On interference between target and noise in visual stimuli

Visual stimuli in which a target is presented on a background of noise have been used widely in visionresearch. Adding a background of noise tends to reduce performance. Such reductions have typically beenattributed to factors in the visual system. The present analyses demonstrates how there may be interferencebetween target and noise. This interference takes place in the stimuli rather than in the visual system. Ittakes place even if the stimuli are not being seen. The interference causes the amplitudes in the combinedtarget and noise stimulus to be smaller than the amplitudes in the target plus the amplitudes in the noisewhen these are determined separately. Therefore, the full amplitudes of the target and those of the noisecannot all be contained in the amplitudes of the combined stimulus. As a consequence one cannot counton a target stimulus to have the same stimulus power when presented on a background of noise as whenpresented on a uniform background.

Muscimol-induced inactivation of the anterior cingulate cortex does not impair trace fear conditioning in the rat

Previous studies suggest that trace conditioning depends on the anterior cingulate cortex (ACC). To examine the role of ACC in trace fear conditioning further, 48 rats were surgically prepared for infusion with saline or 62.5 or 125 µg/side muscimol to inactivate ACC reversibly prior to conditioning. A noise stimulus was followed by a 1 mA footshock, with or without a 10-second trace interval between these events in a conditioned suppression procedure. The trace-conditioned groups (10 seconds) showed less test suppression than the control-conditioned groups (0 seconds). Counter to prediction, there was no effect of muscimol infusion on suppression to the noise stimulus in the 10-second trace groups.

PSV-7 Effects of music stimulus on behavior response, cortisol level and immunity horizontal of growing pigs

Enrichment environment is widely used to improve the welfare of domestic animals and satisfy their natural behavior. Music as an enriched environment can reduce abnormal behavior in humans, non-human primates and rodents. The aim of this study was to investigate the effects of repeated music stimuli on the behavior, physiology and immunity of growing pigs. A total of 72 5-week-old hybrid piglets (Large White × Duroc × Minpig) were randomly divided into three treatments groups of the music group (Mozart K.448, 65–70 dB), the noise group (mechanical noise, 85–90 dB) and the control group (silence, less than 40dB). During 60 days of auditory exposure, the behavioral responses, cortisol level and immune horizontal of the piglets were measured. The results showed that the active behavior of the growing pigs increased and lying behavior decreased in the music group compared to the control group (P < 0.05). The music stimulus increased tail wagging, tail in curl and playing behaviors (P < 0.05). The noise stimulus increased aggressive behavior (P < 0.05) but had no effect on the exploring and manipulative behaviors (P > 0.05). The frequency of the event behaviors decreased with the time of auditory stimuli (P < 0.05). Short-term music stimulus had a lower cortisol level than the noise and control groups (P < 0.05). Long-term music stimulus increased the level of IgG, IL-2 and IFN-γ (P < 0.05) and decreased the IL-4 level (P < 0.05). Noise stimulus reduced the level of IgG (P < 0.05) but had no effect on the level of IL-2, IL-4 and IFN-γ (P > 0.05). In conclusion, music stimulus triggers the pigs to show more positive behaviors, and the short-term music stimulus can reduce the stress response, while the long-term music stimulus can enhance the immune responses in the growing pigs.

Detection Thresholds for Combined Infrasound and Audio-Frequency Stimuli

This study investigated whether the presence of audio sound (20 Hz < frequency f < 20 kHz) influences the detection threshold for infrasound (f < 20 Hz), and, vice versa, whether the presence of infrasound influences the detection threshold for audio sound. Monaural detection thresholds of thirteen otologically normal listeners were repeatedly determined for infrasound stimuli (sinusoids at 5 Hz and at 12 Hz) and for audio sound stimuli (sinusoids and bandlimited pink noise), separately and in presence of the respective other sound type. The measurements were performed with an adaptive 1-up-2-down 3-alternative forced-choice (3-AFC) procedure. Threshold levels for infrasound stimuli were not affected by audio sound at +5 dB sensation level (SL), but they were significantly increased by the presence of some of the audio sound stimuli presented at +50 dB SL. For example, thresholds for the detection of infrasound increased on average by around 5 dB when simultaneously presented with a pink-noise stimulus (frequency range: 250 Hz– 4000 Hz). On the other hand, the presence of infrasound with levels up to +10 dB SL did not cause any significant change in the detection thresholds for audio sound. This could be an indication that infrasound might even be more annoying in a quiet environment.

Comparison between the auditory lateralization ability of normal hearing elderly and youth with filtered noise

Background and Aim: Aging affects the audi­tory lateralization function that is achieved thr­ough processing binaural cues. One of the most important benefits of this process, along with getting informed of sound location, is increasing signal to noise ratio and improvement of speech comprehension in crowded environments, which is one of the most common hearing complaints in the elderly. This study aimed to compare the performance of the lateralization function under the headphone conditions between the elderly and the youth, with a filtered noise stimulus. Methods: This study was performed between 22 elderly aged 60−80 and 22 young people aged 20−30. The auditory threshold was less than 25 dB HL in 250 to 4000 Hz frequencies in both groups. By applying a time delay of −880 to +880 microsecond and the intensity differe­nce of −10 to +10 dB between the two ears, and with high-pass and low-pass noise stimulus, the lateralization function was examined. For descr­iption of the lateralization function, scatter diag­ram and in order to compare the results, paired t-test and independent t-test were used. Results: Findings showed that the elderly's err­ors were increased in all tests compared to those of the youth group. There was a significant difference (p < 0.05) between the two groups in lateralization by time clues with low-pass and high-pass noise. Conclusion: Results confirm the impairment of the lateralization and processing of binaural cues in the elderly differently.

Auditory Stimulus Processing and Task Learning Are Adequate in Dyslexia, but Benefits From Regularities Are Reduced

Purpose The reading deficit for people with dyslexia is typically associated with linguistic, memory, and perceptual-discrimination difficulties, whose relation to reading impairment is disputed. We proposed that automatic detection and usage of serial sound regularities for individuals with dyslexia is impaired (anchoring deficit hypothesis), leading to the formation of less reliable sound predictions. Agus, Carrión-Castillo, Pressnitzer, and Ramus, (2014) reported seemingly contradictory evidence by showing similar performance by participants with and without dyslexia in a demanding auditory task that contained task-relevant regularities. To carefully assess the sensitivity of participants with dyslexia to regularities of this task, we replicated their study. Method Thirty participants with and 24 without dyslexia performed the replicated task. On each trial, a 1-s noise stimulus was presented. Participants had to decide whether the stimulus contained repetitions (was constructed from a 0.5-s noise segment repeated twice) or not. It is implicit in this structure that some of the stimuli with repetitions were themselves repeated across trials. We measured the ability to detect within-noise repetitions and the sensitivity to cross-trial repetitions of the same noise stimuli. Results We replicated the finding of similar mean performance. However, individuals with dyslexia were less sensitive to the cross-trial repetition of noise stimuli and tended to be more sensitive to repetitions in novel noise stimuli. Conclusion These findings indicate that online auditory processing for individuals with dyslexia is adequate but their implicit retention and usage of sound regularities is indeed impaired.