Why do infants make A not B errors in a search task, yet show memory for the location of hidden objects in a nonsearch task?

In 4 experiments, infants aged 8 to 12 months were tested on A not B search tasks, and nonsearch A not B tasks following the violation-of-expectation paradigm. A 1-location task and 2 control tasks were also conducted. In the nonsearch tasks, a toy was hidden in A, moved to B, and retrieved after a delay from either A (impossible) or B (possible). Results showed significantly longer looking times at impossible events, indicating some memory for where the object was hidden and an expectation of where it should be found. This effect occurred at delays at which infants made the A not B error when searching, and at a longer delay of 15 s. The results showed clearly that infants have some memory for the object's location, even at delays at which they search at the incorrect location. Discussion centers on how these results are accounted for within explanations of the A not B error. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neural correlates of cross-modal recognition memory by 8-month-old human infants.

Examined the neural correlates of cross-modal recognition memory in 8-mo-old infants by using ERPs. Testing began by having all Ss feel (but not see) an object for 60 sec. Test trials then followed. Infants in Condition 1 received 15 presentations of a picture of the familiar object, followed by alternating pictures of that object and a novel object. Infants in Condition 2 received 15 presentations of a picture of the novel object, followed by the same test sequence as infants in Condition 1. Infants in Condition 3 were presented with 2 test trials during which looking times were recorded to pictures of the familiar and novel objects; they then received the same test sequence as infants in Conditions 1 and 2. Infants in Condition 4 were presented only with the same test sequence as infants in Conditions 1, 2, and 3. Only in Conditions 1 and 4 was a late positive slow wave invoked by the novel object (indicative of recognition memory), although infants in Condition 3 did show a significant looking preference for the novel object. These results are contrasted with previous studies examining the neural correlates of visual recognition memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Action-schemes of 8-month-old infants.

Observed 64 infants, equally divided by sex and term or preterm birth, to examine the influence of preterm birth and sex on action-schemes. Both groups demonstrated the same types of action-schemes and spent similar proportions of time involved in direct object explorations. Group differences were apparent in the duration of individual action-schemes, particularly the low duration of mouthing observed with the preterm males. It is suggested that this atypical behavior in these Ss reflects a subtle aspect of behavioral disorganization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Object segregation in 8-month-old infants

Two experiments examined 8-month-old infants' use of configural and physical knowledge in segregating three-dimensional adjacent displays. The infants in Experiment I saw two identical yellow octagons standing side by side: in the test events, a hand grasped the right octagon and pulled it to the side. The infants looked reliably longer when the octagons moved apart than when they moved together, suggesting that the infants (a) perceived the octagons as a single unit and hence (b) expected them to move together and were surprised when they did not. The infants in Experiment 2 saw a yellow cylinder and a blue box: a hand grasped the cylinder and pulled it to the side. The infants looked reliably longer when the box moved with the cylinder than when the box remained in place, suggesting that they (a) viewed the cylinder and box as distinct units and thus (b) expected the cylinder to move alone and were surprised when it did not. These results indicate that, by 8 months of age, infants use configural knowledge when organizing adjacent displays: they expect similar parts to belong to the same unit and dissimilar parts to belong to distinct units. Additional results revealed that 8-month-old infants' interpretation of displays is affected not only by configural but also by physical consideration. Thus, infants in Experiment 1 who saw a thin blade lowered between the octagons viewed them as two rather than as one unit. Similarly, infants in Experiment 2 who saw the cylinder lying above instead of on the apparatus floor perceived the cylinder and box as one rather than two units. These results indicate that 8-month-old infants bring to bear their knowledge of impenetrability and support when parsing adjacent displays. Furthermore, when faced with two conflicting interpretations of a display, one suggested by their configural and one by their physical knowledge, infants allow the latter to supersede the former. Together, these findings suggest that, by 8 months of age infants approach to segregation is fundamentally similar to that of adults.     

Statistical learning by 8-month-old infants

Learners rely on a combination of experience-independent and experience-dependent mechanisms to extract information from the environment. Language acquisition involves both types of mechanisms, but most theorists emphasize the relative importance of experience-independent mechanisms. The present study shows that a fundamental task of language acquisition, segmentation of words from fluent speech, can be accomplished by 8-month-old infants based solely on the statistical relationships between neighboring speech sounds. Moreover, this word segmentation was based on statistical learning from only 2 minutes of exposure, suggesting that infants have access to a powerful mechanism for the computation of statistical properties of the language input.     

Automated gaze-contingent objects elicit orientation following in 8-month-old infants.

The current study tested whether the purely amodal cue of contingency elicits orientation following behavior in 8-month-old infants. We presented 8-month-old infants with automated objects without human features that did or did not react contingently to the infants' fixations recorded by an eye tracker. We found that an object's occasional orientation toward peripheral targets was reciprocated by a congruent visual orientation following response by infants only when it had displayed gaze-contingent interactivity. Our finding demonstrates that infants' gaze-following behavior does not depend on the presence of a human being. The results are consistent with the idea that, in 8-month-old infants, the detection of contingent reactivity, like other communicative signals, can itself elicit the illusion of being addressed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Temporal bisection in 4-month-old infants.

The present study was the first to investigate infants' ability to discriminate time using a bisection task that has been extensively used with animals and human adults. Infants aged 4 months were presented with two standard auditory signals, one short (S = 500 ms) and one long (L = 1,500 ms), and were trained either to look to the left after S and to the right after L, or vice versa. During the test phase, the infants were then presented with intermediate durations without reinforcement as well as the two reinforced standard durations, for which the reinforcement was either immediate or delayed of 3 s. The times spent by the infants looking to the right, left or away from the target after the stimulus duration were coded by two blind coders. The results revealed an orderly psychophysical function with the proportion of long responses increasing with signal duration. The point of subjective equality (Bisection Point) was closer to the geometric mean of the short and long standard duration than to their arithmetic mean. Modeling using the scalar timing models revealed that our infants had a relatively high sensitivity to time but that their temporal performance was affected by the fact that they made a large number of random responses. The development of the perception of time is discussed in the light of similarities and differences in temporal bisection performance between different species (rats and humans) and the different levels of development observed within a given species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cross-modal transfer in 6-month-old infants.

Investigated in 4 studies with 101 infants 25.5–32 wks of age the ability of Ss to transfer information about shape across modalities. Ss were familiarized either orally or tactually and then tested for visual recognition memory. In Exp I, Ss failed to show evidence of cross-modal transfer on any of the tasks (1 oral–visual, 2 tactual–visual). When familiarization times were increased from 30 to 60 sec in Exp II, Ss showed evidence of transfer on both tactual–visual tasks. Exp III eliminated the 5–7 sec delay that generally intervenes between the familiarization and test phase. Ss were permitted to retain the stimulus in their hand (or mouth) during the test phase while simultaneously viewing a novel stimulus and a duplicate of the familiar stimulus. This modification resulted in successful transfer on 1 of the 2 tactual–visual tasks. Ss did not show evidence of transfer on the oral–visual problem in any of these studies, despite evidence from Exp IV that they could visually discriminate the paired stimuli used in these tasks and that they showed recognition memory when familiarization and testing were both visual. Results suggest that, although cross-modal transfer of information about shape is present among 6-mo-olds, it is a less robust phenomenon than that seen in older infants. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evidence from a partial report task for forgetting in dynamic spatial memory

G. Sperling (1960) and others have investigated memory for briefly presented stimuli by using a partial versus whole report technique in which participants sometimes reported part of a stimulus array and sometimes reported all of it. For simple, static stimulus displays, the partial report technique showed that participants could recall most of the information in the stimulus array but that this information faded quickly when participants engaged in whole report recall. An experiment was conducted that applied the partial report method to a task involving complex displays of moving objects. In the experiment, 26 participants viewed cars in a low-fidelity driving simulator and then reported the locations of some or all of the cars in each scene. A statistically significant advantage was found for the partial report trials. This finding suggests that detailed spatial location information was forgotten from dynamic spatial memory over the 14 s that it took participants to recall whole report trials. The experiment results suggest better ways of measuring situation awareness. Partial report recall techniques may give a more accurate measure of people's momentary situation awareness than whole report techniques. Potential applications of this research include simulator-based measures of situation awareness ability that can be part of inexpensive test batteries to select people for real-time tasks (e.g., in a driver licensing battery) and to identify people who need additional training.     

Working memory and the control of action: Evidence from task switching.

A series of 7 experiments used dual-task methodology to investigate the role of working memory in the operation of a simple action-control plan or program involving regular switching between addition and subtraction. Lists requiring switching were slower than blocked lists and showed 2 concurrent task effects. Demanding executive tasks impaired performance on both blocked and switched lists, whereas articulatory suppression impaired principally the switched condition. Implications for models of task switching and working memory and for the Vygotskian concept of verbal control of action are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perception of object unity in 2-month-old infants.

The perception of object unity in partial occlusion displays was examined in 72 2-month-old infants. The infants were habituated to 1 of 3 displays depicting a rod undergoing lateral motion behind a box. In each display, more of the rod was visible behind the box than was previously available in prior studies of young infants' perception of occlusion. Posthabituation test displays consisted of 2 rod pieces (broken rod) and a complete rod, presented 3 times each in alternation. Infants in all 3 conditions looked longer at the broken rod than at the complete rod, suggesting that the hidden region of the rod in the habituation display was inferred despite the absence of direct perceptual support. These findings suggest that very young infants' visual, attentional, or cognitive skills may be insufficient to consistently support perception of object unity, except under some display conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detection of stimulus motion in 5-month-old infants.

Five-month-old infants were tested by the method of preferential looking for discrimination between a pattern undergoing oscillating apparent motion and an identical static pattern. Sensitivity to small spatial displacements was evident at temporal frequencies of 8 and 16 Hz. Preference for the moving display was related independently to the temporal frequency of oscillation and the magnitude of the spatial displacement. Preferences for the moving display increased asymptotically across spatial displacements from 11 to 89 arc min. Preferences peaked between temporal oscillation frequencies of 8 and 16 Hz. Preference was not related to the ratio of these two variables—velocity. The minimum displacement threshold of 7.36 arc min was found to depend on the size of the elements in the pattern and on the temporal frequency of oscillation. The results demonstrate that motion-sensitive mechanisms responsive to small spatial displacements are present at 5 months of age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prospective memory and task interference in a continuous monitoring dynamic display task.

Theories and methods from the prospective memory literature were used to anticipate how individuals would maintain and retrieve intentions in a continuous monitoring dynamic display task. Participants accepted aircraft into sectors and detected aircraft conflicts during an air traffic control simulation. They were sometimes required to substitute new actions for routine actions when accepting aircraft traveling at certain speeds or altitudes, or with certain call signs. In Experiment 1, prospective memory error increased with intent to deviate from strong compared to weak routine, and this effect was larger for altitude intentions compared to speed intentions. In addition, errors increased when intentions were general compared to specific. Participants also missed more conflicts when deviating from strong compared to weak routine. In Experiment 2, errors increased for intentions nonfocal to ongoing tasks compared to focal, and this effect was larger for altitude intentions compared to call sign intentions. Participants were slower to accept aircraft when holding nonfocal compared to focal intentions, and slower to accept aircraft and detect conflicts when holding focal intentions compared to no intentions. These findings are consistent with theories that assume that individuals allocate limited-capacity attentional resources to prospective memory tasks. Increased error for altitude intentions, together with the effect of routine strength, suggest a vulnerability to error with increased strength of association between prospective memory cues and competing ongoing tasks. Ongoing tasks that focus attention on cues may sometimes impair, rather than benefit, intention retrieval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Event-related brain potentials during an extended visual recognition memory task depict delayed development of cerebral inhibitory processes among 6-month-old infants with Down syndrome

Development of cerebral inhibitory processes among individuals with Down syndrome (DS) may be delayed at an early age. In support of this hypothesis, sensory-evoked potentials (EPs) and event-related brain potentials (ERPs) have previously delineated altered habituation to stimuli among infants with DS. The purpose of the current study was to provide extended experience with visual stimuli among 6-month-old infants with and without DS (nDS) to determine if altered ERP and behavioral response decrements would be evident even after repeated presentations of stimuli. An 80/20% oddball paradigm was employed. Infants with DS and nDS were matched according to age and gender. Infants with DS demonstrated significantly larger Nc areas, Nc peak amplitudes, Nc2 areas and, inversely, significantly smaller peak Pb amplitudes when compared to infants nDS. Contrasts of the two study groups were most robust within ERP measures from frontal (Fz) and parietal (Pz) recording sites. Infants with DS also demonstrated a significantly slower decrement of most ERP components with repetitive stimulus experience. Most noteworthy was the observation of little or no decrement of ERP components at Fz among infants with DS. Both infants with DS and nDS demonstrated significantly larger Nc peak amplitudes, Nc areas, Nc2 areas, Pb peak amplitudes and NSW areas to rare stimuli. While significant probability and experiential trends were observed in visual fixation measures across both study groups, there were no significant differences of visual attention between infants with DS or nDS. These data demonstrate the value of ERPs within the study of atypical cognitive development during infancy and support the concept of altered inhibitory processes in the brain of infants with DS.     

Long-term recognition memory for faces assessed by visual paired comparison in 3- and 6-month-old infants.

It has been argued that operant conditioning is the only type of long-term memory present in infants prior to 6 months of age. In this study, memory for faces was investigated in 3- and 6-month-old infants with a visual paired-comparison task. In Experiment 1, infants were habituated to a face presented in different poses; recognition was assessed after a 2-min or a 24-hr retention interval. The 6-month-old infants and the male but not the female 3-month-old infants exhibited novelty preferences. A 2nd experiment showed that 3-month-old female infants were delayed relative to male infants in their face-processing ability rather than in their memory capacity. The results of Experiment 3 demonstrated in 3-month-olds an electrophysiological correlate of delayed recognition memory. These findings are discussed in the context of the neural systems thought to be involved in visual recognition memory (but not in procedural memory), namely the limbic system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Similarities and differences between working memory and long-term memory: Evidence from the levels-of-processing span task.

Two experiments compared the effects of depth of processing on working memory (WM) and long-term memory (LTM) using a levels-of-processing (LOP) span task, a newly developed WM span procedure that involves processing to-be-remembered words based on their visual, phonological, or semantic characteristics. Depth of processing had minimal effect on WM tests, yet subsequent memory for the same items on delayed tests showed the typical benefits of semantic processing. Although the difference in LOP effects demonstrates a dissociation between WM and LTM, we also found that the retrieval practice provided by recalling words on the WM task benefited long-term retention, especially for words initially recalled from supraspan lists. The latter result is consistent with the hypothesis that WM span tasks involve retrieval from secondary memory, but the LOP dissociation suggests the processes engaged by WM and LTM tests may differ. Therefore, similarities and differences between WM and LTM depend on the extent to which retrieval from secondary memory is involved and whether there is a match (or mismatch) between initial processing and subsequent retrieval, consistent with transfer-appropriate-processing theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automatic activation of episodic information in a semantic memory task.

Conducted 4 experiments with 122 undergraduates to examine priming between newly learned associates and priming between well-known associates in lexical decision. All experiments showed that priming occurred between newly learned associates, including conditions in which the stimulus onset asynchrony (SOA) between prime and target was short (150 msec) and in which the probability was low (1/12) that the prime and target of a pair would be associated to each other. It is concluded, contrary to suggestions by M. Carroll and K. Kirsner (see record 1982-25008-001) and E. Tulving (1983), that newly learned associates can prime each and that they can do so at short SOAs. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bisensory response to temporal frequency in 4-month-old infants.

Three studies investigated detection of auditory–visual equivalence of rate among 55 4-mo-olds. In the 1st 2 studies, Ss were shown pairs of check patterns flashing at 2, 4, and 8 Hz either in silence or while listening to a tone corresponding in rate to 1 member of the pair. In Study 1, rate of stimulation varied, whereas duty cycle (i.e., intensity) was kept constant. No evidence of bisensory matching of rate was found. In Study 2, rate and duty cycle covaried. Although no matching was found, the presence of the 2 most intense sounds led to a shift in looking toward lower rates of visual stimulation. In Study 3, rate was kept constant (2 Hz), whereas duty cycle was varied. No matching was found, but as in Study 2, the presence of the most intense sound led to a shift in looking toward the less intense visual stimuli. Although these findings are contrary to previous reports of auditory–visual matching of rate, they do indicate that sound influences visual preferences via an intensity-based response mechanism. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infant-directed speech drives social preferences in 5-month-old infants.

Adults across cultures speak to infants in a specific infant-directed manner. We asked whether infants use this manner of speech (infant- or adult-directed) to guide their subsequent visual preferences for social partners. We found that 5-month-old infants encode an individual's use of infant-directed speech and adult-directed speech, and use this information to guide their subsequent visual preferences for individuals even after the speech behavior has ended. Use of infant-directed speech may act as an effective cue for infants to select appropriate social partners, allowing infants to focus their attention on individuals who will provide optimal care and opportunity for learning. This selectivity may play a crucial role in establishing the foundations of social cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)