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.     

Fearful expressions enhance recognition memory: electrophysiological evidence

Facial expressions play a key role in affective and social behavior. However, the temporal dynamics of the brain responses to emotional faces remain still unclear, in particular an open question is at what stage of face processing expressions might influence encoding and recognition memory. To try and answer this question we recorded the event-related potentials (ERPs) elicited in an old/new recognition task. A novel aspect of the present design was that whereas faces were presented during the study phase with either a happy, fearful or neutral expression, they were always neutral during the memory retrieval task. The ERP results showed three main findings: An enhanced early fronto-central positivity for faces encoded as fearful, both during the study and the retrieval phase. During encoding subsequent memory (Dm effect) was influenced by emotion. At retrieval the early components P100 and N170 were modulated by the emotional expression of the face at the encoding phase. Finally, the later ERP components related to recognition memory were modulated by the previously encoded facial expressions. Overall, these results suggest that face recognition is modulated by top-down influences from brain areas associated with emotional memory, enhancing encoding and retrieval in particular for fearful emotional expressions.     

The speed of visual recognition memory

Two processes are thought to support visual recognition memory (VRM): Familiarity and recollection. The former is generally considered to be faster. However, the relationship between the precise onset of the two processes is unclear. Here, we use a novel paradigm, the SAB (Speed and Accuracy Boosting procedure) that constrains participants to use their fastest strategy and provides a continuous distribution of their reaction times. We show that fast recognition occurs as early as ~370 ms, a limit that appears incompressible whatever types of stimuli were used. In a second experiment, running the SAB in conjunction with a modified version of the remember/know paradigm, we show that responses up to ~420 ms are based solely on familiarity. These time limits of 370 ms and 420 ms provide strong constraints on the neural mechanisms underlying VRM and suggest that the fastest, familiarity-based, responses could rely on the visual ventral stream only.     

Reproduction and recognition in short-term visual memory

Reproduction and recognition in short-term visual memory was tested. In Experiment I, it was confirmed that the ability to reproduce visual figures in STM correlated with the ability to describe them. No such correlation was obtained when recall was by recognition. In Experiments II and III the mechanisms involved in the two types of recall were investigated by varying the character of the task interpolated in the retention interval. Results support the view that reproduction has a verbal component which is lacking in recognition.     

An analysis of the visual component in recognition memory for verbal stimuli

Forty Ss were given a continuous recognition memory test in which each word was presented twice, either in the same print or in different print on the two occasions. The results showed that (a) recognition performance was facilitated to a small but statistically significant extent in the same-print condition and that (b) Ss could reliably report first presentation print for recognized items for at least 1^1/2 rain. In a second experiment, the stimuli used were nonsense strings of. from five to seven letters instead of words. This manipulation increased the same-print advantage in recognition but reduced Ss’ ability to report first print form. The results indicate that information about the physical features of verbal stimuli is retained in a visual code that is partially’ or wholly independent of the verbal code for the same stimuli. The results are inconsistent with the conclusion that the visual code is stored only as a dependent attribute of the verbal code in memory.     

An electrophysiological model of working memory performance

Working memory (WM) enables us to keep a limited amount of information in active mode. It is believed that attention refreshes necessary information in WM and prevents their forgetting. Despite a plethora of models offered, it is not fully understood that what factors may be involved in forgetfulness and in the required time for refreshing the information. In this study, an electrophysiological model of WM is proposed that consists of several resistor-capacitor units. Inspired of the “resource capacity theory,” attention as a limited source of energy refreshes the voltage level of these units. According to the “time-based resource sharing theory,” only one of these units is allowed to use the limited source of attention at each moment. The source of attention is shared between active units. This model mimics the pattern of several well-known observations of WM such as the recall interval, the word length, and the serial position effect. Some suggestions have been provided about influencing factors in WM performance. Model parameters give the ability of investigating the possible effect of some other factors on WM performance and also a probable prediction about how much information can we chunk?     

Multifactorial context effects on visual recognition memory

While effects of contextual change or constancy on memory are widely found when tested by free and cued recall, there is greater inconsistency in context effects on recognition. This study employed a paradigm maximizing target-context interactivity and specificity to reveal three levels of context effects on successful retrieval, as well as context effects on the generation of false alarms, thereby revealing separable contributions of target-context binding, additive familiarity, and configural constancy. The separability of these factors enables the use of memory context effects as tools for investigating associative memory.     

Multifactorial context effects on visual recognition memory

While effects of contextual change or constancy on memory are widely found when tested by free and cued recall, there is greater inconsistency in context effects on recognition. This study employed a paradigm maximizing target–context interactivity and specificity to reveal three levels of context effects on successful retrieval, as well as context effects on the generation of false alarms, thereby revealing separable contributions of target–context binding, additive familiarity, and configural constancy. The separability of these factors enables the use of memory context effects as tools for investigating associative memory.     

An electrophysiological model of human visual reaction time

Human visual reaction times were fractionated into component latencies measuring visual reception time, opto-motor integration time, central motor outflow time, and peripheral motor time on the basis of evoked cortical activity recorded from the intact scalp and the occurrence of the response electromyogram. Normative data are presented for a right-foot dorsiflexion task studied on 18 male subjects, together with an analysis of inter- and intra-subject variability in response timing. Faster reactors were found to display briefer opto-motor integration times and motor times, while an individual's faster responses were characterized by shorter motor outflow times and motor time. These results are interpreted in terms of varying physiological mechanisms.     

Reported visual imagery for faces and facial recognition memory

Data from several studies of college students yielded moderate correlations among faces recognition scores (ratings, answers to questions), but association between visual imagery and recognition memory for faces was small to medium. Women reported more vivid and better controlled visual imagery for faces than men.     

The effect of mood-context on visual recognition and recall memory

Although it is widely known that memory is enhanced when encoding and retrieval occur in the same state, the impact of elevated stress/arousal is less understood. This study explores mood-dependent memory's effects on visual recognition and recall of material memorized either in a neutral mood or under higher stress/arousal levels. Participants' (N = 60) recognition and recall were assessed while they experienced either the same o a mismatched mood at retrieval. The results suggested that both visual recognition and recall memory were higher when participants experienced the same mood at encoding and retrieval compared with those who experienced a mismatch in mood context between encoding and retrieval. These findings offer support for a mood dependency effect on both the recognition and recall of visual information.     

Development of flexible visual recognition memory in human infants

Research using the visual paired comparison task has shown that visual recognition memory across changing contexts is dependent on the integrity of the hippocampal formation in human adults and in monkeys. The acquisition of contextual flexibility may contribute to the change in memory performance that occurs late in the first year of life. To assess this skill, the images are presented on a background of one colour during familiarization and on a different coloured background during the recognition test. Our research showed that recognition memory is impaired by a change in context at 6 and 12 months of age but is unaffected at 18 and 24 months of age. The findings are discussed in relation to hippocampal development and the proposed developmental step in memory at 9-10 months of age.     

Infants' recognition memory for a series of visual stimuli

The tendency of infants to distribute attention selectively to novel and familiar visual stimuli was employed to study infants' recognition memory for a series of visual targets. Infants 5 months of age demonstrated an unequal distribution of visual fixation to novel and familiar stimuli, with more attention to the novel, on both immediate and delayed stimulus-recognition tests for each of three novelty problems administered during a single testing session. The degree of differential fixation to novel targets exhibited no reliable decline from immediate to delayed testing and was not significantly altered by the serial order which the problem occupied during immediate recognition testing.     

The relation between lisping and visual recognition memory in children

It was argued that if silent reading involves articulatory coding then children with a pronounced lisp ought to code two visual nonsense words such as RETH and RESS more similarly than children without a lisp. This, in tum, would lead to more false positives in a recognition memory task. Although the data confirmed this hypothesis, it turned out that lisping children made more correct positives (hits) as well. Lisping and normal children did not differ in sensitivity (d^′); therefore, the main result was a difference in criterion. An implausible hypothesis was offered so as to salvage a portion of the original argument.     

Infant visual recognition memory: independent contributions of speed and attention

Relations between infant visual recognition memory and later cognition have fueled interest in identifying the underlying cognitive components of this important infant ability. The present large-scale study examined three promising factors in this regard--processing speed, short-term memory capacity, and attention. Two of these factors, attention and processing speed (but, surprisingly, not short-term memory capacity), were related to visual recognition memory: Infants who showed better attention (shorter looks and more shifts) and faster processing had better recognition memory. The contributions of attention and processing speed were independent of one another and were similar at all ages studied--5, 7, and 12 months. Taken together, attention and speed accounted for 6%-9% of the variance in visual recognition memory, leaving a considerable, but not unexpected, portion of the variance unexplained.     

Identification and categorization in visual search

Seven experiments were addressed to the general question of whether the identification of letters and numbers is a more rapid process than the categorization of such stimuli. Subjects were required to make a single response if a target stimulus specified by name (e.g., “A,” “2”) or designated by category class alone (e.g., “letter,” “number”) was presented in a trial. The principal findings were: (1) identification reaction times (RTs) were faster than categorization RTs: (2) RTs for targets shown without a context were faster than RTs for targets shown in the context of other stimuli; (3) identification RTs for targets shown in the context of stimuli from a different conceptual-taxonomic category were faster than RTs for targets shown in the context of stimuli from the same category only when target-context stimulus discriminability differencet were optimized. The results were interpreted in terms of a two-stage processing model in which context face,ors affect the duration of an initial encoding-scanning stage and search instruction (effective memory size) factors affect the duration of the memory comparison stage.     

An experimental study of visual imagination and memory

It is shown that an irrelevant visual perception interferes more with verbal learning by means of imagery than does an irrelevant auditory perception. The relative interfering effects of these perceptions were reversed in a verbal learning task involving highly abstract materials. Such results implicate the existence of a true visual component in imaginal mediation. A theoretical model is presented in which a visual system and a verbal-auditory system are distinguished. The visual system controls visual perception and visual imagination. The verbal-auditory system controls auditory perception, auditory imagination, internal verbal representation, and speech. Attention can be more easily divided between the two systems than within either one taken by itself. Furthermore, the visual and verbal-auditory systems are functionally linked by information recoding operations. The application of mnemonic imagery appears to involve a recoding of initially verbal information into visual form, and then the encoding of a primarily visual schema into memory. During recall, the schema is decoded as a visual image, and then recoded once again into the verbal-auditory system. Evidence for such transformations is provided not only by the interference data, but also by an analysis of recall-errors made by Ss using mnemonic imagery.