The effect of colour congruency on shape discriminations of novel objects.

Although visual object recognition is primarily shape driven, colour assists the recognition of some objects. It is unclear, however, just how colour information is coded with respect to shape in long-term memory and how the availability of colour in the visual image facilitates object recognition. We examined the role of colour in the recognition of novel, 3-D objects by manipulating the congruency of object colour across the study and test phases, using an old/new shape-identification task. In experiment 1, we found that participants were faster at correctly identifying old objects on the basis of shape information when these objects were presented in their original colour, rather than in a different colour. In experiments 2 and 3, we found that participants were faster at correctly identifying old objects on the basis of shape information when these objects were presented with their original part-colour conjunctions, rather than in different or in reversed part-colour conjunctions. In experiment 4, we found that participants were quite poor at the verbal recall of part-colour conjunctions for correctly identified old objects, presented as grey-scale images at test. In experiment 5, we found that participants were significantly slower at correctly identifying old objects when object colour was incongruent across study and test, than when background colour was incongruent across study and test. The results of these experiments suggest that both shape and colour information are stored as part of the long-term representation of these novel objects. Results are discussed in terms of how colour might be coded with respect to shape in stored object representations.

Impaired processing of prosodic and musical patterns after right hemisphere damage.

The distinction between the processing of musical information and segmental speech information (i.e., consonants and vowels) has been much explored. In contrast, the relationship between the processing of music and prosodic speech information (e.g., intonation) has been largely ignored. We report an assessment of prosodic perception for an amateur musician, KB, who became amusic following a right-hemisphere stroke. Relative to matched controls, KB's segmental speech perception was preserved. However, KB was unable to discriminate pitch or rhythm patterns in linguistic or musical stimuli. He was also impaired on prosodic perception tasks (e.g., discriminating statements from questions). Results are discussed in terms of common neural mechanisms that may underlie the processing of some aspects of both music and speech prosody.

A case of impaired auditory and visual speech prosody perception after right hemisphere damage.

It is well established that vision plays a role in segmental speech perception, but the role of vision in prosodic speech perception is less clear. We report on the difficulties in prosodic speech perception encountered by KB after a right hemisphere stroke. In addition to musical deficits, KB was suspected of having impaired auditory prosody perception. As expected, KB was impaired on two prosody perception tasks in an auditory-only condition. We also examined whether the addition of visual prosody cues would facilitate his performance on these tasks. Unexpectedly, KB was also impaired on both tasks under visual-only and audio-visual conditions. Thus, there was no evidence that KB could integrate auditory and visual prosody information or that he could use visual cues to compensate for his deficit in the auditory domain. In contrast, KB was able to identify segmental speech information using visual cues and to use these visual cues to improve his performance when auditory segmental cues were impoverished. KB was also able to integrate audio-visual segmental information in the McGurk effect. Thus, KB's visual deficit was specific to prosodic speech perception and, to our knowledge, this is the first reported case of such a deficit.