Martin H. Fischer

Embodied language: A review of the role of the motor system in language comprehension

A growing body of research suggests that comprehending verbal descriptions of actions relies on an internal simulation of the described action. To assess this motor resonance account of language comprehension, we first review recent developments in the literature on perception and action, with a view towards language processing. We then examine studies of language processing from an action simulation perspective. We conclude by discussing several criteria that might be helpful with regard to assessing the role of motor resonance during language comprehension.

Perceiving numbers causes spatial shifts of attention

Number symbols are part of our everyday visual world. Here we show that merely looking at numbers causes a shift in covert attention to the left or right side, depending upon the numbers magnitude. This observation implies obligatory activation of number meaning and signals a tight coupling of internal and external representations of space.

Reading habits for both words and numbers contribute to the SNARC effect.

This study compared the spatial representation of numbers in three groups of adults: Canadians, who read both English words and Arabic numbers from left to right; Palestinians, who read Arabic words and Arabic-Indic numbers from right to left; and Israelis, who read Hebrew words from right to left but Arabic numbers from left to right. Canadians associated small numbers with left and large numbers with right space (the SNARC effect), Palestinians showed the reverse association, and Israelis had no reliable spatial association for numbers. These results suggest that reading habits for both words and numbers contribute to the spatial representation of numbers.

Unspaced text interferes with both word identification and eye movement control.

Subjects read either normal text, text in which the space information between words was absent (either spaces were removed filled with x), or text in which spaces were preserved but the words were flanked by x. In two experiments, reading rate decreased by approx. 50% when space information was not available, suggesting that reading unspaced text is relatively difficult. The removal of space information increased the effect of word frequency on the fixation times for selected target words, indicating that word identification was interfered with by the lack of spaces. In addition, removal of space information influenced the initial landing positions on words, indicating that eye movement control was affected by the absence of spaces. Further analyses were conducted that explored the relationship between these two effects.

Mindless reading revisited: Eye movements during reading and scanning are different

In an extension of a study by Vitu, O’Regan, Inhoff, and Topolski (1995), we compared global and local characteristics of eye movements during (1) reading, (2) the scanning of transformed text (in which each letter was replaced with a z), and (3) visual search. Additionally, we examined eye behavior with respect to specific target words of high or low frequency. Globally, the reading condition led to shorter fixations, longer saccades, and less frequent skipping of target strings than did scanning transformed text. Locally, the manipulation of word frequency affected fixation durations on the target word during reading, but not during visual search or z-string scanning. There were also more refixations on target words in reading than in scanning. Contrary to Vitu et al.’s (1995) findings, our results show that eye movements are not guided by a global strategy and local tactics, but by immediate processing demands.

When digits help digits: spatial-numerical associations point to finger counting as prime example of embodied cognition

Spatial–numerical associations (SNAs) are prevalent yet their origin is poorly understood. We first consider the possible prime role of reading habits in shaping SNAs and list three observations that argue against a prominent influence of this role: (1) directional reading habits for numbers may conflict with those for non-numerical symbols, (2) short-term experimental manipulations can overrule the impact of decades of reading experience, (3) SNAs predate the acquisition of reading. As a promising alternative, we discuss behavioral, neuroscientific, and neuropsychological evidence in support of finger counting as the most likely initial determinant of SNAs. Implications of this “manumerical cognition” stance for the distinction between grounded, embodied, and situated cognition are discussed.

Number processing induces spatial performance biases

Background: Response speed in parity judgments is faster with the left hand for small numbers (e.g., 1 or 2) and faster with the right hand for larger numbers (e.g., 8 or 9). This effect suggests that number processing can induce systematic spatial biases in bisection tasks. Method: Neurologically healthy participants bisected visually presented stimuli with a pencil. Stimuli were long strings of uniform digits (experiment 1) or lines with single digit flankers (experiment 2). Results: Bisection performance was biased to the left of center for strings made of digits 1 or 2 and to the right of center for strings made of digits 8 or 9. Line bisection was biased toward the flanker representing the larger magnitude, regardless of its position. Conclusions: These results extend previous findings and support the notion of an automatic association of number magnitudes with spatial response codes. The effect may be useful for an assessment of semantic number processing in special populations.

Spatial representations in number processing--evidence from a pointing task

This study investigated cognitive interactions between visuo-motor processing and numerical cognition. In a pointing task healthy participants moved their hand to a left or right target, depending on the parity of small or large digits (1, 2, 8, or 9) shown at central fixation. Movement execution was faster when left-responses were made to small digits and right-responses to large digits. These results extend the SNARC effect (spatial-numerical association of response codes) to manual pointing and support the notion of a spatially oriented mental number line.

Reading space into numbers: a cross-linguistic comparison of the SNARC effect.

Small numbers are spontaneously associated with left space and larger numbers with right space (the SNARC effect), for example when classifying numbers by parity. This effect is often attributed to reading habits but a causal link has so far never been documented. We report that bilingual Russian-Hebrew readers show a SNARC effect after reading Cyrillic script (from left-to-right) that is significantly reduced after reading Hebrew script (from right-to-left). In contrast, they have similar SNARC effects after listening to texts in either language. These results support the view that spatially directional scanning habits contribute to the spatial association of numbers but also emphasize its flexibility.

How to Cook a SNARC: Number Placement in Text Rapidly Changes Spatial-Numerical Associations.

Most theoreticians believe that reading habits explain why Western adults associate small numbers with left space and large numbers with right space (the SNARC effect). We challenge this belief by documenting, in both English and Hebrew, that SNARC changes during reading: small and large numbers in our texts appeared near the left or right ends of the lines, positioned either spatially congruent or incongruent with reading habits. In English, the congruent group showed reliable SNARC before and after reading and the incongruent groups SNARC was significantly reduced. In Hebrew the incongruent reading condition even induced a reverse SNARC. These results show that SNARC is a fleeting aspect of number representation that captures multiple spatial associations.