Hemispheric involvement in shadowing vs. interpretation: a time-sharing study of simultaneous interpreters with matched bilingual and monolingual controls

A time-sharing study used shadowing and interpretation/paraphrasing tasks to evaluate lateralization in professional interpreters individually matched to bilingual and monolingual controls. A two-step multivariate general linear model procedure was used to determine lateralized effects and extent of disruption produced by the tasks. Results revealed the monolingual group to be left lateralized for both tasks, but the two bilingual groups were lateralized in the LH only for shadowing. The monolingual group was significantly different from the bilingual groups in the pattern of hand asymmetry for interpretation/paraphrasing. The findings replicate outcomes of prior repeated measures analysis of variance procedures on percentage of change scores. However, new information is added by the more refined analysis. The findings are also discussed in terms of previous laterality studies using similar tasks and subject samples.     

Naming multisyllabic words

The process of reading multisyllabic words aloud from print was examined in 4 experiments. Experiment 1 used multisyllabic words that vary in terms of the consistency of component spelling-sound correspondences. The stimuli were regular, regular inconsistent, and exception words analogous to the monosyllabic items used in previous studies. Both regular inconsistent and exception words produced longer naming latencies than regular words. In Experiment 2 these differences between word types were found to be limited to lower frequency items. Experiment 3 showed that effects of number of syllables on naming latency are also limited to lower frequency words when the stimulus display forced subjects to use syllabic units. Thus, frequency modulates the effects of two aspects of lexical structure-consistency of spelling-sound correspondences and number of syllables. The results suggest that the naming of multisyllabic words draws on some of the same knowledge representations and processes as monosyllabic words; however, naming does not require syllabic decomposition. The results are discussed in the context of current models of naming.     

Image statistics and the perception of apparent motion

The short- and long-range apparent motion processes are discussed in terms of the statistical properties of images. It is argued that the short-range process, exemplified by the random-dot kinematogram, is primarily sensitive to the dipole statistics, whereas the long-range process, exemplified by illusory occlusion, is treated by the visual system primarily in terms of the tripole and higher statistical correlation functions. The studies incorporate the balanced dot, which is a unique stimulus element that permits high pass filtering while preserving detailed positional information. Low spatial frequencies are shown to be critical for texture segregation in random-dot kinematograms, independent of the grain size or number density of texture elements. Illusory path perception in the long-range process is shown not to require low spatial frequencies, but is sensitive rather to global temporal phase coherency. These results are interpreted in terms of the respective roles of the power and phase spectra in perceptual organization. The construction of balanced dots is discussed in detail.     

Similarity neighborhoods of spoken two-syllable words: retroactive effects on multiple activation

This research examines the recognition of two-syllable spoken words and the means by which the auditory word recognition process deals with ambiguous stimulus information. The experiments reported here investigate the influence of individual syllables within two-syllable words on the recognition of each other. Specifically, perceptual identification of two-syllable words comprised of two monosyllabic words (spondees) was examined. Individual syllables within a spondee were characterized as either "easy" or "hard" depending on the syllable's neighborhood characteristics; an easy syllable was defined as a high-frequency word in a sparse neighborhood of low-frequency words, and a hard syllable as a low-frequency word in a high-density, high-frequency neighborhood. In Experiment 1, stimuli were created by splicing together recordings of the component syllables of the spondee, thus equating for syllable stress. Additional experiments tested the perceptual identification of naturally produced spondees, spliced nonwords, and monosyllables alone. Neighborhood structure had a strong effect on identification in all experiments. In addition, identification performance for spondees with a hard-easy syllable pattern was higher than for spondees with an easy-hard syllable pattern, indicating a primarily retroactive pattern of influence in spoken word recognition. Results strongly suggest that word recognition involves multiple activation and delayed commitment, thus ensuring accurate and efficient recognition.     

Stimulus repetition effects and the dimension-feature distinction in alternative targets

The negative repetition effect (NRE) refers to a poorer perception of the target in noise-same-as-target than in noise-alternative-target displays. Using the parenthesis as target and noise that are either identical or different in orientation, we tested predictions derived from a feature-specific inhibition model (Bjork & Murray, 1977) that explains the NRE as arising from inhibitory interactions among channels handling identical inputs. Contrary to our expectation of evidence for orientation-specific inhibition, a positive repetition effect (PRE) was observed. We also found a PRE for the dimension target sets whose stimuli differ only in orientation and an NRE for the feature target sets whose stimuli differ in the number of elements. Further experiments that systematically varied relationships between alternative targets indicate that these basic findings, termed the stimulus attributes effects, do not arise from pattern masking, perceptual strategies, or response bias.     

Moon illusion in pictures: a multimechanism approach

The existence of the moon illusion in pictorial representations was demonstrated in 6 experiments. Ss either judged the size of the moon in pictures, depicted as on the horizon or high in the sky, or drew horizon and elevated moons. The horizon moon was consistently judged to be larger than the elevated moon, independent of the angle at which the pictures are viewed. The distance paradox usually observed with the moon illusion (horizon moon apparently closer than the elevated moon) also exists in pictures. The magnitude of both size and distance effects depends on the salience of depicted depth cues. The pattern of results suggests that the moon illusion is caused by several interacting mechanisms and that use of pictorial stimuli may allow the separation of various cognitive from physiological contributions to the illusion.     

Cognition and metacognition at extreme altitudes on Mount Everest

The FACTRETRIEVAL2 test battery, which assesses both retrieval of general information from memory and metacognition about that retrieval, was administered to people before and after a recent expedition to Mount Everest and at extreme altitudes above 6,400 m (higher than any mountain in North America or Europe). The major findings were as follows: First, the same extreme altitudes already known to impair learning did not affect either accuracy or latency of retrieval, and this robustness of retrieval occurred for both recall and forced-choice recognition. Second, extreme altitude did affect metacognition: The climbers showed a decline in their feeling of knowing both while at extreme altitude and after returning to Kathmandu (i.e., both an effect and an aftereffect of extreme altitude). Third, extreme altitude had different effects than alcohol intoxication (previously assessed by Nelson. McSpadden, Fromme, & Marlatt, 1986). Alcohol intoxication affected retrieval without affecting metacognition, whereas extreme altitude affected metacognition without affecting retrieval; this different pattern for extreme altitude versus alcohol intoxication implies that (a) hypoxia does not always yield the same outcome as alcohol intoxication and (b) neither retrieval nor metacognition is strictly more sensitive than the other for detecting changes in independent variables.     

Role of fear in mediating shuttle escape learning deficit produced by inescapable shock

The relation between the shuttlebox escape deficit produced by prior inescapable shock (IS) and fear during shuttlebox testing as assessed by freezing was investigated in rats. IS rats learned to escape poorly and were more fearful than either escapably shocked subjects or controls, both before and after receiving shock in the shuttlebox. However, fear and poor escape performance did not covary with the manipulation of variables designed to modulate the amount of fear and the occurrence of the escape deficit. A 72-hr interval between IS and testing eliminated the escape deficit but did not reduce preshock freezing. Diazepam before testing reduced both preshock and postshock fear in the shuttlebox but had no effect on the escape deficit. Naltrexone had no effect on fear but eliminated the escape deficit. This independence of outcomes suggests that the shuttlebox escape deficit is not caused by high levels of fear in IS subjects.     

How to study the kinetic depth effect experimentally

Sperling, Landy, Dosher, and Perkins (1989) proposed an objective 3D shape identification task with 2D artifactual cues removed and with full feedback (FB) to the subjects to measure KDE and to circumvent algorithmically equivalent KDE-alternative computations and artifactual non-KDE processing. (1) The 2D velocity flow-field was necessary and sufficient for true KDE. (2) Only the first-order (Fourier-based) perceptual motion system could solve our task because the second-order (rectifying) system could not simultaneously process more than two locations. (3) To ensure first-order motion processing, KDE tasks must require simultaneous processing at more than two locations. (4) Practice with FB is essential to measure ultimate capacity (aptitude) and, thereby, to enable comparisons with ideal observers. Experiments without FB measure ecological achievement--the ability of subjects to extrapolate their past experience to the current stimuli.