Comparison of yes-no and latency measures of auditory intensity discrimination.

Rats discriminated auditory intensity differences of sinusoids at 3.0 kilohertz in a go/no-go signal detection procedure. Responses to the signal (hits) were reinforced with electrical brain stimulation, and misses produced a brief timeout. On intermixed noise trials, withholding of responses (correct rejections) was reinforced, and false alarms produced the time-out. In two test conditions, the signal was either the louder (100 decibels) or softer (90, 93, 96, or 99 decibels) of the pair of intensities presented within a set of trials. Each animal was first trained with signal value louder or softer, and reversed for the second condition so that the former noise value served as signal. Hits showed shorter latencies than false alarms, regardless of the relative intensity of signal and noise, and the magnitude of differentiation was proportional to signal-noise separation. Both hits and false alarms showed longer latencies as the discrimination became more difficult. Isosensitivity contours derived from the latencies showed close similarity across conditions; in comparison, the yes-no measure of detectability, d', showed greater variability. The similarity of latency differentiation across louder and softer signal conditions supports a detection model in which the observer's judgment is controlled by the distance of sensory effect from criterion on each trial, as opposed to the loudness of the tones per se.     

Prenatal discrimination of a male and a female voice uttering the same sentence

Using a habituation/dishabituation procedure, near-term foetuses (36-39 weeks gestational age) were tested in a low variability HR state, to examine whether they could discriminate between a male and a female voice repeatedly uttering the same short sentence. Prosody and loudness of the two voices were controlled. Once the foetal heart rate (HR) habituated to the first voice, the effect of a second voice was investigated in two experimental conditions: male/female voice and female/male voice. HR variations after the onset of the second voice were compared to those occurring in two control conditions in which the same voice was presented twice (male/female voice and female/female voice). Highly conservative statistical criteria taking each subject's pre-stimulus HR variability into account showed that most foetuses exposed to the voice change displayed decelerative cardiac changes, with no significant difference between the two conditions. These HR decelerations were found in the first seconds following the onset of the new voice, and reached their peak amplitude within 10 s in most subjects. These responses lasted more than 10 s for two-thirds of the experimental subjects. Mostly transient HR accelerations and only a few decelerative changes were recorded in the control subjects. Furthermore, mean amplitudes of these changes were significantly lower than the HR decelerations induced by the new voice in the experimental conditions, suggesting that the latter were not spontaneous HR modifications but rather cardiac responses to the voice change. It is argued that near-term foetuses may perceive a difference between voice characteristics of two speakers when they are highly contrasted for fundamental frequency and timbre.     

Behavior-Based Assessment of the Auditory Abilities of Brushtail Possums

Brushtail possums (Trichosurus vulpecula) were trained to press a right lever when a tone was presented (a tone‐on trial) and a left lever when a tone was not presented (a tone‐off trial) to gain access to food. During training the tone was set at 80 dB(A), with a frequency of 0.88 kH for 3 possums and of 4 kH for the other 2. Once accuracy was over 90% correct across five consecutive sessions, a test session was conducted where the intensity of the tone was reduced by 8 dB(A) over blocks of 20 trials until accuracy over a block fell below 60%. After each test session, training sessions were reintroduced and continued until accuracy was again over 90%, when another test session was conducted. This process continued until there were at least five test sessions at that tone frequency. The same procedure was then used with frequencies of 0.20, 0.88, 2, 4, 10, 12.5, 15, 20, 30, and 35 kHz. Percentage correct and d' decreased approximately linearly for all possums as tone intensity reduced. Both sets of lines were shallowest at the higher frequencies and steepest at the lower frequencies. Hit and false alarm rates mirrored each other at high frequencies but were asymmetric at lower frequencies. Equal d' contours showed that sensitivity increased from 2 to 15 kHz and continued to be high over 20 to 35 kHz. The possums remained sensitive to the 20 to 35 kHz tones even at low intensities. The present study is the first to report the abilities of possum to detect tones over this range of frequencies and its results support the findings of a microelectrode mapping survey of possums' auditory cortex.     

Methods and aims of investigative interviewing of adult witnesses: An analysis of professional practices

Eyewitnesses provide crucial evidence for the investigation of criminal cases. We analysed professional police interviewers’ behaviour by conducting a literature review. Our results indicate that the interviewing techniques used by untrained and trained investigators are predominantly inappropriate and harmful to memory recall. The way investigators curtail and select witnesses’ responses suggests that they look for specific information. As a subsequent step, we analysed investigative interviewing in terms of professional objectives, identifying the types of information that the police inquire about during the interview. Based on our results, we conclude future research should perform a fine-grained analysis of professional interviewing procedures with the aim of producing effective interviewing techniques that meet investigators’ real-world objectives.     

Multisensory Information in the Control of Complex Motor Actions

ABSTRACT— For many of the complex motor actions we perform, perceptual information is available from several different senses including vision, touch, hearing, and the vestibular system. Here I discuss the use of multisensory information for the control of motor action in three particular domains: aviation, sports, and driving. It is shown that performers in these domains use information from multiple senses—frequently with beneficial effects on performance but sometimes with dangerous consequences. Applied psychologists have taken advantage of our natural tendency to integrate sensory information by designing multimodal displays that compensate for situations in which information from one or more of our senses is unreliable or is unattended due to distraction.