Geometric analogue of holographic reduced representation

Holographic reduced representations (HRRs) are distributed representations of cognitive structures based on superpositions of convolution-bound n-tuples. Restricting HRRs to n-tuples consisting of ±1, one reinterprets the variable binding as a representation of the additive group of binary n-tuples with addition modulo 2. Since convolutions are not defined for vectors, the HRRs cannot be directly associated with geometric structures. Geometric analogues of HRRs are obtained if one considers a projective representation of the same group in the space of blades (geometric products of basis vectors) associated with an arbitrary n-dimensional Euclidean (or pseudo-Euclidean) space. Switching to matrix representations of Clifford algebras, one can always turn a geometric analogue of an HRR into a form of matrix distributed representation. In typical applications the resulting matrices are sparse, so that the matrix representation is less efficient than the representation directly employing the rules of geometric algebra. A yet more efficient procedure is based on ‘projected products’, a hierarchy of geometrically meaningful n-tuple multiplication rules obtained by combining geometric products with projections on relevant multivector subspaces. In terms of dimensionality the geometric analogues of HRRs are in between holographic and tensor-product representations.     

How emotion communication guides reciprocity: Establishing cooperation through disappointment and anger

Emotions fulfill many social functions, but data on their essential function of establishing cooperation are lacking. We investigated how communicating anger and disappointment guides reciprocal cooperative behavior. Although anger may force cooperation by announcing retaliation, we predicted that communicating disappointment was less likely to backfire. A laboratory study in which participants played against the reciprocal strategy of tit-for-tat showed that communicated disappointment established more cooperation than did anger. This effect also carried over to future cooperation decisions. Partners communicating disappointment evoked less anger, were evaluated more positively and as forgiving rather than retaliatory. Communication of disappointment thus appears conducive to establishing mutually beneficial relationships.     

Transfer of avoidance responding to a sensory preconditioned cue: Evidence for the role of S-S and R-S knowledge in avoidance learning

In avoidance learning studies, a warning signal (Sd) is directly paired with an aversive unconditioned stimulus (US) unless a particular response is performed. Research by Augustson and Dougher (1997) demonstrated that not only warning signals but also stimuli that are indirectly paired with the aversive event are capable of affecting the avoidance response. In the present study, we extended these results by incorporating a sensory preconditioning paradigm in an avoidance learning procedure. Sensory preconditioning training influenced the selection of avoidance responses in the presence of warning signals that were never paired directly with the aversive events. Moreover, results suggest that the selection of the avoidance responses was based on an integration of knowledge about the relation between the Sd and the US (S-S knowledge) and knowledge about the relation between the avoidance response and the US (R-S knowledge). As the expectancy-based theory of Lovibond (2006) is the only theory of avoidance that incorporates both knowledge structures, the results provide unique support for this theory.     

Visual and tactile action effects determine bimanual coordination performance

Effect-based models of motor control assign a crucial role to anticipated perceptual feedback in action planning. Two experiments were conducted to test the validity of this proposal for discrete bimanual key press responses. The results revealed that the normally observed performance advantage for the preparation of two responses with homologous rather than non-homologous fingers becomes inverted when homologous fingers produce non-identical visual effects, and non-homologous fingers produce identical visual effects. In the second experiment the finger homology effect was strongly reduced when homologous fingers produced non-identical tactile feedback. The results show that representations of to-be-produced visual and tactile action effects both contribute to action planning, though possibly to a varying degree. Implications of these results for effect-based models of motor control are considered.     

Imagination equally influences false memories of high and low plausibility events

To examine the effects of event plausibility on people's false beliefs and memories for imagined childhood events, subjects took part in a three‐stage procedure. First, subjects rated how confident they were that they had experienced certain childhood events. They also rated their memories of the events. Second, 1 week later, subjects imagined one high, one moderate and one low plausibility event. Third, 1 week later (and 2 weeks after their initial ratings), subjects rated their confidence and memory a second time. Imagining the events made subjects more confident that they were genuine experiences and gave subjects clearer and more complete memories. Plausibility did not affect subjects' confidence but it did affect their memories. Subjects developed clearer and more complete memories for high, followed by moderate, followed by low plausibility events regardless of whether those events were imagined. We use a nested model of plausibility, belief and memory to discuss our findings. Copyright © 2008 John Wiley & Sons, Ltd.     

Phonotactic regularities in the segmentation of spoken Italian

Five word-spotting experiments explored the role of consonantal and vocalic phonotactic cues in the segmentation of spoken Italian. The first set of experiments tested listeners' sensitivity to phonotactic constraints cueing syllable boundaries. Participants were slower in spotting words in nonsense strings when target onsets were misaligned (e.g., lago in ri.blago) than when they were aligned (e.g., lago in rin.lago) with phonotactically determined syllabic boundaries. This effect held also for sequences that occur only word-medially (e.g., /tl/ in ri.tlago), and competition effects could not account for the disadvantage in the misaligned condition. Similarly, target detections were slower when their offsets were misaligned (e.g., cittá in cittáu.ba) than when they were aligned (e.g., cittá in cittá.oba) with a phonotactic syllabic boundary. The second set of experiments tested listeners' sensitivity to phonotactic cues, which specifically signal lexical (and not just syllable) boundaries. Results corroborate the role of syllabic information in speech segmentation and suggest that Italian listeners make little use of additional phonotactic information that specifically cues word boundaries.     

How do People Evaluate Objects? A Brief Review

Evaluation can be defined either as the process of determining the liking of an object or as responding in an evaluative manner to objects. It can be studied by examining the evaluative responses that objects evoke. After justifying these definitions and this approach to the study of evaluation, I present a brief overview of what is known about the variables that influence evaluative responding. Finally, I describe the Associative-Propositional Evaluation model as an example of a theory about the mental processes that are assumed to underlie evaluative responding.     

Semisupervised category learning: The impact of feedback in learning the information-integration task

In a standard supervised classification paradigm, stimuli are presented sequentially, participants make a classification, and feedback follows immediately. In this article, we use a semisupervised classification paradigm, in which feedback is given after a prespecified percentage of trials only. In Experiment 1, feedback was given in 100%, 0%, 25%, and 50% of the trials. Previous research reported by Ashby, Queller, and Berretty (1999) indicated that in an information-integration task, perfect accuracy was obtained supervised (100%) but not unsupervised (0%). Our results show that in both the 100% and 50% conditions, participants were able to achieve maximum accuracy. However, in the 0% and the 25% conditions, participants failed to learn. To discover the influence of the no-feedback trials on the learning process, the 50% condition was replicated in Experiment 2, substituting unrelated filler trials for the no-feedback trials. The results indicated that accuracy rates were similar, suggesting no impact of the no-feedback trials on the learning process. The possibility of ever learning in a 25% setting was also researched in Experiment 2. Using twice as many trials, the results showed that all but 2 participants succeeded, suggesting that only the total number of feedback trials is important. The impact of the semisupervised learning results for ALCOVE, COVIS, and SPEED models is discussed.     

Behavioral consequences of agonistic experiences in the male S3 (Tryon Maze Dull) rat

Aggression occurring during an initial confrontation between two rats may result in significant behavioral changes in one or both animals. The present experiment was designed to study behavioral changes occurring in the course of an agonistic interaction and the consequences of winning or losing. In order to ensure winning, male CPB-S3 Tryon Maze Dull) rats were confronted with males of a more aggressive strain (Long Evans); and to ensure losing they were confronted with those of a less aggressive strain Wistar). Winners were tested against losers, this test being repeated after an interval of 17 days. Winners and losers were also tested with naive S3 opponents. Possible effects of winning and losing in nonagonistic behavioral tests were then examined. These measured open field activity, passive avoidance learning, and masculine sexual behavior. The results replicate and extend earlier findings using a different strain, indicating that significant and relatively permanent behavioral changes are induced in male winners and losers. Behavioral change is most prominent in the losers. Despite the behavioral differences between winners and losers in tests for agonistic behavior, no consistent differences were noted in any of the other behavioral tests.     

John Lind memorial symposium

John Lind, Professor of Pediatrics at the Karolinska Institute, emphasized that “the family is born in the maternity hospital.” He had a warm concern for all parents and infants and was extremely influential in both pediatric and child-rearing practices in Sweden and in the promotion of infant and caregiver-infant interaction research. Lind initiated and/or stimulated the scientific study of the infant's cry, parent-infant interactions, the role of the father in the perinatal environment, fetal and neonatal perception, and perinatal hospital practices. In many respects, his work predated contemporary emphases on perinatal coaching programs, social support (doula) during labor and delivery, parent education on childrearing, the use of ethnographic data for contemporary perinatal practices, interdisciplinary team approaches to study of infant care and development, changes in newborn nursery practices, and, above all, care and sensitivity to the initial synchronization of the parent-infant interaction system. This paper honors John Lind's contributions to our knowledge of infant development and parent-infant interaction, his influences on the field of pediatrics and the interdisciplinary study of infancy, and his commitment to enhancement of the quality of life for infants and their families. Although his life has ended, his ideas will continue to inspire and challenge the study of early human development for many years to come.