RESUMEN

Immediate serial recall of visually presented items is reliably impaired by task-irrelevant speech that the participants are instructed to ignore ("irrelevant speech effect," ISE). The ISE is stronger with changing speech tokens (words or syllables) when compared to repetitions of single tokens ("changing-state effect," CSE). These phenomena have been attributed to sound-induced diversions of attention away from the focal task (attention capture account), or to specific interference of obligatory, involuntary sound processing with either the integrity of phonological traces in a phonological short-term store (phonological loop account), or the efficiency of a domain-general rehearsal process employed for serial order retention (changing-state account). Aiming to further explore the role of attention, phonological coding, and serial order retention in the ISE, we analyzed the effects of steady-state and changing-state speech on serial order reconstruction of visually presented verbal and spatial items in children (n = 81) and adults (n = 80). In the verbal task, both age groups performed worse with changing-state speech (sequences of different syllables) when compared with steady-state speech (one syllable repeated) and silence. Children were more impaired than adults by both speech sounds. In the spatial task, no disruptive effect of irrelevant speech was found in either group. These results indicate that irrelevant speech evokes similarity-based interference, and thus pose difficulties for the attention-capture and the changing-state account of the ISE.

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RESUMEN

Our ability to retain visuospatial information over brief periods of time is severely limited and develops gradually. In childhood, visuospatial short-term and working memory are typically indexed using span-based measures. However, whilst these standardized measures have been successful in characterizing developmental and individual differences, each individual trial only provides a binary measure of a child's performance-they are either correct or incorrect. Here we used a novel continuous report paradigm, in combination with probabilistic modeling, to explore developmental and individual differences in how likely children were to recall memoranda, and how precisely they could report them. Taking this approach revealed a number of novel findings: (i) a concurrent processing demand negatively impacted upon both of these parameters, increasing the guessing rate and making children less precise; (ii) older children (aged 10-12, N = 20) were significantly less likely to guess, but when they did remember the target were no more precise in reporting it than younger children (aged 7-9, N = 20); (iii) children's performance on standardized short-term and working memory tasks was significantly associated with both the guessing likelihood, and the precision of target responding, on the continuous report task. In short, we show that continuous report paradigms can offer interesting insight into processes that underlie developmental and individual differences in visuospatial memory in childhood.

RESUMEN

Cerebral asymmetries and cortical regions associated with the upper and lower visual field were investigated using shifts of gaze. Earlier research suggests that gaze shifts to the left or right increase activation of specific areas of the contralateral hemisphere. We asked whether looking at one quadrant of the visual field facilitates the recall in various visuo-spatial tasks. The different components of visuo-spatial memory were investigated by probing memory for a stimulus matrix in each quadrant of the screen. First, memory for visual images or patterns was probed with a matrix of squares that was simultaneously presented and had to be reconstructed by mouse click. Better memory performance was found in the upper left quadrant compared to the three other quadrants indicating that both laterality and elevation are important. Second, positional memory was probed by subsequently presenting squares which prevented the formation of a visual image. Again, we found that gaze to the upper left facilitated performance. Third, memory for object-location binding was probed by asking observers to associate objects to particular locations. Higher performance was found with gaze directed to the lower quadrants irrespective of lateralization, confirming that only some components of visual short-term memory have shared neural substrates.

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RESUMEN

Hemispheric asymmetries were investigated by changing the horizontal position of stimuli that had to be remembered in a visuo-spatial short-term memory task. Observers looked at matrices containing a variable number of filled squares on the left or right side of the screen center. At stimulus offset, participants reproduced the positions of the filled squares in an empty response matrix. Stimulus and response matrices were presented in the same quadrant. We observed that memory performance was better when the matrices were shown on the left side of the screen. We distinguished between recall strategies that relied on visual or non-visual (verbal) cues and found that the effect of gaze position occurred more reliably in participants using visual recall strategies. Overall, the results show that there is a solid enhancement of visuo-spatial short-term memory when observers look to the left. In contrast, vertical position had no influence on performance. We suggest that unilateral gaze to the left activates centers in the right hemisphere contributing to visuo-spatial memory.

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