Russia) and Kuujjuarapik (Canada).

Eight years of gaseous elemental mercury (GEM) concentration measurements from Alert, Nunavut, Canada (between 1995 and 2002) is presented. The annual time series shows a distinct repeating seasonal pattern with an overall annual median concentration for this time period of 1.58 (S.D.=0.04 ng m(-3)). Strong seasonal variation was observed throughout the years with springtime displaying strong variability in the GEM and overall lower median concentrations due to the so-called mercury depletion events (MDEs). Summer concentrations are higher than the annual average and show a decrease in variability. Fall and winter concentrations are distributed around the annual median concentrations and show little variability. The relationship between the springtime depression and the summer increase shows a change in the behaviour of mercury between 1995 and 2002. Preliminary results suggest that during this period an increasing amount of the mercury lost from the atmosphere in the spring is not returned to atmosphere in summer. A comparison of GEM concentration data from three sites--Alert (Canada), Amderma (Russia) and Kuujjuarapik (Canada)--demonstrated similar monthly distribution of GEM between Alert and Amderma, with the latter not showing as high summer concentrations. Monthly distribution of GEM at Kuujjuarapik varied considerably from the other two sites. MDEs were found to occur at each site in the spring yet displayed different characteristics. MDEs appear to start at Alert shortly after polar sunrise but in Amderma their initiation is delayed approximately 2 months following polar sunrise. MDEs occur in Kuujjuarapik in the springtime despite an incomplete development of the polar day-night cycle. In spring, as soon as air temperature attained temperatures consistently above 0 degrees C, MDEs ended immediately at all three sites. Continued studies into MDEs are warranted, but clearly an important component of future studies must focus on the origins of the variation of GEM behaviour at different sites.

Use of phycoerythrin and allophycocyanin for fluorescence resonance energy transfer analyzed by flow cytometry: advantages and limitations.

BACKGROUND: This study validates the use of phycoerythrin (PE) and allophycocyanin (APC) for fluorescence energy transfer (FRET) analyzed by flow cytometry. METHODS: FRET was detected when a pair of antibody conjugates directed against two noncompetitive epitopes on the same CD8alpha chain was used. FRET was also detected between antibody conjugate pairs specific for the two chains of the heterodimeric alpha (4)beta(1) integrin. Similarly, the association of T-cell receptor (TCR) with a soluble antigen ligand was detected by FRET when anti-TCR antibody and MHC class I/peptide complexes (<>) were used. RESULTS: FRET efficiency was always less than 10%, probably because of steric effects associated with the size and structure of PE and APC. Some suggestions are given to take into account this and other effects (e.g., donor and acceptor concentrations) for a better interpretation of FRET results obtained with this pair of fluorochromes. CONCLUSIONS: We conclude that FRET assays can be carried out easily with commercially available antibodies and flow cytometers to study arrays of multimolecular complexes.