Truth conditions & Entailment

4.3 Verification study (Tiemann, 2011, Experiment 1)

This study focuses exclusively on presupposition triggers, with the goal of testing whether the pragmatic processing that arises with such words starts mid-sentence before the full syntactic structure of the sentence is even computed. The target sentence was always the same and always contained a presupposition trigger. What varied was the preceding context: a 'verify' sentence or a 'falsify' sentence, which set up as either true or false the proposition presupposed by the target sentence.

Context sentence variants:

Context sentence: verify
Susanne hat dieses Jahr bereits rote Handschuhe gekauft.
Susanne had this year already red gloves bought.
Susanne had already bought red gloves this year.'

Context sentence: falsify
Susanne hat bisher nie rote Handschuhe gekauft.
Susanne had until now never red gloves bought.
Susanne had never bought red gloves until now.'

Target sentence (always the same):

Target sentence: trigger
Heute hat Susanne wieder rote Handschuhe gekauft und sie gleich angezogen.
Today has Susanne again red gloves bought and then immediately put them on.
'Today, Susanne bought red gloves again and put them on right away.'

How many conditions? [click to reveal]
There are two conditions. The verify-context condition is predicted to yield easier processing than the falsify-context condition when participants encounter the target sentence. If so, the target sentence should yield higher ratings and faster reading times in the verify condition than the falsify condition.

In the example above, it's wieder ('again').

What's the critical word? [click]
In the example, it's gekauft ('bought').
- Where are faster reading times predicted (on the trigger or on the critical word)? [click]
  At the critical word, when comprehenders must check if the context contains the presupposed content.

Figure 2 below shows the results from the Verification rating study. As predicted, the verifying context yielded higher ratings than the falsifying context.

Figure 2: Verification study, Tiemann et al. 2011

The reading time results showed a similar pattern whereby the critical word ('bought') was read faster in the verifying condition than the falsifying condition. These results can be taken as evidence that comprehenders start pragmatic processing early, well before the sentence is complete. There were no reading-time differences by condition at the trigger word.

Would you expect different reading times by condition at the trigger word? [click]
As you can see in the example stimuli above, the trigger word 'again' comes before the reader knows what event is under discussion (i.e., what event happened 'again'). At that point, the reader can't know whether the subsequent material in the sentence will describe something that had happened before or not.

KEY POINT: Offline acceptability ratings and online reading times both point to comprehension difficulty in passages in which a presupposition is not supported by the context.

To go on to section 4.4 "Accommodation study", click here.