Degrees of processing and memory load

J Bohan and A J Sanford
University of Glasgow

A Newlands
University of Strathclyde

There is substantial but scattered data suggesting that the meanings of words may not be fully utilised in all cases, but that shallower processing might take place. Possible factors controlling depth of processing might include focussing and processing load, both due to sentence structure.

The depth of semantic processing of a word may be indexed by the likelihood of detecting that word when it appears as an anomaly. In experiment 1, we compared the detection of an anomaly under high and low- memory load conditions, using parenthetical material to manipulate load, as in

There is increasing concern from nursing unions that their members are underpaid. UNISON has threatened strike action .... ......However, critics argue that strike action could seriously affect people in their care.

Would you support a national strike, possibly quite lengthy and disruptive, that demanded a reasonable pay settlement for all patients in NHS hospitals? (HIGH LOAD, with parenthetical)

Would you support a national strike that demanded a reasonable pay-settlement for all patients, even though it may be quite lengthy and disruptive to NHS hospitals? (LOW LOAD, no parenthetical)

Here the anomaly is that it is not the patients who require the pay-settlement. In a question-answering task using 24 such materials, 97% of errors were recognised in the low load, compared to only 52% in the high-load condition. This shows shallower semantic processing in the high-load case.

Using a text change-blindness procedure, in which there are two exposures of a passage in quick succession, the second of which might contain a changed word, load effects were also observed. We compared detections of changes for object-relative and subjective relative sentences on the main verb, as in:

(1) The reporter who attacked the senator ignored the president.
(2) The reporter who the senator attacked ignored the president.

(2) is rated as more difficult to process than (1) (Gibson, 1998), and if ignored is changed to snubbed, it is noticed less in (2) than in 1.

A short series of similar studies will be presented in support of the claim that in high-load sentence environments, semantic processing may become shallow.