Transposition Effects in an Aksharic Writing System: The Case of Hindi.

We tested for transposition effects (TEs) in Hindi (a Modern Indo-Aryan language) using unprimed lexical decision. TEs are defined as less accurate and slower responses to transposed-nonwords (e.g., , formed from base-word ) than corresponding replaced-nonwords (e.g., ). In Hindi's orthography, letters map transparently to phonemes (except schwa), but the letters are arranged into "akshars," (n]V>) which encode open syllables. This formal characteristic makes Hindi's orthography typologically "aksharic." We used TEs to determine whether the orthography's typological units, letters and akshars, are also functional units for readers. We conducted three visual word recognition experiments with adult readers whose native language was Hindi. In Experiment 1, we found TEs for consonant () and matra (, a vowel diacritic) letters, using different stimulus sets for each type of transposition. In the next two experiments, we used the same base words to form all of the transposed and replaced items. In Experiment 2, we replicated the findings of Experiment 1 in a different stimulus set; additionally, we found TEs for transpositions between a letter and a akshar. In Experiment 3, we replicated results of the first two experiments by finding TEs for both consonants and matras in another stimulus set; additionally, we found similar TEs for akshars. These results show that and letters are functional units for Hindi readers; the transposition results for akshars are tentative. TEs for letters show that the aksharic grouping of letters does not prevent readers from decoding the constituent letters of akshars. Hindi is read alphabetically.

Desktop VR Is Better Than Non-ambulatory HMD VR for Spatial Learning.

Use of virtual reality (VR) technology is proliferating for designing and upgrading entertainment devices, and creating virtual environments that could be used for research and training. VR is becoming a strong research tool by providing a tighter control on the experimental environment and by allowing almost limitless possibilities of creating ecologically valid stimuli. However, the enhanced fidelity between the real and virtual worlds that VR provides does not always benefit human performance. For a better understanding, and increasing VR's usability, we need to identify the relevant constituent components of immersive technologies, and differentiate their roles, for example, how visual and interaction fidelity differentially improves human performance. We conducted an experiment to examine how two common VR display modes, head mounted display (HMD) and desktop (DT), would affect spatial learning when we restrict ambulatory locomotion in HMD. This manipulation allowed examining the role of varying visual fidelity with low interaction fidelity. We used a between-group design with 40 naïve participants. They explored a virtual environment and later drew its sketch-map. Our results showed participants spent more time and perceived less motion-sickness and task effort using desktop than HMD VR. With reduced interaction fidelity, the high visual fidelity of HMD as compared to desktop resulted in similar or poorer performance on different spatial learning tasks after accounting for motion-sickness and workload effort. Participants were better in recalling spatial components related to junction and cyclic order of the navigated virtual space in desktop vs. HMD VR, and performed equally well on components related to street segments and object associations. We explain these results in terms of deficient idiothetic information in non-ambulatory HMD and lesser sensory conflicts in desktop mode. Overall, our results highlight the differential effect of visual vs. interaction fidelity on human performance based on using immersive technologies, how such an effect depends on the nature of cognitive and functional behavior users employ, and the higher usability of traditional desktop VR. These results are relevant for developing customized and sustainable virtual reality based human-computer interactions.

On the Interaction of Letter Transpositions and Morphemic Boundaries.

Investigations of the impact of morphemic boundaries on transposed-letter priming effects have yielded conflicting results. Five masked priming lexical decision experiments were conducted to examine the interaction of letter transpositions and morphemic boundaries with English suffixed derivations. Experiments 1-3 found that responses to monomorphemic target words (e.g., SPEAK) were facilitated to the same extent by morphologically related primes containing letter transpositions that did (SPEAEKR) or did not (SPEKAER) cross a morphemic boundary. This pattern was also observed in Experiments 4 and 5, in which the targets (e.g. SPEAKER) were the base forms of the transposed-letter primes. Thus, in these experiments the influence of the morphological structure of a transposed-letter prime did not depend on whether the letter transposition crossed a morphological boundary.