Chance-level hit rates in closed-set, forced-choice audiometry and a novel utility for the significance test-based detection of malingering

Effectiveness of the forced-choice coin test for detecting malingering during forensic psychiatric examinations

Background

In general clinical psychiatric practice, open questions are favored over closed ones because they are considered more therapeutically effective and less likely to make the patients pander to us. However, in forensic psychiatric examinations, suspects may attempt malingering.

Case Presentation

Using a simple examination based on a forced-choice technique, the author proved that the level of intelligence of a theft suspect pretending to have an intellectual developmental disorder was not so low. The author prepared two sets consisting of a few coins each and asked the suspect to choose which set had a higher total value. The suspect was questioned repeatedly over multiple trials. He always selected the wrong set over the course of more than 10 trials.

Conclusion

If the suspect really did not know the correct answer, the probability of getting the answer right or wrong in a binary choice question is 50% for both. The probability of answering the question wrong by chance 10 times in a row is (1/2),10 in other words, about 0.1%. It was evident that the suspect intentionally kept answering incorrectly. When suspects who pretend to have an intellectual developmental disorder answer only "I do not know" to all questions without actively playing out the symptoms, it is difficult to demonstrate that the symptoms are psychiatrically conflicting and prove that they are malingering. Even in such cases, this type of test based on a forced-choice technique can be used to prove that suspects are behaving falsely.

Perception and Production of Statement-Question Intonation in Autism Spectrum Disorder: A Developmental Investigation

Prosody or “melody in speech” in autism spectrum disorder (ASD) is often perceived as atypical. This study examined perception and production of statements and questions in 84 children, adolescents and adults with and without ASD, as well as participants’ pitch direction discrimination thresholds. The results suggested that the abilities to discriminate (in both speech and music conditions), identify, and imitate statement-question intonation were intact in individuals with ASD across age cohorts. Sensitivity to pitch direction predicted performance on intonation processing in both groups, who also exhibited similar developmental changes. These findings provide evidence for shared mechanisms in pitch processing between speech and music, as well as associations between low- and high-level pitch processing and between perception and production of pitch.

Listening to speech with a guinea pig-to-human brain-to-brain interface

Nicolelis wrote in his 2003 review on brain-machine interfaces (BMIs) that the design of a successful BMI relies on general physiological principles describing how neuronal signals are encoded. Our study explored whether neural information exchanged between brains of different species is possible, similar to the information exchange between computers. We show for the first time that single words processed by the guinea pig auditory system are intelligible to humans who receive the processed information via a cochlear implant. We recorded the neural response patterns to single-spoken words with multi-channel electrodes from the guinea inferior colliculus. The recordings served as a blueprint for trains of biphasic, charge-balanced electrical pulses, which a cochlear implant delivered to the cochlear implant user’s ear. Study participants completed a four-word forced-choice test and identified the correct word in 34.8% of trials. The participants' recognition, defined by the ability to choose the same word twice, whether right or wrong, was 53.6%. For all sessions, the participants received no training and no feedback. The results show that lexical information can be transmitted from an animal to a human auditory system. In the discussion, we will contemplate how learning from the animals might help developing novel coding strategies.

Impact of internal and external factors on prosocial choices in rhesus macaques

While traditional economic models assume that agents are self-interested, humans and most non-human primates are social species. Therefore, many of decisions they make require the integration of information about other social agents. This study asks to what extent information about social status and the social context in which decisions are taken impact on reward-guided decisions in rhesus macaques. We tested 12 monkeys of varying dominance status in several experimental versions of a two-choice task in which reward could be delivered to self only, only another monkey, both the self and another monkey, or neither. Results showed dominant animals were more prone to make prosocial choices than subordinates, but only when the decision was between a reward for self only and a reward for both self and other. If the choice was between a reward for self only and a reward for other only, no animal expressed altruistic behaviour. Finally, prosocial choices were true social decisions as they were strikingly reduced when the social partner was replaced by a non-social object. These results showed that as in humans, rhesus macaques' social decisions are adaptive and modulated by social status and the cost associated with being prosocial. This article is part of the theme issue 'Existence and prevalence of economic behaviours among non-human primates'.