Primates do not spontaneously use shape properties for object individuation: a competence or a performance problem?

Several recent studies have documented that non-human primates can individuate objects according to property and/or kind information in much the same way as human infants do from around one year of age when they begin to acquire language. Some studies suggest, however, that only some properties are used for the individuation of food items: color, but not shape. The present study investigated whether these findings reveal a true competence problem with shape properties in the food domain or whether they merely reveal a performance problem (e.g., lack of attention to shapes). We tested 25 great apes (chimpanzees, bonobos and gorillas) in two food individuation tasks. We manipulated subjects’ experience with differences in color and shape properties of food items. Results indicated (i) that all subjects, regardless of their prior experience, solved the color-based object individuation task and (ii) that only the group with previous experience with different shape properties succeeded in the shape-based individuation task. Great apes can thus be primed to take shape into account for individuating food objects, and this results clearly speaks in favor of a performance (rather than a competence) problem in using shape for object individuation of food items.     

Why Do Young Children Look so Smart and Older Children Look so Dumb on True Belief Control Tasks? An Investigation of Pragmatic Performance Factors

ABSTRACT

When do children acquire a meta-representational Theory of Mind? False Belief (FB) tasks have become the litmus test to answer this question. In such tasks, subjects must ascribe a non-veridical belief to another agent and predict/explain her actions accordingly. Empirically, children pass explicit verbal versions of FB tasks from around age 4. The standard interpretation of this finding is that children at this age have acquired a solid capacity for meta-representation. New research with true belief (TB) control tasks, however, presents a puzzling phenomenon: While 3-year-olds pass these tasks but fail FB tasks, children from age 4 begin to show the reverse performance (passing FB but failing TB). Competence deficit accounts claim that these findings jeopardize the standard interpretation; they show that children may use simple heuristics rather than true meta-representation and that the original FB findings may thus have been false positives. Pragmatic performance limitation accounts, in contrast, claim that these findings do not document any conceptual limitations, but merely reflect children’s confusion in light of the task pragmatics. In the present study, the two accounts were tested against each other in seven experiments with 4- to 7-year-old children. Pragmatic tasks factors of TB tests were systematically modified. Results show that children’s difficulty with TB tasks indeed disappeared after some such modifications. This clearly speaks against competence limitation accounts and corroborates the standard interpretation of FB and related Theory of Mind tasks.     

Object Individuation in the Absence of Kind-specific Surface Features: Evidence for a Primordial Essentialist Stance?

ABSTRACT

It has been suggested that due to functional similarity, sortal object individuation might be a primordial form of psychological essentialism. For example, the relative independence of identity judgment from perceived surface features is a characteristic of essentialist reasoning. Also, infants engaging in sortal object individuation pay more attention to kind than surface feature information when judging the identity of objects (e.g.). Indeed, previous research found that 14-month-old infants can judge trans-temporal identity even in complete absence of kind-specific surface features. Here, we used another more demanding non-linguistic paradigm to test the limits of these abilities in 14-, 18-, 23- and 36-month-old infants, comparing their performance to recent great ape data. Particularly, we presented infants with two food kinds, whose surface features were then fully transformed to make them look identical. If reasoning according to essentialist principles, participants should select the preferred item despite superficial manipulations. However, only 36-month-olds reliably tracked the preferred item after superficial manipulations. This suggests that, although basic psychological essentialism may emerge early in infancy, more complex forms require domain-general cognitive prerequisites, which only develop in more protracted form.     

The auditory redundant signals effect: An influence of number of stimuli or number of percepts?

In two experiments, we examined simple reaction times (RTs) for detection of the onsets and offsets of auditory stimuli. Both experiments assessed the redundant signals effect (RSE), which is traditionally defined as the reduction in RT associated with the presentation of two redundant stimuli, rather than a single stimulus. In Experiment 1, with two identical tones presented via headphones to the left ear, right ear, or both, no RSE was found in responding to tone onsets, but a large RSE was found in responding to their offsets. In Experiment 2, with a pure tone and white noise as the two stimulus alternatives, RSEs were found for responding to both onsets and offsets. The results support the notion that the occurrence of an RSE depends on the number of percepts, rather than the number of stimuli, and on the requirement to respond to stimulus onsets versus offsets. The parallel grains model (Miller & Ulrich, 2003) provides one possible account of this pattern of results.     

No Future

The difficulties with formalizing the intensional notions necessity, knowability and omniscience, and rational belief are well-known. If these notions are formalized as predicates applying to (codes of) sentences, then from apparently weak and uncontroversial logical principles governing these notions, outright contradictions can be derived. Tense logic is one of the best understood and most extensively developed branches of intensional logic. In tense logic, the temporal notions future and past are formalized as sentential operators rather than as predicates. The question therefore arises whether the notions that are investigated in tense logic can be consistently formalized as predicates. In this paper it is shown that the answer to this question is negative. The logical treatment of the notions of future and past as predicates gives rise to paradoxes due the specific interplay between both notions. For this reason, the tense paradoxes that will be presented are not identical to the paradoxes referred to above.     

Taking fiction seriously: young children understand the normative structure of joint pretence games

Joint pretence games are implicit rule-governed activities with a normative structure: Given shared fictional stipulations, some acts are appropriate moves, others are inappropriate (i.e., mistakes). The awareness of 2- and 3-year-old children of this normative structure was explored, as indicated by their ability to not only act according to the rules themselves but to spontaneously protest against 3rd party rule violations. After the child and a 2nd person had set up a pretence scenario, a 3rd character (a puppet controlled by another experimenter) joined the game and performed acts either appropriate or inappropriate to the scenario set-up. Children in both age groups protested specifically against inappropriate acts, indicating they were able to not only follow pretence stipulations and act in accordance with them but to understand their deontic implications. This effect was more pronounced in the 3-year-olds than in the 2-year-olds. The results are discussed in the broader context of the development of social understanding and cultural learning.