Repetition blindness: an emergent property of inter-item competition

Repeating an item in a brief or rapid display usually produces faster or more accurate identification of the item (repetition priming), but sometimes produces the opposite effect (repetition blindness). We present a theory of short-term repetition effects, the competition hypothesis, which explains these paradoxical outcomes. The central tenet of the theory is that repetition produces a representation with a higher signal-to-noise ratio but also produces a disadvantage in the representation’s ability to compete with other items for access to awareness. A computational implementation of the competition hypothesis was developed to simulate standard findings in the RB literature and to generate novel predictions which were then tested in three experiments. Results from these experiments suggest that repetition effects emerge from competitive interactions between items and that these influences extend to adjacent, nonrepeated items in the display. The results also present challenges to existing theories of short-term repetition effects.     

What exactly is a yait anyway: The role of semantics in orthographic learning

This study investigated whether semantic information presented along with novel printed nonwords facilitates orthographic learning and examined predictors of individual differences in this important literacy skill. A sample of 35 fourth graders was tested on a variety of language and literacy tests, and participants were then exposed to 10 target nonwords, 5 of which were presented with semantic information. Children were tested 1 and 4 days later on their ability to correctly recognize and spell the target nonwords. Results revealed a significant main effect on the recognition task, where items presented with semantic information were identified correctly more often than were words presented in isolation. No significant effect of training condition was found for the spelling posttests. Furthermore, multiple regression analyses revealed that both phonological and semantic factors were significant predictors of orthographic learning. The findings support the view that orthographic learning, as measured through visual recognition, involves the integration of phonological, orthographic, and semantic representations.     

Two are better than one: comparison influences infants' visual recognition memory

Despite a large literature on infants’ memory for visually presented stimuli, the processes underlying visual memory are not well understood. Two studies with 4-month-olds (N = 60) examined the effects of providing opportunities for comparison of items on infants’ memory for those items. Experiment 1 revealed that 4-month-olds failed to show evidence of memory for an item presented during familiarization in a standard task (i.e., when only one item was presented during familiarization). In Experiment 2, infants showed robust memory for one of two different items presented during familiarization. Thus, infants’ memory for the distinctive features of individual items was enhanced when they could compare items.     

Preference for impossible figures in 4-month-olds

Can infants use interposition and line junction cues to infer three-dimensional (3D) structure? Previous work has shown that in a task that required 4-month-olds to discriminate between static two-dimensional (2D) pictures of possible and impossible cubes, infants exhibited a spontaneous preference for displays of the impossible cube but left open the question of whether they did so on the basis of purely local “critical regions” or whether they were able to employ more global clues. Here infants were presented with possible and impossible cubes in which the strictly local cues that could have derived from exterior binding contours were deleted. Results showed that infants were still able to discriminate possible cubes from impossible cubes, suggesting that longer looking infants are sensitive to global properties and that the capacity to integrate pictorial information to perceive aspects of global 3D shape may develop earlier than demonstrated previously using reaching tasks.     

The hidden persuaders break into the tired brain

There is a long-lasting debate on whether subliminal advertising actually works. In this context there are some studies suggesting that subjects’ motivation is a crucial point. Karremans et al. [Karremans, J. C., Stroebe, W., & Claus, J. (2006). Beyond Vicary’s fantasies: The impact of subliminal priming and brand choice. Journal of Experimental Social Psychology, 42, 792-798] showed that subjects were influenced in their intention to drink a specific brand of soft drink by a subliminally presented brand prime, but only if they were thirsty. In the present study, we adapted their paradigm to the concept of ‘concentration’ and embedded the subliminal presentation of a brand logo into a computer game. Actual subsequent consumption of dextrose pills (of the presented or a not presented brand) was measured dependent on the level of participants’ tiredness and the subliminally presented logo. We found the same pattern as Karremans et al. (2006): only tired participants consumed more of the subliminally presented than the not presented brand. Therefore, the findings confirm that subjects are influenced by subliminally presented stimuli if these stimuli are need-related and if subjects are in the matching motivational state.     

Aberrant pattern of scanning in prosopagnosia reflects impaired face processing

Visual scanpath recording was used to investigate the information processing strategies used by a prosopagnosic patient, SC, when viewing faces. Compared to controls, SC showed an aberrant pattern of scanning, directing attention away from the internal configuration of facial features (eyes, nose) towards peripheral regions (hair, forehead) of the face. The results suggest that SC's face recognition deficit can be linked to an inability to assemble an accurate and unified face percept due to an abnormal allocation of attention away from the internal face region. Extraction of stimulus attributes necessary for face identity recognition is compromised by an aberrant face scanning pattern.     

Neurophysiological evidence for categorical perception of color

The aim of this investigation was to examine the time course and the relative contributions of perceptual and post-perceptual processes to categorical perception (CP) of color. A visual oddball task was used with standard and deviant stimuli from same (within-category) or different (between-category) categories, with chromatic separations for within- and between-category stimuli equated in Munsell Hue. CP was found on a behavioral version of the task, with faster RTs and greater accuracy for between- compared to within-category stimuli. On a neurophysiological version of the task, event-related potentials (ERPs) showed earlier latencies for P1 and N1 components at posterior locations to between- relative to within-category deviants, providing novel evidence for early perceptual processes on color CP. Enhanced P2 and P3 waves were also found for between- compared to within-category stimuli, indicating a role for later post-perceptual processes.     

Semantic asymmetries are modulated by phonological asymmetries: Evidence from the disambiguation of homophonic versus heterophonic homographs

The present study investigated cerebral asymmetries in accessing multiple meanings of two types of homographs: homophonic homographs (e.g., bank) and heterophonic homographs (e.g., tear). Participants read homographs preceded by either a biasing or a non-biasing sentential context and performed a lexical decision on lateralized targets presented 150 ms after onset of the sentence-final ambiguous prime. Targets were either related to the dominant or the subordinate meaning of the preceding homograph or were unrelated to it. In the case of homophonic homographs – our results converge with previous findings: both activation and selection processes are faster in the LH than in the RH. Importantly, however, in the case of heterophonic homographs – opposite asymmetries were found. These results suggest that semantic asymmetries are modulated by phonology. They are discussed in the context of a model of functional architecture of reading in the two hemispheres in which orthography, phonology and semantics are fully interconnected in the LH, whereas in the RH, orthography and phonology are not directly connected, such that phonological processes are mediated by semantics.     

The egocentric reference for visual exploration and orientation

Clinical signs of damage to the egocentric reference system range from the inability to detect stimuli in the real environment to a defect in recovering items from an internal representation. Despite clinical dissociations, current interpretations consider all symptoms as due to a single perturbation, differentially expressed according to the medium explored (perceptual or representational). We propose an alternative account based on the functional distinction between two separate egocentric mechanisms: one allowing construction of the immediate point of view, the other extracting a required perspective within a mental representation. Support to this claim comes from recent results in the domain of navigation, showing that separate cognitive mechanisms maintain the egocentric reference when actively exploring the visual space as opposed to moving according to an internal map. These mechanisms likely follow separate developmental pathways, seemingly depend on distinct neural pathways and are used independently by healthy adults, reflecting task demands and individual cognitive style. Implications for spatial cognition and social skills are discussed.     

Behavioral and neuronal attributes of short- and long-term habituation in the crab Chasmagnathus

Investigations using invertebrate species have led to a considerable progress in our understanding of the mechanisms underlying learning and memory. In this review we describe the main behavioral and neuronal findings obtained by studying the habituation of the escape response to a visual danger stimulus in the crab Chasmagnathus granulatus. Massed training with brief intertrial intervals lead to a rapid reduction of the escape response that recovers after a short term. Conversely, few trials of spaced training renders a slower escape reduction that endures for many days. As predicted by Wagner’s associative theory of habituation, long-term habituation in the crab proved to be determined by an association between the contextual environment of the training and the unconditioned stimulus. By performing intracellular recordings in the brain of the intact animal at the same time it was learning, we identified a group of neurons that remarkably reflects the short- and long-term behavioral changes. Thus, the visual memory abilities of crabs, their relatively simple and accessible nervous system, and the recording stability that can be achieved with their neurons provide an opportunity for uncovering neurophysiological and molecular events that occur in identifiable neurons during learning.