Designing interactive consumer products: utility of paper prototypes and effectiveness of enhanced control labelling.

The studies reported here examined differences in user behaviour when presented with a low-fidelity paper prototype compared to fully operational product, and evaluated the effectiveness of different types of enhanced labelling of controls. In the first study with a paper prototype, 30 users of high-pressure washers were asked to choose the settings of the temperature control for different cleaning objects, comparing standard with information-enriched control labelling. In the second study, 34 users operated a real high-pressure washer with different forms of control labelling. The results of both studies provided evidence for some benefits of an information-enriched control labelling over traditional temperature-centred controls labelling. Furthermore, a comparative analysis of the data of the two studies suggested that low-fidelity paper prototypes may have to be used with caution. Therefore, designers need to be aware that the behavioural effects induced by different design modifications may be overestimated when using paper prototypes. The implications of the findings are discussed within the framework of an enlarged concept of fidelity.

Cognitive diversity and team performance in a complex multiple task environment.

This article examines the multiple effects of cognitive diversity in teams operating complex human-machine-systems. The study employed a PC-based multiple-task environment, called the Cabin Air Management System, which models a process control task in the operational context of a spacecraft's life support system. Two types of cognitive diversity were examined: system understanding and team specialization. System understanding referred to the depth of understanding team members were given during training (low-level procedure-oriented vs. high level knowledge-oriented training). Team specialization referred to the degree to which knowledge about system fault scenarios was distributed between team members (specialized vs. non-specialized). A total of 72 participants took part in the study. After having received 4.5 h of training on an individual basis, participants completed a 1-h experimental session, in which they worked in two-person teams on a series of fault scenarios of varying difficulty. Measures were taken of primary and secondary task performance, system intervention and information sampling strategies, system knowledge, subjective operator state, communication patterns and conflict. The results provided evidence for the benefits of cognitive diversity with regard to system understanding. This manifested itself in better primary task performance and more efficient manual system control. No advantages were found for cognitive diversity with regard to specialization. There was no effect of cognitive diversity on intra-team conflict, with conflict levels generally being very low. The article concludes with a discussion of the implications of the findings for the engineering of cognitive diversity in teams operating complex human-machine-systems.

Syntheses, crystal structures, and density functional theory calculations of the closo-[1-M(CO)(3)(eta(4)-E(9))](4-) (E = Sn, Pb; M = Mo, W) cluster anions and solution NMR spectroscopic characterization of [1-M(CO)(3)(eta(4)-Sn(9))](4-) (M = Cr, Mo, W).

The closo-[1-M(CO)(3)(eta(4)-E(9))](4-) (E = Sn, Pb; M = Mo, W) anions have been obtained by extracting the binary alloys KSn(2.05) and KPb(2.26) in ethylenediamine (en) in the presence of 2,2,2-crypt or in liquid NH(3) followed by reaction with M(CO)(3).mes (M = Mo, W) or Cr(CO)(3).tol in en or liquid NH(3) solution. Crystallization of the molybdenum and tungsten salts was induced by vapor diffusion of tetrahydrofuran into the en solutions. The salts [2,2,2-crypt-K](4)[1-M(CO)(3)(eta(4)-Sn(9))].en (M = Mo, W) crystallize in the triclinic system, space group P1, Z = 4, a = 16.187(3) A, b = 25.832(4) A, c = 29.855(5) A, alpha = 111.46(1) degrees, beta = 102.84(2) degrees, gamma = 92.87(2) degrees at -95 degrees C (M = Mo) and a = 17.018(3) A, b = 27.057(5) A, c = 28.298(6) A, alpha = 66.42(3) degrees, beta = 76.72(3) degrees, gamma = 87.27(3) degrees at 20 degrees C (M = W). The salts (CO)(3)M(en)(2)[2,2,2-crypt-K](4)[1-M(CO)(3)(eta(4)-Pb(9))].2.5en (M = Mo, W) crystallize in the triclinic system, space group P1, Z = 2, a = 16.319(3) A, b = 17.078(3) A, c = 24.827(5) A, alpha = 71.82(3) degrees, beta = 83.01(3) degrees, gamma = 81.73(3) degrees at -133 degrees C (M = Mo) and a = 16.283(4) A, b = 17.094(3) A, c = 24.872(6) A, alpha = 71.62(2) degrees, beta = 82.91(2) degrees, gamma = 81.35(2) degrees at -153 degrees C (M = W). The [1-M(CO)(3)(eta(4)-Sn(9))](4-) anions were also characterized in liquid NH(3) solution by (119)Sn, (117)Sn, and (95)Mo NMR spectroscopy. Unlike their fluxional precursor, nido-Sn(9)(4-), NMR studies show that the [1-M(CO)(3)(eta(4)-Sn(9))](4-) anions are rigid on the NMR time scale. All possible inter- and intraenvironmental couplings, J((119,117)Sn-(119,117)Sn), J((119,117)Sn-(183)W), and one J((119,117)Sn-(95)Mo) coupling, have been observed and assigned. Complete spin-spin coupling constant assignments were achieved by detailed analyses and simulations of all spin multiplets that comprise the (119)Sn and (117)Sn NMR spectra and that arise from natural abundance tin isotopomer distributions and from natural abundance (183)W, in the case of [1-W(CO)(3)(eta(4)-Sn(9))](4-). Both the solid state and solution structures of the [1-M(CO)(3)(eta(4)-Sn(9))](4-) anions are based on a closo-bicapped square antiprismatic structure in which the transition metal occupies a cap position. The cluster structures are consistent with Wade's rules for 22 (2n + 2) skeletal electron systems. Electron structure calculations at the density functional theory (DFT) level provide fully optimized geometries that are in agreement with the experimental structures. Complete assignment of the NMR spectra was also aided by GIAO calculations. The calculated vibrational frequencies of the E(9)(4-) and [1-M(CO)(3)(eta(4)-E(9))](4-) anions are also reported and are used to assign the solid-state vibrational spectra of the [1-M(CO)(3)(eta(4)-E(9))](4-) anions.