When we refer to spatial arrangements in language, there are three different ways to do it. We can see ourselves as central and refer to the positions of other objects by their headings from us. So, that post is behind me or that house is to my left – relative or egocentric frame. We can also see some other object as the reference. So, that post is behind the house or the garden is on the left of the car – intrinsic or object oriented frame. Finally we can use the world as the reference. So, the post is to the west of the house – absolute or world oriented frame. How people handle the choice of referent is largely a matter of culture and language. European languages mainly use a relative frame of reference as default – we are usually the reference. But there is often room for ambiguity. Does the “the ball is in front of the man” mean it that the ball is between me and the man or does it mean that the man is facing the ball? This interests me in particular because I often seem to misinterpret what is meant or am left wondering. In the past, I have put it down to being left-handed.
Janzen, Haum and Levinson (see citation) investigated relative and intrinsic using the possibilities of ambiguity. They created sentences like “the ball is in front of the man” and three drawings to go with the sentence. One drawing would be true in both relative and intrinsic interpretations; one would be false for both; one would be true for one interpretation and false for the other. They showed a picture and sentence and asked the subject to say whether the drawing was a correct description of the sentence. The subjects were given feedback on whether their answers were correct. This feedback was either based on the relative or the intrinsic interpretation and the subjects came to judge the sentence-drawing pairs according to the feedback type they were receiving. During a block of trials, consistent feedback (correct, incorrect) was given so inducing either a relative or intrinsic frame. Midway through the trials, the second block began and the feedback was switched to the alternative reference frame without any explanation . Only correct answers were used in the analysis. This gave results for identical sentence-drawing pairs viewed in each of the two frames of reference. The subjects spoke Dutch which tends to use relative reference. Event-related fMRI was used to follow the differences in cortical activity in the two reference frames following identical linguistic and visual input.
They found two networks, an intrinsic one and a relative one. The differentiation starts early at the level of sentence processing (that is before the drawing is shown and the answer required). Increased brain activity in bilateral parahippocampal gyrus was associated with the intrinsic frame of reference whereas increased activity in the right superior frontal gyrus and in the parietal lobe was observed for the relative frame of reference.
Comparing trials with intrinsic as well as relative pictures to baseline trials we found a shared widespread network with increased activity in occipital, parietal, temporal and frontal brain regions. This is in line with evidence from an fMRI study that distinguished viewer-, object-, and landmark-centered distance judgments, and found common activity for all three types in bilateral parietal, occipital, and right frontal premotor regions as well.
In the present study we directly compared intrinsic with relative trials and observed increased activity for intrinsic trials in bilateral parahippocampal gyrus, an area closely connected to the hippocampus through the entorhinal and perirhinal gyrus. Recent neuroimaging studies emphasize the importance of the parahippo-campal gyrus for the recognition of familiar as well as novel spatial environments and scenes and for object-location memory . To correctly solve intrinsic trials participants needed to consider the spatial relation of two objects and decide whether the scene matched a previously presented sentence. Therefore scene representation within the parahippocampal gyrus should be able to support intrinsic frames of reference.
fMRI data has shown that the parietal lobe is associated with representations of object locations in an egocentric reference frame. The present data when comparing relative trials to baseline trials supports the involvement of the parietal lobe. We observed increased activity in the left parietal lobe for the relative frame of reference only, confirming neurophysiological studies which report the involvement of the parietal lobe in egocentric coding.
Relative trials as compared to intrinsic trials also showed strongly increased activity in superior frontal gyrus. This is in line with findings from researchers who have observed a parietal/frontal network for viewer-centered coding.
This gives a glimpse at the way a language is interpreted in the brain by creating a model of what is understood by words.
Janzen, G., Haun, D., & Levinson, S. (2012). Tracking Down Abstract Linguistic Meaning: Neural Correlates of Spatial Frame of Reference Ambiguities in Language PLoS ONE, 7 (2) DOI: 10.1371/journal.pone.0030657