Intersensory redundancy facilitates prenatal perceptual learning in bobwhite quail (Colinus virginianus) embryos.

Information presented redundantly and in temporal synchrony across sensory modalities (intersensory redundancy) selectively recruits attention and facilitates perceptual learning in human infants. This comparative study examined whether intersensory redundancy also facilitates perceptual learning prenatally. The authors assessed quail (Colinus virginianus) embryos' ability to learn a maternal call when it was (a) unimodal, (b) concurrent but asynchronous with patterned light, or (c) redundant and synchronous with patterned light. Chicks' preference for the familiar over a novel maternal call was assessed 24 hr following hatching. Chicks receiving redundant, synchronous stimulation as embryos learned the call 4 times faster than those who received unimodal exposure. Chicks who received asynchronous bimodal stimulation showed no evidence of learning. These results provide the first evidence that embryos are sensitive to redundant, bimodal information and that it can facilitate learning during the prenatal period.     

Intersensory redundancy accelerates preverbal numerical competence

Intersensory redundancy can facilitate animal and human behavior in areas as diverse as rhythm discrimination, signal detection, orienting responses, maternal call learning, and associative learning. In the realm of numerical development, infants show similar sensitivity to numerical differences in both the visual and auditory modalities. Using a habituation-dishabituation paradigm, we ask here, whether providing redundant, multisensory numerical information allows six-month-old infants to make more precise numerical discriminations. Results indicate that perceptually redundant information improved preverbal numerical precision to a level of discrimination previously thought attainable only after additional months of development. Multimodal stimuli may thus boost abstract cognitive abilities such as numerical competence.     

Intersensory redundancy guides attentional selectivity and perceptual learning in infancy

This study assessed an intersensory redundancy hypothesis, which holds that in early infancy information presented redundantly and in temporal synchrony across two sense modalities selectively recruits attention and facilitates perceptual differentiation more effectively than does the same information presented unimodally. Five-month-old infants' sensitivity to the amodal property of rhythm was examined in 3 experiments. Results revealed that habituation to a bimodal (auditory and visual) rhythm resulted in discrimination of a novel rhythm, whereas habituation to the same rhythm presented unimodally (auditory or visual) resulted in no evidence of discrimination. Also, temporal synchrony between the bimodal auditory and visual information was necessary for rhythm discrimination. These findings support an intersensory redundancy hypothesis and provide further evidence for the importance of redundancy for guiding and constraining early perceptual learning.     

Prenatal experience and postnatal perceptual preferences: evidence for attentional-bias in bobwhite quail embryos (Colinus virginianus)

Previous studies have indicated that concurrent multimodal sensory stimulation can interfere with prenatal perceptual learning. This study further examined this issue by exposing 3 groups of bobwhite quail embryos (Colinus virginianus) to (a) no supplemental stimulation, (b) a bobwhite maternal call, or (c) a maternal call paired with a pulsating light in the period prior to hatching. Experiments differed in terms of the types of stimuli presented during postnatal preference tests. Embryos receiving no supplemental stimulation showed no preference between stimulus events in all testing conditions. Embryos receiving exposure to the unimodal maternal call preferred the familiar call over an unfamiliar call regardless of the presence or absence of pulsating light during testing. Embryos exposed to the call-light compound preferred the familiar call only when it was paired with the light during testing. These results suggest that concurrent multimodal stimulation does not interfere with prenatal perceptual learning by overwhelming the young organism's limited attentional capacities. Rather, multimodal stimulation biases what information is attended to during exposure and subsequent testing.     

Visuospatial attention and redundancy gain

Two experiments investigated the effect of visuospatial attention on redundancy gain in simple reaction time tasks. In each trial participants were given a central arrow cue indicating where a stimulus would most likely be presented (i.e., upper or lower half of the display in Experiment 1; left or right half of the display in Experiment 2). Then, a single stimulus or two redundant stimuli could be presented in either expected or unexpected locations. Replicating previous findings, responses were faster when stimuli appeared in expected rather than unexpected locations, and they were also faster when two redundant stimuli were presented than when only one was. Critically, redundancy gain was statistically equivalent for stimuli in expected and unexpected locations, suggesting that the effect of redundancy gain arises after the perceptual processes influenced by the allocation of visuospatial attention.

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Early visual experience affects postnatal auditory responsiveness in bobwhite quail (Colinus virginianus)

Results from 6 experiments suggest perinatal visual experience interferes with postnatal auditory responsiveness in bobwhite quail (Colinus virginianus). Light- or dark-reared control chicks responded similarly to bobwhite maternal Calls A or B following hatching. Light-reared chicks that experienced 10 min/hr of Call A or B from hatching until testing preferred the familiar call at Days 2-4, but dark-reared chicks preferred the familiar call at all ages. Increased amounts of exposure to maternal calls during postnatal Days 1-2 led to auditory responsiveness deficits in light-reared chicks. Similarly, embryos exposed to 10 min/hr of prenatal visual cues required 48 hr of postnatal Call A or B exposure to demonstrate auditory discrimination. These findings highlight the linkages between developing auditory and visual systems during infancy.     

Modification of prenatal auditory experience alters postnatal auditory preferences of bobwhite quail chicks

This study assessed the effects of altered prenatal auditory experience on bobwhite quail chicks' (Colinus virginianus) species-specific preference for the bobwhite maternal call. Results revealed that when the repetition rate of the embryonic vocalizations normally present in the prenatal environment was altered, the species-typical auditory preference of hatchlings for the maternal call was also altered. Specifically, embryos exposed to embryonic vocalizations with a faster repetition rate than normal subsequently preferred a bobwhite maternal call with a faster repetition rate over one with its normal repetition rate. Bobwhite embryos thus appear able to abstract features of their prenatal auditory environment to other auditory events in the postnatal period. This demonstration of prenatal perceptual learning is in keeping with other recent studies from behavioural embryology, which have also demonstrated that prenatal perceptual experience can influence later responses to species-typical stimulation.     

Modification of prenatal auditory experience alters postnatal auditory preferences of bobwhite quail chicks.

This study assessed the effects of altered prenatal auditory experience on bobwhite quail chicks' (Colinus virginianus) species-specific preference for the bobwhite maternal call. Results revealed that when the repetition rate of the embryonic vocalizations normally present in the prenatal environment was altered, the species-typical auditory preference of hatchlings for the maternal call was also altered. Specifically, embryos exposed to embryonic vocalizations with a faster repetition rate than normal subsequently preferred a bobwhite maternal call with a faster repetition rate over one with its normal repetition rate. Bobwhite embryos thus appear able to abstract features of their prenatal auditory environment to other auditory events in the postnatal period. This demonstration of prenatal perceptual learning is in keeping with other recent studies from behavioural embryology, which have also demonstrated that prenatal perceptual experience can influence later responses to species-typical stimulation.     

Enhanced prenatal auditory experience facilitates species-specific visual responsiveness in bobwhite quail chicks (Colinus virginianus)

Premature stimulation of a later developing sensory system is known to impact the functioning of earlier developing sensory systems. For example, exposure to premature (prenatal) visual experience results in a decline in species-typical auditory responsiveness in several precocial bird species. The present study examined the influence of experiential enhancement of an earlier developing sensory system on a later developing modality. Specifically, the influence of enhanced prenatal auditory stimulation on subsequent postnatal auditory and visual functioning of bobwhite quail (Colinus virginianus) chicks was assessed. Results indicate that birds receiving exposure to increased amounts of unaltered, species-typical embryonic vocalizations before hatching show species-typical auditory responsiveness at both 12 hr and 24 hr after hatching, but exhibit an accelerated pattern of species-typical visual responsiveness by 24 hr of age. These findings suggest that enhancement of an earlier developing sensory system can facilitate the development of a later developing sensory system and serve to demonstrate the dynamic nature of early perceptual organization.     

Algorithms and selective attention

Selective attention is hypothesized to be controlled by intentionally chosen algorithms that specify how stimuli are to be processed. These experiments attempted to measure the time to select such algorithms. Subjects were given a two-choice reaction time task with a variety of different possible stimuli. Prior to each trial, subjects viewed a cue under their control that indicated the two possible stimuli for the upcoming trial. During this interval, subjects presumably selected a stimulus identification algorithm appropriate for that pair of letters; the duration of the interval was used as an index of algorithm selection time. The results indicated that selection time increases with the number of alternative algorithms and that algorithms may consist, in part, of perceptual tests to determine which of the two possible stimuli was presented. A specific model of the selection process was proposed to account for the results.     

Increasing task difficulty enhances effects of intersensory redundancy: testing a new prediction of the Intersensory Redundancy Hypothesis

Prior research has demonstrated intersensory facilitation for perception of amodal properties of events such as tempo and rhythm in early development, supporting predictions of the Intersensory Redundancy Hypothesis (IRH). Specifically, infants discriminate amodal properties in bimodal, redundant stimulation but not in unimodal, nonredundant stimulation in early development, whereas later in development infants can detect amodal properties in both redundant and nonredundant stimulation. The present study tested a new prediction of the IRH: that effects of intersensory redundancy on attention and perceptual processing are most apparent in tasks of high difficulty relative to the skills of the perceiver. We assessed whether by increasing task difficulty, older infants would revert to patterns of intersensory facilitation shown by younger infants. Results confirmed our prediction and demonstrated that in difficult tempo discrimination tasks, 5‐month‐olds perform like 3‐month‐olds, showing intersensory facilitation for tempo discrimination. In contrast, in tasks of low and moderate difficulty, 5‐month‐olds discriminate tempo changes in both redundant audiovisual and nonredundant unimodal visual stimulation. These findings indicate that intersensory facilitation is most apparent for tasks of relatively high difficulty and may therefore persist across the lifespan.     

Age-related decrement in auditory selective attention

Young (n = 30), middle-aged (n = 32), and old (n = 28) adults repeated (shadowed) words presented to the left ear at 60 words per minute with and without distracter words presented to the other ear. Dichotic shadowing error rate increased with age. An attempt to eliminate the age effect by adjusting for age differences in monaural shadowing errors, fluid intelligence, and pure-tone hearing loss did not succeed. When the analyses were confined to subjects who made no monaural shadowing errors, dichotic shadowing errors still increased linearly with age. These results showed that there are selective-attention deficits in older adults that cannot be accounted for by the uncertainty of the target location.     

Probability matching in visual selective attention

Jonides (1980, p. 111) suggested a model to account for shifts of spatial attention in visual search tasks with less than 100% cue validity. This two-stage probability matching model was subsequently tested by Jonides (1983). Reaction time distribution characteristics indeed provided some support for the model. In the present paper the relevant data presented in Jonides (1980, 1981, 1983) are further analysed. The results of this analysis strongly support the probability matching hypothesis. Probability matching is apparently a very important strategic characteristic of visual spatial attention that deserves much more study.     

Stimules configuration in selective attention tasks

The possibility that perceptual configuration of stimulus elements impairs the ability to attend selectively to individual elements was tested with two-element stimuli, constructed by placing two curved lines in close proximity. Ss rapidly classified series of these stimuli which could differ on both elements or on only one with the second held constant. It was hypothesized that if the two elements formed a configuration, then Ss should have difficulty attending selectively to the element relevant for classification while filtering information from the other element. This result was obtained in one experiment with both stimulus elements oriented vertically, and it is concluded that these stimuli were perceived as unanalyzed, nominally related shapes. In another experiment, with one stimulus element oriented horizontally, selective attention to the relevant element was possible.     

Intersensory substitution in the blind

This study looks at the implications for theories of development of an intersensory surrogate for the blind—the Sonicguide. Results of both short- and longterm studies suggest that there is a critical age, before which use of the Sonicguide is qualitatively more effective than attempts at intervention begun after this age. Similarly the young infants in the sample show a much more rapid acquisition of ability to use the guide effectively. The importance of such results for theories of perceptual development is discussed.     

Modified prenatal sensory stimulation influences postnatal behavioral and perceptual responsiveness in bobwhite quail chicks (Colinus virginianus)

Asynchronous bimodal stimulation during prenatal development elicits higher levels of behavioral and physiological arousal in precocial avian embryos than does unimodal sensory stimulation. To investigate whether the increased arousal associated with prenatal bimodal stimulation has enduring effects into postnatal development, bobwhite quail (Colinus virginianus) embryos received no supplemental stimulation, unimodal auditory stimulation, or bimodal (audiovisual) stimulation prior to hatching. Embryos exposed to concurrent bimodal stimulation demonstrated greater levels of behavioral activity and failed to use maternal visual cues to successfully direct species-specific perceptual preferences following hatching. These results provide initial evidence that asynchronous bimodal sensory stimulation during prenatal development can have enduring effects on early postnatal behavioral arousal and perceptual responsiveness and suggest that developmental limitations on prenatal sensory stimulation play an important role in the emergence of species-typical behavior.     

Cerebral hemispheres and selective attention

The present paper is intended to discuss critically the integration model of the functional interhemispheric relation that has become dominant in neuropsychology with the development, in the last two decades, of split-brain studies.While the split-brain research has undoubtedly produced new experimental methodologies, the current theorizing in this area has been contrastingly conservative. The present paper examines some of its basic assumptions, in particular that the corpus callosum is an association pathway devoted to interhemispheric transmission of information, and that the disconnected cerebral hemispheres function in a parallel way. It is shown that these assumptions have only low consistency both with split-brain behavior and with the normal organization of the fore-brain connectivity.In the early seventies, theoretical novelty has emerged from another research field with Kinsbourne's interpretation of laterality effects in normal man. His concept of asymmetrical hemispheric arousal is shown to be supported, with some reservations, by evidence in this field. But this dynamical concept has a more general value and there are signs that current ideas about the functional relation between the cerebral hemispheres are presently deeply transformed.