A new approach to the formation of equivalence classes in pigeons

Four pigeons were given simultaneous discrimination training with visual patterns arbitrarily divided into two sets, with the stimuli in one set designated A1, B1, C1, and D1 and those in the other set designated A2, B2, C2, and D2. In sequentially introduced training phases, the pigeons were exposed to a series of reversals to establish AB and then CD equivalences. In subsequent testing sessions, a subset of stimuli from one set served as positive stimuli and those from the other set as negative stimuli on training trials, and transfer of the reinforced relation to other members of the sets was tested with nonreinforced probe trials. The pigeons were trained further on AC and BD equivalences and then were tested for the emergence of untrained AD and BC equivalences. Two of the 4 pigeons exhibited the emergence of one of these untrained equivalences, evidence for the emergence of transitive relations. This finding suggests that the pigeons established three-member functional equivalence classes by incorporating separately trained multiple equivalence relations. Repeated reversal training and probe testing enabled us to explore the formation and expansion of functional equivalence classes in pigeons.     

Preference for human direct gaze in infant chimpanzees (Pan troglodytes)

We studied gaze perception in three infant chimpanzees (Pan troglodytes), aged 10-32 weeks, using a two-choice preferential-looking paradigm. The infants were presented with two photographs of a human face: (a) with the eyes open or closed, and (b) with a direct or an averted gaze. We found that the chimpanzees preferred looking at the direct-gaze face. However, in the context of scrambled faces, the infants showed no difference in gaze discrimination between direct and averted gazes. These findings suggest that gaze perception by chimpanzees may be influenced by the surrounding facial context. The relationship between gaze perception, face processing, and the adaptive significance of gaze perception are discussed from an evolutionary perspective.     

Cognitions, metacognitions, and chronic pain

Purpose: Although the content of thoughts has received a considerable amount of attention in pain research, the importance of thought processes (metacognitions) has received less attention. Method: One hundred twenty-nine individuals with muscular dystrophy and chronic pain completed measures assessing metacognitions and frequency of both catastrophizing and pain control beliefs. Results: Greater use of reappraisal and distraction metacognitions were associated with more perceived control over pain, whereas greater use of worry and punishment metacognitions were associated with more catastrophizing. Conclusions/Implications: The current findings indicate that metacognitions are associated with both pain control beliefs and catastrophizing and therefore may play an important role in the development or maintenance of pain-related cognitive content thought to influence patient functioning. Research is needed to determine whether treatments that encourage changes in both metacognitions and cognitive content are more effective than treatments that focus on cognitive content alone. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Fourteen-month-old infants copy an action style accompanied by social-emotional cues

Human adults exaggerate their actions and facial expressions when interacting with infants. These infant-directed modifications highlight certain aspects of action sequences and attract infants’ attention. This study investigated whether social-emotional aspects of infant-directed modifications, such as smiling, eye contact, and onomatopoeic vocalization, influence infants’ copying of another's action, especially action style, during the process of achieving an outcome. In Study 1, 14-month-old infants (n = 22) saw an experimenter demonstrate goal-directed actions in an exaggerated manner. Either the style or the end state of the actions was accompanied by social-emotional cues from the experimenter. Infants copied the style of the action more often when social-emotional cues accompanied the style than when they accompanied the end state. In Study 2, a different group of 14-month-old infants (n = 22) watched the same exaggerated actions as in Study 1, except that either the style or the end state was accompanied by a physical sound instead of social-emotional cues. The infants copied the end state consistently more often than the style. Taken together, these two studies showed that accompanying social-emotional cues provided by a demonstrator, but not accompanying physical sound, increased infants’ copying of action style. These findings suggest that social-emotional cues facilitate efficient social learning through the adult–infant interaction.     

Discrimination of artificial polymorphous categories by rhesus monkeys (Macaca mulatta)

Monkeys (Macaca mulatta) were trained to discriminate between sets of artificial stimuli such as those used by Jitsumori (1993) for pigeons and humans. The stimuli were arrays of symbols differing along three two-valued (positive or negative) dimensions. The discrimination required was between polymorphous categories in which a positive stimulus was defined by possession of any 2 out of 3 positive features. Of the 5 monkeys, 3 learned the discrimination much faster than did pigeons, but transfer to novel stimuli was less impressive than had been shown in pigeons. The 3 monkeys showed high levels of transfer to the stimuli that contained either all 3 positive or all 3 negative features, but 2 of the 3 monkeys failed to show transfer to stimuli that had 1 of the 3 features replaced with a novel one. Analysis of the monkeys' performance raised doubts on the additive integration of features but supported learning of feature combinations as a basis for the discrimination of polymorphous categories by this species.     

Demystifying infant vocal imitation: The roles of mouth looking and speaker’s gaze

Vocal imitation plays a fundamental role in human language acquisition from infancy. Little is known, however, about how infants imitate other's sounds. We focused on three factors: (a) whether infants receive information from upright faces, (b) the infant's observation of the speaker's mouth and (c) the speaker directing their gaze towards the infant. We recorded the eye movements of 6‐month‐olds who participated in experiments watching videos of a speaker producing vowel sounds. We found that an infants’ tendency to vocally imitate such videos increased as a function of (a) seeing upright rather than inverted faces, (b) their increased looking towards the speaker's mouth and (c) whether the speaker directed their gaze towards, rather than away from infants. These latter findings are consistent with theories of motor resonance and natural pedagogy respectively. New light has been shed on the cues and underlying mechanisms linking infant speech perception and production.     

Discrimination of artificial categories structured by family resemblances: a comparative study in people (Homo sapiens) and pigeons (Columba livia)

Adult humans (Homo sapiens) and pigeons (Columba livia) were trained to discriminate artificial categories that the authors created by mimicking 2 properties of natural categories. One was a family resemblance relationship: The highly variable exemplars, including those that did not have features in common, were structured by a similarity network with the features correlating to one another in each category. The other was a polymorphous rule: No single feature was essential for distinguishing the categories, and all the features overlapped between the categories. Pigeons learned the categories with ease and then showed a prototype effect in accord with the degrees of family resemblance for novel stimuli. Some evidence was also observed for interactive effects of learning of individual exemplars and feature frequencies. Humans had difficulty in learning the categories. The participants who learned the categories generally responded to novel stimuli in an all-or-none fashion on the basis of their acquired classification decision rules. The processes that underlie the classification performances of the 2 species are discussed.     

The Association between Childhood Abuse and Labor Force Outcomes in Young Adults: Results from the Ontario Child Health Study

We examined the associations between childhood physical and sexual abuse and labor force outcomes in young adults and the possible mediating effects of educational attainment, current mental health, and physical health. Data from the Ontario Child Health Study (N = 1,893), a province-wide longitudinal study were analyzed. Controlling for childhood and demographic variables, severe childhood physical abuse was significantly associated with reduced income with small mediating effects. There was a sex difference in the association between child abuse and employment. Severe childhood physical abuse was significantly associated with lower likelihood of employment only among males; mediators partially reduced this association. Further research is needed to explore the mechanisms linking exposure to child abuse and economic vulnerability in young adults.     

Shrinkage in the perceived duration of speech and tone by acoustic replacement1

Abstract: To investigate mechanisms for perceiving the duration of an auditory event, an effect of perceptual grouping upon perceived duration was studied psychophysically. In the first experiment, the perceived duration of a spoken word was measured under three conditions of acoustic continuity (i.e., (a) intact, (b) noise‐replaced, and (c) gap‐replaced) as a function of the duration of the target stimulus. Under the noise‐replaced condition, a portion of the target stimulus was physically replaced with a noise burst. Under the gap‐replaced condition, the replacement was made with a gap. The gap‐replacement resulted in a prominent shrinkage of the perceived duration. In the case of noise‐replacement, the amount of shrinkage was moderate but highly significant, although the word employed was perceived to be phonetically intact. Independent of this effect of replacement, the amount of shrinkage was also affected by the physical duration of the target stimulus. The second experiment tested an effect of noise replacement on the perceived duration of a tone burst. In this case, the noise replacement also shrunk the perceived duration of the non‐speech stimulus. This noise‐induced shrinkage could be regarded as being general for the auditory duration. The phenomenon is discussed in relation to a revised model for perceived duration.