Single words

2.5.1.1 Monomorphemic and morphologically complex substantives^

MC can read substantives very well. His reading is not affected by psycholinguistic variables such as imageability or frequency, nor by orthographic features such as word length (all controlled for in various tests, mainly from the PALPA Battery). Across many reading lists, comprising 731 nouns, verbs and adjectives, MC was 80.575% correct (589 words read correctly). His errors are visual or phonological

(producing a word which is orthographically or phonetically similar to the target) and very occasionally, semantic (i.e. related in meaning to the target). He is not affected by grammatical class membership; nouns, verbs and adjectives are all read equally well.

Most of M C ’s errors on morphologically complex substantives are errors of affixation. When reading morphologically complex words, he is very often unable to correctly read a derivational or inflectional affix, producing instead the appropriate stem either affixless or with a substituted affix. For instance, on a reading list controlled for morphological complexity (PALPA), MC read 34 out of 45 monomorphemic words correctly, and only 17 of the 45 morphologically complex words. His errors on the monomorphemic words were mixed, involving a few semantic errors (e.g. sand

‘rock’; wrist “> ‘elbow ’), a phonological error (fiend -> ‘fe e l’), two visual errors {mild ‘m ildew ’ and crux -> ‘cruise’), and three errors of affixation: murder ‘m urderer’, ride -> ‘riding’, and tank -> ‘tanker’. 22 of his errors on the morphologically complex words, however, involved the affixes; only 6 errors involved stems, and they were mainly visual errors (e.g. sold ‘so lid’, slimmer -> ‘sm ile’, crossed -> ‘across’).

A reading of regularly and irregularly inflected items from a PALPA reading list (PALPA 34) showed that MC treats regularly inflected words somewhat differently from those which are irregularly inflected. He read 4 out o f 15 regularly inflected words correctly, making 8 errors involving omission of the affix, and one involving substitution of -ing for -ed on a verb stem (the other two errors were visual and unrelated to the target). On the irregularly inflected words (all but one of which were verbs), however, he read 6 out o f 15 correctly but made only 4 omissions of inflection. Of his other errors on the irregularly inflected words, 2 were visual errors and 1 was unrelated to the target, whilst the remaining 2 were more complex morphological errors (sang -> ‘song’, a visual and / or derivational error; and froze ‘fr o ze n ’, an inflectional and / or derivational error). This pattern supports a view of regular inflections as relying solely on morphological processes; for MC, these are deficient, and he therefore makes errors involving omission or substitution of morphemes. Irregularly inflected words, however, are lexically represented. When MC is able to retrieve these and assign them an appropriate realisation at the morphological interface, all is well. But he still makes some errors, especially in the appropriate realisation of tense morphemes at the morphological

interface, even when an irregular (and hence lexicalised) realisation is available to him. This appears to be consistent with the hypothesis that his realisations of tense projections are limited (sections 2.2.2 above and 2.11 below).

MC does make other, non-morphological, kinds of errors on reading of single substantives, as the assessments from PALPA showed. But the proportions o f such errors are very small compared to his morphological errors. Because it can be very difficult to determine whether an aphasie patient is really making errors of affixation, rather than carrying out whole word substitutions which are phonologically, visually and / or semantically related to the target (which affixed words tend to be - see discussion in

1.3.1 above, and also Badecker and Caramazza 1998), MC was given another list of monomorphemic and morphologically complex substantives to read (the whole list is given in Appendix IV). This list contained inflected and pseudo-inflected words - for example, babies and rabies’, walking and awning', shouted and wicked (based on an idea from Badecker and Caramazza 1987). The list consisted of 22 pairs of inflected words with monomorphemic controls. MC read 21/22 of the monomorphemic controls correctly, making one error which may be visual or morphological in nature {dozen

‘dozing’). On the inflected words, by contrast, he read only 11 correctly (and 8 of these were -ing participles, which is M C’s preferred form for verbs). His errors were all morphological: on 5 items the affix was omitted, on 5 verbs the affix was changed to - ing, and one verb was altered from past tense {-ed) to present tense / 3"^^ person (-j).

A third list was presented to MC to ascertain whether his underlying deficit on single substantives is really morphological in nature. 28 pairs of homophones were generated, such that one homophone was inflected and the other was monomorphemic - for example, bored and board', days and daze', knows and nose. Such a list is designed to rule out the possibility that phonological factors are determining responses, since the members o f the homophone pairs are phonologically related but morphologically dissimilar. If MC treats the two sets of words in different ways, then it is more evidence to support the characterisation of reading deficits on single substantives as underlyingly morphological in nature.

As predicted, MC made very few errors when reading the monomorphemic half of the reading list, reading 24 out of 28 correctly. His errors were visual {paste ^ ‘pasta ’ and daze ‘d o ze’) and morphological {mast -> ‘m aster’ and choose ‘choice’). On

the morphologically complex half of the reading list, however, MC made 25 morphological errors of substitution or omission of affixes. All the stems were produced correctly. Most of the errors (18) involved substitution of the -ing affix for -ed or -s on verbs; there were 4 instances of affix omission, and three more complex errors: ducked -> ‘duckling’, days ‘daylight’ and massed ‘am ass’.

In other words, MC presents with a morphological deficit in his reading of single substantives, and careful testing has shown that he is not consistently affected by any non-morphological variable.

2.5.1.2 Function words'*

M C ’s reading of function words is in direct contrast to his reading of substantives. He performs extremely poorly, being unable to produce accurate responses to any function word. His responses do show that he has recognised some categorial information associated with function words, because his responses to these items only consist in the quasi-random production of various other function words. Some examples are given in table one below (from Froud, to appear), which also illustrates the contrast between M C ’s reading of functors and substantives.

M C ’s performance on the reading of function words is much worse than that of comparable patients in the aphasiology literature, and I draw some comparisons in section 2.10.1 below. But it is clear, even before such comparisons are made, that M C ’s function word reading deficit is extraordinarily pure and robust. From the corpus of M C ’s reading responses, a total of 651 examples of function words were identified. Out of these, he made 519 (79.724%) function word substitution errors, getting only 76 correct (11.674%) and either failing to respond or producing a substantive (which was usually unrelated to the target, but sometimes bore it a visual, semantic or morphological resemblance) in the other cases.