Detection and recognition: Concurrent processes in perception

In two experiments, event-related brain potentials (ERPs) were recorded while subjects performed a simultaneous detection and recognition task. Ten subjects listened to pure tones in noise and reported both whether a target tone had occurred (using a four-category confidence rating scale) and whether the target was one of two (Experiment 1) or four (Experiment 2) tones differing in frequency. The amplitudes of three ERP components were found to be differentially related to detection and recognition performance. The early N100 component varied with processing related only to detection, while the late P300 varied with both detection and recognition, and a later slow positive shift varied only with recognition and not with detection. While the latenciee of both N100 and P300 increased for less confident target detections, there were no differences in the latencies of these ERP components between correctly and incorrectly identiffed targets. Recognition performance was above the level expected by chance even when subjects reported that no target had been presented. The results indicate that brain potential components can be used to disclose temporal features of the processing of a stimulus by the nervous system and support the view that detection and recognition are partially independent, concurrent processes in perception.     

Perceived depth vs. structural relevance in the object-superiority effect

When subjects must identify a barely visible line in a briefly flashed display, their accuracy depends on the configuration of the context in which the target line appears. Weisstein and Harris (1974) found that accuracy is highest when the target is part of a pattern that resembles a unified, three-dimensional object, and lowest in a flat-looking pattern composed of disconnected lines; they labeled this phenomenon the object-superiority effect. In the three experiments reported here, identification accuracy was found to correlate highly and significantly (r =.78) with the judged depth of the patterns. Judged structural relevance of the target line to the pattern (McClelland & Miller, 1979) was uncorrelated with accuracy (r=?.28). Even when the target line appeared as an isolated fragment within the context pattern, a pattern perceived as three-dimensional yielded higher identification accuracy than one perceived as flat.     

Facial and vocal cues of deception and honesty

Facial expressions and vocal cues (filtered speech) of honest and deceptive messages were examined in posed and spontaneous situations. The question of interest was the degree to which nonverbal cues transmit information about deception. Results indicated that (a) for both the facial and vocal channels, posing (as compared to spontaneous behavior) produced a higher level of communication accuracy; (b) facial expressions of deceptive (as compared to honest) messages were rated as less pleasant, while vocal expressions of deception were rated as less honest, less assertive, and less dominant, particularly in the posed condition; (c) the sender's ability to convey honesty was negatively correlated with his/her ability to convey deception, suggesting the existence of a demeanor bias—individual senders tend to appear and sound consistently honest (or dishonest) regardless of whether they deliver an honest or a deceptive message; (d) in the posing condition, the sender's abilities to convey honesty/deception via facial and vocal cues were positively and significantly correlated, whereas in the spontaneous condition they were not; and (e) senders whose full (unfiltered) speech indicated more involvement with their responses were judged as more honest from both their vocal (filtered speech) and facial cues, in both the honest and deceptive conditions.     

Treatment of handwriting problems utilizing EMG biofeedback training.

The effects of EMG biofeedback training on cursive handwriting were investigated for 4 girls and 5 boys in Grade 4. A significant reduction in EMG between the first baseline session and the last training session was obtained. Four of 5 characteristics of handwriting improved significantly. The need for carefully designed research comparing EMG biofeedback training and relaxation training was indicated. A self-control factor in handwriting was hypothesized.     

TEACHING COIN EQUIVALENCE TO THE MENTALLY RETARDED1

A program was designed to teach coin equivalence to mentally retarded adolescents. Coin equivalence was defined as choosing several different combinations of coins to equal specified target values. A pretest-posttest matched-groups design was employed with an experimental group receiving the monetary training, and a no-training control group. A multiple baseline across coin-counting responses was also incorporated in the experimental group. Training was divided into six stages, each teaching one specific method of combining coins to equal 10 target values from 5¢ through 50¢. A three-component response chain was used, requiring (a) naming, (b) selecting and counting, and (c) depositing target monetary values into a coin machine. Experimental subjects improved significantly in coin equivalence performance and maintained their skill on follow up tests; control subjects did not.     

What do you do after you say hello? Observing,coding, and analyzing parent-infant interactions

Procedures for observing, coding, and analyzing parent-infant interactions are described. Sample data are presented to illustrate the outcome of these procedures and the manner in which developmental issues can be addressed using the hardware and software systems described.