Overspecification and incremental referential processing: An eye-tracking study

Using eye-tracking, we examined if over-specification hinders or facilitates referent selection, and the extent to which this depends on the properties of the attribute mentioned in the referring expressions and the underpinning processing mode. Following spoken instructions, participants selected the referent in a visual display while their eye movements were monitored. The referring expressions were presented either simultaneously with the displays, so the attributes could be incrementally processed in sequence, or before the display presentation, so the attributes could be processed in parallel from the outset of search. Experiment 1 showed that when the attributes were processed incrementally, how quickly an earlier-mentioned attribute discriminated determined whether a late-mentioned, over-specified attribute contributed to discrimination: When color was mentioned first and is fully discriminating, the referent was selected fast regardless of the second-mentioned pattern, whereas when pattern was mentioned first and is fully discriminating, the second-mentioned color facilitated discrimination. Experiment 2 found that under incremental processing, color mention after a fully discriminating pattern increased fixations but delayed referent selection relative to a pattern-only description; under parallel processing, however, color mention immediately eliminated alternatives and sped up referent selection. Experiment 3 showed that pattern mention after a fully discriminating color delayed referent selection and tended to reduce fixations relative to a color-only description in both processing modes. Hence, additional attributes can speed up referent selection but only when they can discriminate much faster than alternative attributes mentioned in a more concise description, and critically, when they can be used early for referent search.

Pattern Separation Contributes to Categorical Face Perception

Traditionally considered a memory structure, the hippocampus has been shown to contribute to non-memory functions, from perception to language. Recent evidence suggests that the ability to differentiate highly confusable faces could involve pattern separation, a mnemonic process mediated by the hippocampal dentate gyrus (DG). Hippocampal involvement, however, may depend on existing face memories. To investigate these possibilities, we tested BL, a rare individual with bilateral lesions selective to the DG, and healthy controls. Both were administered morphed images of famous and nonfamous faces in a categorical perception (CP) identification and discrimination experiment. All participants exhibited nonlinear identification of famous faces with a midpoint category boundary. Controls identified newly learned nonfamous faces with lesser fidelity, while BL showed a notable shift in category boundary. When discriminating face pairs, controls showed typical CP effects of better between-category than within-category discrimination — but only for famous faces. BL showed extreme within-category “compression,” reflecting his tendency to pattern complete following suboptimal pattern separation. We provide the first evidence that pattern separation contributes to CP of faces.

On Taiwanese pupils’ ability to differentiate between English /l/ and /r/: A study of L1/L2 cross-language effects

Students in South East Asia often struggle with English /l/ and /r/. This study therefore set out to examine how Taiwanese pupils’ perception of these sounds is influenced by cross-language effects. Most Taiwanese students have Mandarin as L1 and Taiwanese as L2 or vice versa, and English as L3. A same–different discrimination experiment was conducted to measure pupils’ ability to discriminate between phonetically close English /r/ and /l/ and Mandarin /ʐ / and /l/. The results show that L1-Mandarin pupils discriminate both the English consonant contrast and the Mandarin consonant contrast better than L1-Taiwanese pupils. Discrimination difficulty may be higher if two members of a contrast are perceived as belonging to a single L1 category.

Estimating a User's Internal State before the First Input Utterance

This paper describes a method for estimating the internal state of a user of a spoken dialog system before his/her first input utterance. When actually using a dialog-based system, the user is often perplexed by the prompt. A typical system provides more detailed information to a user who is taking time to make an input utterance, but such assistance is nuisance if the user is merely considering how to answer the prompt. To respond appropriately, the spoken dialog system should be able to consider the user’s internal state before the user’s input. Conventional studies on user modeling have focused on the linguistic information of the utterance for estimating the user’s internal state, but this approach cannot estimate the user’s state until the end of the user’s first utterance. Therefore, we focused on the user’s nonverbal output such as fillers, silence, or head-moving until the beginning of the input utterance. The experimental data was collected on a Wizard of Oz basis, and the labels were decided by five evaluators. Finally, we conducted a discrimination experiment with the trained user model using combined features. As a three-class discrimination result, we obtained about 85% accuracy in an open test.

Comparisons of Two Variants of the Method of Constant Stimuli for Estimating Difference Thresholds

The two-alternative forced-choice (2AFC) and the reminder tasks are variants of the method of constant stimuli. One or the other task is usually employed for estimating the difference limen (DL) in psychophysical research. Lapid, Ulrich, and Rammsayer (2008) found that the 2AFC task yields larger DLs than the reminder task for duration discrimination judgments. The results of the present paper confirm that this discrepancy also generalizes to discrimination judgments about nontemporal, visual information (Experiment 1: Random dot pattern discrimination; Experiment 2: Line-length discrimination). It is argued that this discrepancy is related to the presentation order of the standard and the comparison stimulus.