The spatial attributes of stimulus frequency and their role in monaural localization of sound in the horizontal plane

Listeners, whose right ears were blocked, located low-intensity sounds originating from loudspeakers placed 15 deg apart along the horizontal plane on the side of the open, or functioning, ear. In Experiment 1, the stimuli consisted of noise bursts, 1.0 kHz wide and centered at 4.0 through 14.0 kHz in steps of .5 kHz. We found that the apparent location of the noise bursts was governed by their frequency composition. Specifically, as the center frequency was increased from 4.0 to about 8.0 kHz, the sound appeared to move away from the frontal sector and toward the side. This migration pattern of the apparent sound source was observed again when the center frequency was increased from 8.0 to about 12.0 kHz. Then, with center frequencies of 13.0 and 14.0 kHz, the sound appeared once more in front. We referred to this relation between frequency composition and apparent location in terms of spatial referent maps. In Experiment 2, we showed that localization was more proficient if the frequency content of the stimulus served to connect adjacent spatial referent maps rather than falling within a single map. By these means, we have further elucidated the spectral cues utilized in monaural localization of sound in the horizontal plane.     

Failures to find suppression of episodic memories in the think/no-think paradigm

Anderson and Green (2001) had subjects learn paired associates and then selectively suppress responses to some of them. They reported a decrease in final cued recall for responses that subjectshad been instructed not to think of and explained their data as resulting from cognitive suppression, a laboratory analog of repression. We report three experiments designed to replicate the suppression/repression results. After subjects learned a series of A-B word pairs (e.g., ordsea-roach), they were then asked to respond to some items and not to think of other items when shown their cues 1, 8, or 16times. During a final recall test, they were cued with either asame (direct)probe (ordeal-__) or a n independent(indirect) probe (insect-r__) . None of our experiments showed reliable suppression effects with either the same or independent-probe tests. Suppression is apparently not a robust experimental phenomenon in the think/no-think paradigm.     

The effects of attenuation of frequency segments on binaural localization of sound

Perceived location of tonal stimuli d narrow noise bands presented in two-dimensional space varies in an orderly manner with changes in stimulus frequency. Hence, frequency has a referent in space that is most apparent during monaural listening. The assumption underlying the present study is that maximum sound pressure level measured at the ear canal entrance for the various frequencies serves as a prominent spectral cue for their spatial referents. Even in binaural localization, location judgments in the vertical plane are strongly influenced by spatial referents. We measured sound pressure levels at the left ear canal entrance for 1.0-kHz-wide noise bands, centered from 4.0 kHz through 10.0 kHz, presented at locations from 60° through ?45° in the vertical plane; the horizontal plane coordinate was fixed at ?90°. On the basis of these measurements, we fabricated three different band-stop stimuli in which differently centered 2.0-kHz-wide frequency segments were filtered from a broadband noise. Unfiltered broadband noise served as the remaining stimulus. Localization accuracy differed significantly among stimulus conditions (p<.01). Where in the vertical plane most errors were made depended on which frequency segment was filtered from the broadband noise.     

Predicting response to anxiety management in patients with generalised anxiety disorders

This paper describes the analysis of predictive factors in a group of generally anxious patients treated with anxiety management. Evidence for three reliable predictors is presented. It is argued these reflect anxiety, demoralisation and depression. The same three variables contributed to prediction of outcome after treatment and 6 months later, and their pre-treatment values classified 80% of the patients correctly into good or poor responders. Lower initial levels of anxiety and demoralisation together with higher depression rated by the assessor predicted a better outcome. Predictions were more accurate for patients with a mild degree of depression than for those who were not depressed.     

On the Problem of Two-Dimensional Error Scores: Measures and Analyses of Accuracy,Bias, and Consistency

Describing and analyzing error for one-dimensional performance tasks is fairly straightforward, but suggestions for describing and analyzing error for two-dimensional performance tasks (e.g., marksmanship) are quite problematic. Specifically, imposing an arbitrary axis onto the two-dimensional work space, along which traditional one-dimensional measures can be computed and analyzed, yields measures of accuracy, bias, and consistency that are entirely dependent upon the choice of axis. The present contribution offers new measures and methods for describing and analyzing data from two-dimensional performances. Unlike the resu1ts from previous suggestions, the approaches described herein yield results that are completely independent of the axes used to quantify the individual two-dimensional trials. These new approaches are strongly related to well-established methods for describing and analyzing error for one-dimensional tasks.     

Binaural and monaural localization of sound in two-dimensional space

Two experiments were conducted. In experiment 1, part 1, binaural and monaural localization of sounds originating in the left hemifield was investigated. 104 loudspeakers were arranged in a 13 x 8 matrix with 15 degrees separating adjacent loudspeakers in each column and in each row. In the horizontal plane (HP), the loudspeakers extended from 0 degrees to 180 degrees; in the vertical plane (VP), they extended from -45 degrees to 60 degrees with respect to the interaural axis. Findings of special interest were: (i) binaural listeners identified the VP coordinate of the sound source more accurately than did monaural listeners, and (ii) monaural listeners identified the VP coordinate of the sound source more accurately than its HP coordinate. In part 2, it was found that foreknowledge of the HP coordinate of the sound source aided monaural listeners in identifying its VP coordinate, but the converse did not hold. In experiment 2, part 1, localization performances were evaluated when the sound originated from consecutive 45 degrees segments of the HP, with the VP segments extending from -22.5 degrees to 22.5 degrees. Part 2 consisted of measuring, on the same subjects, head-related transfer functions by means of a miniature microphone placed at the entrance of their external ear canal. From these data, the 'covert' peaks (defined and illustrated in text) of the sound spectrum were extracted. This spectral cue was advanced to explain why monaural listeners in this study as well as in other studies performed better when locating VP-positioned sounds than when locating HP-positioned sounds. It is not claimed that there is inherent advantage for localizing sound in the VP; rather, monaural localization proficiency, whether in the VP or HP, depends on the availability of covert peaks which, in turn, rests on the spatial arrangement of the sound sources.     

IBM PC,PS/2, and compatibles

The ideas discussed in a group meeting of users of IBM PC, PS/2, and compatibles are summarized.     

An evaluation of statistical software for research and instruction

A variety of microcomputer statistics packages were evaluated. The packages were compared on a number of dimensions, including error handling, documentation, statistical capability, and accuracy. Results indicated that there are some very good packages available both for instruction and for analyzing research data. In general, the microcomputer packages were easier to learn and to use than were mainframe packages. Furthermore, output of mainframe packages was found to be less accurate than output of some of the microcomputer packages.