Solja K. Klargaard

On the Relation between Face and Object Recognition in Developmental Prosopagnosia: No Dissociation but a Systematic Association

There is an ongoing debate about whether face recognition and object recognition constitute separate domains. Clarification of this issue can have important theoretical implications as face recognition is often used as a prime example of domain-specificity in mind and brain. An important source of input to this debate comes from studies of individuals with developmental prosopagnosia, suggesting that face recognition can be selectively impaired. We put the selectivity hypothesis to test by assessing the performance of 10 individuals with developmental prosopagnosia on demanding tests of visual object processing involving both regular and degraded drawings. None of the individuals exhibited a clear dissociation between face and object recognition, and as a group they were significantly more affected by degradation of objects than control participants. Importantly, we also find positive correlations between the severity of the face recognition impairment and the degree of impaired performance with degraded objects. This suggests that the face and object deficits are systematically related rather than coincidental. We conclude that at present, there is no strong evidence in the literature on developmental prosopagnosia supporting domain-specific accounts of face recognition.

Are reading and face processing related? An investigation of reading in developmental prosopagnosia

Recent hypotheses suggest that learning to read influences the cognitive and cerebral organization of other perceptual skills, including face processing. Developmental prosopagnosia (DP) is a disorder of face recognition in the absence of acquired brain injury, and in the context of normal intelligence and general cognitive development. To shed light on the potential relationship between reading and face processing in this group (and in general), we investigated reading performance in 10 participants with DP and 20 matched controls. We find that the group of DPs perform strikingly similar to the control group on four sensitive reading tests measuring visual recognition and naming of single letters and words, word length effects, and text reading speed and comprehension. Thus, there is a clear dissociation between impaired face processing and preserved reading in this group, a finding that challenges the recently proposed hypothesis that reading acquisition and face processing abilities are intrinsically linked. Developmental prosopagnosics can learn to read as fluently as normal subjects, while they are seemingly unable to learn efficient strategies for recognizing faces.

Delayed processing of global shape information in developmental prosopagnosia

There is accumulating evidence suggesting that a central deficit in developmental prosopagnosia (DP), a disorder characterized by profound and lifelong difficulties with face recognition, concerns impaired holistic processing. Some of this evidence comes from studies using Navon’s paradigm where individuals with DP show a greater local or reduced global bias compared with controls. However, it has not been established what gives rise to this altered processing bias. Is it a reduced global precedence effect, changes in susceptibility to interference effects or both? By analyzing the performance of 10 individuals with DP in Navon’s paradigm we find evidence of a reduced global precedence effect: The DPs are slower than controls to process global but not local shape information. Importantly, and in contrast to previous studies, we demonstrate that the DPs perform normally in a comprehensive test of visual attention, showing normal: visual short-term memory capacity, speed of visual processing, efficiency of top-down selectivity, and allocation of attentional resources. Hence, we conclude that the reduced global precedence effect reflects a perceptual rather than an attentional deficit. We further show that this reduced global precedence effect correlates both with the DPs’ face recognition abilities, as well as their ability to recognize degraded (non-face) objects. We suggest that the DPs’ impaired performance in all three domains (Navon, face and object recognition) may be related to the same dysfunction; delayed derivation of global relative to local shape information.

Topographic processing in developmental prosopagnosia: Preserved perception but impaired memory of scenes

ABSTRACT Anecdotal evidence suggests a relation between impaired spatial (navigational) processing and developmental prosopagnosia. To address this formally, we tested two aspects of topographic processing – that is, perception and memory of mountain landscapes shown from different viewpoints. Participants included nine individuals with developmental prosopagnosia and 18 matched controls. The group with developmental prosopagnosia had no difficulty with topographic perception, but was reliably poorer in the retention of topographic information. Additional testing revealed that this did not reflect a general deficit in visual processing or visual short-term memory. Interestingly, a classical dissociation could be demonstrated between impaired face memory and preserved topographic memory in two developmental prosopagnosics. We conclude that impairments in topographic memory tend to co-occur with developmental prosopagnosia, although the underlying functions are likely to be independent.

Reading in developmental prosopagnosia: Evidence for a dissociation between word and face recognition

Objective: Recent models suggest that face and word recognition may rely on overlapping cognitive processes and neural regions. In support of this notion, face recognition deficits have been demonstrated in developmental dyslexia. Here we test whether the opposite association can also be found, that is, impaired reading in developmental prosopagnosia. Method: We tested 10 adults with developmental prosopagnosia and 20 matched controls. All participants completed the Cambridge Face Memory Test, the Cambridge Face Perception test and a Face recognition questionnaire used to quantify everyday face recognition experience. Reading was measured in four experimental tasks, testing different levels of letter, word, and text reading: (a) single word reading with words of varying length,(b) vocal response times in single letter and short word naming, (c) recognition of single letters and short words at brief exposure durations (targeting the word superiority effect), and d) text reading. Results: Participants with developmental prosopagnosia performed strikingly similar to controls across the four reading tasks. Formal analysis revealed a significant dissociation between word and face recognition, as the difference in performance with faces and words was significantly greater for participants with developmental prosopagnosia than for controls. Conclusions: Adult developmental prosopagnosics read as quickly and fluently as controls, while they are seemingly unable to learn efficient strategies for recognizing faces. We suggest that this is due to the differing demands that face and word recognition put on the perceptual system.

Are reading and face processing related?: A study of word processing in developmental prosopagnosia

Traditionally, perceptual processing of faces and words is considered highly specialized, strongly lateralized, and largely independent. This has, however, recently been challenged by studies showing that learning to read may affect the perceptual and neural processes involved in face recognition. In this light, investigating face processing in dyslexia, and reading in prosopagnosia becomes interesting: Do deficits in the two domains dissociate? Developmental prosopagnosia (DP) is a disorder of face processing in the absence of brain injury, and in the context of normal intelligence and general cognitive development. In three experiments, we investigated reading performance in a group of 11 participants with DP and matched controls: First, we examined if reading speed was affected by word length. Secondly, we compared RTs for single word and single letter stimuli. Third, we measured the word superiority effect in accuracy of word and letter report with brief exposure durations. These data were also analysed using methods based on a Theory of Visual Attention1, to extract estimates of perceptual processing speed for words and letters. We find that the group of DPs perform well within the normal range on all reading tests. They show normal reading RTs, and no abnormal word length effects. They also show an RT advantage for short words over single letters, as we have previously found in normal subjects.2 The DP group also show the typical word superiority effect, reflected in better overall accuracy, a lower perceptual threshold, and higher processing speed for words compared to letters. In sum, we find no evidence that reading skills are abnormal in developmental prosopagnosia, a finding that may challenge the recently proposed hypothesis that reading development and face processing abilities are intrinsically linked. References 1 Bundesen, C. (1990). Psych.Rev., 97, 523-547. 2 Starrfelt, R., et al. (2013). Front.Hum.Neurosci., 7, 519. Meeting abstract presented at VSS 2015.

Inversion effects for faces and objects in developmental prosopagnosia: A case series analysis

ABSTRACT The disproportionate face inversion effect (dFIE) concerns the finding that face recognition is more affected by inversion than recognition of non‐face objects; an effect assumed to reflect that face recognition relies on special operations. Support for this notion comes from studies showing that face processing in developmental prosopagnosia (DP) is less affected by inversion than it is in normal subjects, and that DPs may even display face inversion superiority effects, i.e. better processing of inverted compared to upright faces. To date, however, there are no reports of direct comparisons between inversion effects for faces and objects, investigating whether the altered inversion effect in DP is specific to faces. We examined this question by comparing inversion effects for faces and cars in two otherwise identical recognition tasks in a group of DPs (N=16) and a matched control group, using a case series design. Although both groups showed inversion effects for both faces and cars, only the control group exhibited a significant dFIE, i.e. a larger inversion effect for faces than cars. In comparison, the DPs were not significantly more affected by inversion than the control group when assessed with a face processing task that did not require recognition. Importantly, in both settings the DPs are better with upright than with inverted faces, and on the individual level no DP was found to perform significantly better with inverted than with upright faces. In fact, the DPs are impaired relative to the control group with both upright and inverted faces and to a less extent also with upright and inverted cars. These results yield no evidence of inversion superiority in DP but rather suggest that their face recognition problem is not limited to operations specialized for upright faces. HIGHLIGHTS16 adults with developmental prosopagnosia (DP) and 32 matched controls were tested.No disproportionate face inversion effect was found in DP on memory tasks.DPs showed similar face inversion effects as controls on a perception task.No DP exhibited a reliable paradoxical inversion effect.No association was found between inversion effects on memory and perception tasks.