Development of a single-code/default coding strategy in pigeons

We tested the hypothesis that pigeons could use a cognitively efficient coding strategy by training them on a conditional discrimination (delayed symbolic matching) in which one alternative was correct following the presentation of one sample (one-to-one), whereas the other alternative was correct following the presentation of any one of four other samples (many-to-one). When retention intervals of different durations were inserted between the offset of the sample and the onset of the choice stimuli, divergent retention functions were found. With increasing retention interval, matching accuracy on trials involving any of the many-to-one samples was increasingly better than matching accuracy on trials involving the one-to-one sample. Furthermore, following this test, pigeons treated a novel sample as if it had been one of the many-to-one samples. The data suggest that rather than learning each of the five sample-comparison associations independently, the pigeons developed a cognitively efficient single-code/default coding strategy.     

“work ethic” in pigeons: Reward value is directly related to the effort or time required to obtain the reward

Stimuli associated with less effort or with shorter delays to reinforcement are generally preferred over those associated with greater effort or longer delays to reinforcement. However, the opposite appears to be true of stimuli thatfollow greater effort or longer delays. In training, a simple simultaneous discrimination followed a single peck to an initial stimulus (S+_FR1 S−_FR1) and a different simple simultaneous discrimination followed 20 pecks to the initial stimulus (S+_FR20 S−_FR20). On test trials, pigeons preferred S+_FR20 over S+_FR1 and S−_FR20 over S−_FR1. These data support the view that the state of the animal immediately prior to presentation of the discrimination affects the value of the reinforcement that follows it. This contrast effect is analogous to effects that when they occur in humans have been attributed to more complex cognitive and social factors.     

Liking persons versus liking groups: a dual-process hypothesis

Most research on liking of persons and groups has been conducted within separate paradigms, but the implicit assumption has been that the same processes govern judgments of liking or disliking regardless of the nature of the target. Departing from this assumption, we suggest a dual-process hypothesis according to which people base their liking of a target person primarily on the desirability of the person's characteristics, whereas they base their liking of a group primarily on the degree of similarity between the group and themselves. To test this hypothesis, participants were presented with either positively or negatively valenced sketches that either described an individual person or a group of people. Path analyses revealed that liking of a person was best predicted by desirability ratings, whereas liking of a group was best predicted by similarity ratings. Implications of these findings for stereotype maintenance are discussed. © 1998 John Wiley & Sons, Ltd.     

“Hey,let me hold your guns for a while”: A qualitative study of messaging for firearm suicide prevention

A recommended component of suicide prevention is encouraging at‐risk individuals to voluntarily and temporarily reduce access to firearms and other lethal methods. Yet delivering counseling on the topic can be difficult, given the political sensitivity of firearm discussions. To support such counseling, we sought to identify recommended framing and content of messages about reducing firearm access for suicide prevention. Through qualitative interviews with firearm owners and enthusiasts, we identified key points for use in framing (identity as a gun owner, trust, voluntary and temporary storage, and context and motivation) and specific content (preference for “firearm” over “gun,” and legal issues such as background checks for transfers). These findings build on prior work and should enhance efforts to develop and deliver effective, acceptable counseling and—ultimately—prevent firearm suicide.     

Reply to Professor Baker

International Journal for Philosophy of Religion -     

Interplay between acoustic/phonetic and semantic processes during spoken sentence comprehension: an ERP study

When listening to speech in everyday-life situations, our cognitive system must often cope with signal instabilities such as sudden breaks, mispronunciations, interfering noises or reverberations potentially causing disruptions at the acoustic/phonetic interface and preventing efficient lexical access and semantic integration. The physiological mechanisms allowing listeners to react instantaneously to such fast and unexpected perturbations in order to maintain intelligibility of the delivered message are still partly unknown. The present electroencephalography (EEG) study aimed at investigating the cortical responses to real-time detection of a sudden acoustic/phonetic change occurring in connected speech and how these mechanisms interfere with semantic integration. Participants listened to sentences in which final words could contain signal reversals along the temporal dimension (time-reversed speech) of varying durations and could have either a low- or high-cloze probability within sentence context. Results revealed that early detection of the acoustic/phonetic change elicited a fronto-central negativity shortly after the onset of the manipulation that matched the spatio-temporal features of the Mismatch Negativity (MMN) recorded in the same participants during an oddball paradigm. Time reversal also affected late event-related potentials (ERPs) reflecting semantic expectancies (N400) differently when words were predictable or not from the sentence context. These findings are discussed in the context of brain signatures to transient acoustic/phonetic variations in speech. They contribute to a better understanding of natural speech comprehension as they show that acoustic/phonetic information and semantic knowledge strongly interact under adverse conditions.     

Hand preference and its flexibility according to the position of the object: a study in cercopithecines examining spontaneous behaviour and an experimental task (the Bishop QHP task)

The extant literature on manual laterality in non-human primates is inconclusive, plagued by inconsistent or contradictory findings and by disturbing methodological issues (e.g. uncontrolled influential factors, comparability issues). The present study examined hand preference and its flexibility in 15 red-capped mangabeys (C. t. torquatus) and 13 Campbell's monkeys (C. c. campbelli), two species that differ in their degree of arboreality. We investigated the influence of the spatial position of the object on hand preference for reaching. We considered spontaneous behaviour (reaching for food during daily feeding) and an experimental task: the QHP task. The QHP is a task that is used in humans. This is a simple reaching task that involves high spatial constraints on hand use. In our study, the subject had to reach for items that were placed on a semi-circle in front of it on five positions, including in the centre position, in the ipsilateral space and in the contralateral space. We assessed hand preference for reaching in front (baseline condition), and we examined how this preference changed when reaching in lateral positions. For reaching in front, about half of the subjects were lateralized and no group-level bias occurred, for both spontaneous and experimental conditions. When considering reaching in the lateral positions, we observed that the position of the object influenced hand use: individuals used the hand that was closest to the object. The results are discussed in relation to previous findings in humans and in non-human primates and regarding theories on handedness and flexibility of hand preference.