Mental representations of arithmetic facts: Evidence from eye movement recordings supports the preferred operand-order-specific representation hypothesis

There are three main hypotheses about mental representations of arithmetic facts: the independent representation hypothesis, the operand-order-free single-representation hypothesis, and the operand-order-specific single-representation hypothesis. The current study used electrical recordings of eye movements to examine the organization of arithmetic facts in long-term memory. Subjects were presented single-digit addition and multiplication problems and were asked to report the solutions. Analyses of the horizontal electrooculograph (HEOG) showed an operand order effect for multiplication in the time windows 150–300 ms (larger negative potentials for smaller operand first problems than for larger operand first ones). The operand order effect was reversed in the time windows from 400 to 1,000 ms (i.e., larger operand first problems had larger negative potentials than smaller operand first problems). For addition, larger operand first problems had larger negative potentials than smaller operand first in the series of time windows from 300 to 1,000 ms, but the effect was smaller than that for multiplication. These results confirmed the dissociated representation of addition and multiplication facts and were consistent with the prediction of the preferred operand-order-specific representation hypothesis.     

Eye movements and parafoveal preview of compound words: Does morpheme order matter?

Recently, there has been considerable debate about whether readers can identify multiple words in parallel or whether they are limited to a serial mode of word identification, processing one word at a time (see, e.g., Reichle, Liversedge, Pollatsek, & Rayner, 2009). Similar questions can be applied to bimorphemic compound words: Do readers identify all the constituents of a compound word in parallel, and does it matter which of the morphemes is identified first? We asked subjects to read compound words embedded in sentences while monitoring their eye movements. Using the boundary paradigm (Rayner, 1975), we manipulated the preview that subjects received of the compound word before they fixated it. In particular, the morpheme order of the preview was either normal (cowboy) or reversed (boycow). Additionally, we manipulated the preview availability for each of the morphemes separately. Preview was thus available for the first morpheme only (cowtxg), for the second morpheme only (enzboy), or for neither of the morphemes (enztxg). We report three major findings: First, there was an effect of morpheme order on gaze durations measured on the compound word, indicating that, as expected, readers obtained a greater preview benefit when the preview presented the morphemes in the correct order than when their order was reversed. Second, gaze durations on the compound word were influenced not only by preview availability for the first, but also by that for the second morpheme. Finally, and most importantly, the results show that readers are able to extract some morpheme information even from a reverse order preview. In summary, readers obtain preview benefit from both constituents of a short compound word, even when the preview does not reflect the correct morpheme order.     

Timing is everything: Changes in presentation rate have opposite effects on auditory and visual implicit statistical learning

Implicit statistical learning (ISL) is exclusive to neither a particular sensory modality nor a single domain of processing. Even so, differences in perceptual processing may substantially affect learning across modalities. In three experiments, statistically equivalent auditory and visual familiarizations were presented under different timing conditions that either facilitated or disrupted temporal processing (fast or slow presentation rates). We find an interaction of rate and modality of presentation: At fast rates, auditory ISL was superior to visual. However, at slow presentation rates, the opposite pattern of results was found: Visual ISL was superior to auditory. Thus, we find that changes to presentation rate differentially affect ISL across sensory modalities. Additional experiments confirmed that this modality-specific effect was not due to cross-modal interference or attentional manipulations. These findings suggest that ISL is rooted in modality-specific, perceptually based processes.     

The approximate number system is not predictive for symbolic number processing in kindergarteners

The relation between the approximate number system (ANS) and symbolic number processing skills remains unclear. Some theories assume that children acquire the numerical meaning of symbols by mapping them onto the preexisting ANS. Others suggest that in addition to the ANS, children also develop a separate, exact representational system for symbolic number processing. In the current study, we contribute to this debate by investigating whether the nonsymbolic number processing of kindergarteners is predictive for symbolic number processing. Results revealed no association between the accuracy of the kindergarteners on a nonsymbolic number comparison task and their performance on the symbolic comparison task six months later, suggesting that there are two distinct representational systems for the ANS and numerical symbols.     

Parallel processing of whole words and morphemes in visual word recognition

Models of morphological processing make different predictions about whether morphologically complex written words are initially decomposed and recognized on the basis of their morphemic subunits or whether they can directly be accessed as whole words and at what point semantics begin to influence morphological processing. In this study, we used unprimed and masked primed lexical decision to compare truly suffixed (darkest) and pseudosuffixed words (glossary) with within-boundary (d ra kest/g ol ssary) to across-boundary (dar ek st/glos as ry) letter transpositions. Significant transposed-letter similarity effects were found independently of the morphological position of the letter transposition, demonstrating that, in English, morphologically complex whole-word representations can be directly accessed at initial word processing stages. In a third masked primed lexical decision experiment, the same materials were used in the context of stem target priming, and it was found that truly suffixed primes facilitate the recognition of their stem-target (darkest–DARK) to the same extent as pseudosuffixed primes (glossary–GLOSS), which is consistent with theories of early morpho-orthographic decomposition. Taken together, our findings provide evidence for both whole-word access and morphological decomposition at initial stages of visual word recognition and are discussed in the context of a hybrid account.     

Left–right holistic integration of human bodies

Holistic integration of faces has been widely studied. More recently, investigations have explored whether similar processing is used for human bodies. Here we show that holistic processing, as measured by the composite task, does occur for bodies but is stronger for left and right halves than for top and bottom halves. We also found composite effects for left–right halves of inverted bodies. Standard composite effects were found for top halves of faces, tested as a control. We argue that our results suggest that holistic processing of faces and bodies might not exclusively occur for identification, but instead may also have evolved to aid communication and/or decisions about mate choice (through judging symmetry).     

Numerical and physical magnitudes are mapped into time

In two experiments we investigated mapping of numerical and physical magnitudes with temporal order. Pairs of digits were presented sequentially for a size comparison task. An advantage for numbers presented in ascending order was found when participants were comparing the numbers' physical and numerical magnitudes. The effect was more robust for comparisons of physical size, as it was found using both select larger and select smaller instructions, while for numerical comparisons it was found only for select larger instructions. Varying both the digits' numerical and physical sizes resulted in a size congruity effect, indicating automatic processing of the irrelevant magnitude dimension. Temporal order and the congruency between numerical and physical magnitudes affected comparisons in an additive manner, thus suggesting that they affect different stages of the comparison process.     

On the time course of exogenous cueing effects in bilinguals: Higher proficiency in a second language is associated with more rapid endogenous disengagement

Previous investigations have demonstrated a bilingual advantage on various aspects of executive control. It remains unclear how the language proficiency of bilinguals might relate to the mechanisms involved in attentional disengagement. In the present investigation, we tested the hypothesis that high bilingual proficiency would lead to a more rapid endogenous disengagement of attention from task-irrelevant peripheral cues. We predicted that more rapid attentional disengagement would result in an earlier appearance of inhibition of return (IOR). In this study Hindi–English bilinguals who differed in their L2 (English) proficiency participated in a target detection task. Visual targets were preceded by uninformative peripheral cues at various stimulus onset asynchronies (SOAs) allowing for us to visualize the time course of cue-related facilitation and inhibition. High-proficient Hindi–English bilinguals showed an earlier appearance of IOR than did low-proficient bilinguals, suggesting increased efficiency in disengagement of attention from task-irrelevant inputs. Furthermore, consistent with the “global” advantage that characterizes bilinguals in many tasks, the high-proficient group outperformed low-proficient bilinguals in overall reaction time.     

The role of visual spatial attention in adult developmental dyslexia

The present study investigated the nature of visual spatial attention deficits in adults with developmental dyslexia, using a partial report task with five-letter, digit, and symbol strings. Participants responded by a manual key press to one of nine alternatives, which included other characters in the string, allowing an assessment of position errors as well as intrusion errors. The results showed that the dyslexic adults performed significantly worse than age-matched controls with letter and digit strings but not with symbol strings. Both groups produced W-shaped serial position functions with letter and digit strings. The dyslexics' deficits with letter string stimuli were limited to position errors, specifically at the string-interior positions 2 and 4. These errors correlated with letter transposition reading errors (e.g., reading slat as “salt”), but not with the Rapid Automatized Naming (RAN) task. Overall, these results suggest that the dyslexic adults have a visual spatial attention deficit; however, the deficit does not reflect a reduced span in visual–spatial attention, but a deficit in processing a string of letters in parallel, probably due to difficulty in the coding of letter position.