Kavitha Srinivas

Perceptual specificity in nonverbal priming.

Five experiments were conducted to examine whether varying certain perceptual attributes of study and test items influences priming on pictorial tasks. Priming was found to be specific to the form of studied items; substantial priming occurred from studying pictures, whereas little or no priming occured from studying the pictures names (read or generated). Priming was specific to the exact contour presented at study. Studying the same fragment that was presented at test resulted in greater priming than did studying an intact image or a different fragment of the object. Priming was also specific to the viewing angle of studied objects. Same study-test views showed the greatest priming, whereas priming across different views was greater when subjects studied an unusual view of the object and were tested on a canonical view than when the reverse was true

Do vision and haptics share common representations? Implicit and explicit memory within and between modalities.

Previous assessments of verbal cross-modal priming have typically been conducted with the visual and auditory modalities. Within-modal priming is always found to be substantially larger than cross-modal priming, a finding that could reflect modality modularity, or alternatively, differences between the coding of visual and auditory verbal information (i.e., geometric vs. phonological). The present experiments assessed implicit and explicit memory within and between vision and haptics, where verbal information could be coded in geometric terms. Because haptic perception of words is sequential or letter-by-letter, experiments were also conducted to isolate the effects of simultaneous versus sequential processing from the manipulation of modality. Together, the results reveal no effects of modality change on implicit or explicit tests. The authors discuss representational similarities between vision and haptics as well as image mediation as possible explanations for the results.

Transfer between vision and haptics: Memory for 2-D patterns and 3-D objects

Explicit memory tests such as recognition typically access semantic, modality-independent representations, while perceptual implicit memory tests typically access presemantic, modality-specific representations. By demonstrating comparable cross- and within-modal priming using vision and haptics with verbal materials (Easton, Srinivas, & Greene, 1997), we recently questioned whether the representations underlying perceptual implicit tests were modality specific. Unlike vision and audition, with vision and haptics verbal information can be presented in geometric terms to both modalities. The present experiments extend this line of research by assessing implicit and explicit memory within and between vision and haptics in the nonverbal domain, using both 2-D patterns and 3-D objects. Implicit test results revealed robust cross-modal priming for both 2-D patterns and 3-D objects, indicating that vision and haptics shared abstract representations of object shape and structure. Explicit test results for 3-D objects revealed modality specificity, indicating that the recognition system keeps track of the modality through which an object is experienced.

Obligatory Processing of the Literal Meaning of Ironic Utterances: Further Evidence

We tested the hypotheses that the literal meaning of an ironic utterance is activated during comprehension and (a) slows the processing of the key ironic portion of the utterance (literal activation hypothesis) and (b) slows the processing of the literal portion of the utterance that follows (the spillover hypothesis). Forty-eight stories, each ending in an ironic comment, were constructed. Half of the ironic comments were ironic criticism (positive literal meaning, negative ironic meaning); half were ironic praise (negative literal meaning, positive ironic meaning). Final utterances were divided into 3 phrases: Phrase 1 gave no indication of irony, Phrase 2 contained the key word that made the utterance ironic, and Phrase 3 gave no indication of irony. Each story was then altered by 1 phrase so that the final comment became literal. One version of each of the stories was presented to each of 48 college undergraduates. Stories were presented 1 sentence at a time, but the final utterances were presented in 3 consecutive phrases. Participants pressed the space bar as soon as they understood the sentence or phrase presented. For ironic criticism, participants took longer to process the key phrases in an irony- than a literal-biasing context, but they took longer to process the final (literal) phrase following irony only when the analysis was performed for item rather than participant variability. For ironic praise, participants again took longer to process the key phrases in an irony- than a literal-biasing context, but this difference did not reach significance, and they did not take any longer to process the final phrase following irony. Thus, results support the literal activation hypothesis in the case of ironic criticism but not ironic praise and provide no clear support for the spillover hypothesis.

REPRESENTATION OF ROTATED OBJECTS IN EXPLICIT AND IMPLICIT MEMORY

The effects of rotating familiar and novel objects in depth between study and test were explored on short-term recognition, long-term recognition, and priming tasks. Short-term recognition memory was not affected by rotation in depth when the study and test views shared the same visible parts. However, long-term recognition was sensitive to rotation, even when all the parts were visible in both views. Priming was also affected by rotation, but only when study and test views did not share the same parts, or when test views were generated from rotations greater than 67 degrees. Together, the results suggest that long-term recognition memory is mediated by representations that specify viewpoint in depth precisely, whereas priming is mediated by representations that are more broadly tuned with respect to orientation. Furthermore, the insensitivity of the short-term recognition memory task to rotation suggests the possibility that viewpoint-invariant descriptions are generated from multiple successive views.

Size and reflection effects in priming: A test of transfer-appropriate processing

Prior research has suggested that priming on perceptual implicit tests is insensitive to changes in stimulus size and reflection. The present experiments were performed to investigate whether size and reflection effects can be obtained in priming under conditions that encourage the processing of this information at study and at test, as predicted by transfer-appropriate processing. The results indicate that priming was affected by a change in the physical size of an object when study and test tasks required a judgment about the real size of pictorial objects (e.g., deciding whether a zebra presented small or large on the screen was larger or smaller than a typical chair), and when the test task required the identification of fragmented pictures. However, a change in left-right orientation had no effect on priming when study and test tasks required a judgment about the left-right orientation of familiar objects, or when the test task involved the identification of fragmented pictures. This difference between size and reflection effects is discussed in terms of the differential importance of size and reflection information in shape identification.

The effects of attention on perceptual implicit memory

Reports on the effects of dividing attention at study on subsequent perceptual priming suggest that perceptual priming is generally unaffected by attentional manipulations as long as word identity is processed. We tested this hypothesis in three experiments by using the implicit word fragment completion and word stem completion tasks. Division of attention was instantiated with the Stroop task in order to ensure the processing of word identity even when the participant’s attention was directed to a stimulus attribute other than the word itself. Under these conditions, we found that even though perceptual priming was significant, it was significantlyreduced in magnitude. A stem cued recall test in Experiment 2 confirmed a more deleterious effect of divided attention on explicit memory. Taken together, our findings delineate the relative contributions of perceptual analysis and attentional processes in mediating perceptual priming on two ubiquitously used tasks of word fragment completion and word stem completion.

Intact perceptual priming in a patient with damage to the anterior inferior temporal lobes

We conducted three experiments to examine whether the anterior portion of the inferior temporal (IT) lobe is involved in the processing of visual objects in humans. In monkeys, damage to this region results in severe deficits in perception and in memory for visual objects. Our study was designed to examine both these processes in a patient (DM) with bilateral damage to the anterior portion of the inferior temporal lobe. Neuropsychological examination revealed a significant semantic impairment and a mild deficit in the discrimination of familiar objects from nonobjects. Despite these difficulties, the results of several studies indicated that DM was able to form and retain descriptions of the structure of objects. Specifically, DM showed normal perceptual priming for familiar and novel objects on implicit memory tests, even when the objects were transformed in size and left-right orientation. These results suggest that the anterior IT is notinvolved in (1) the storage of pre-existing structural descriptions of known objects, (2) the ability to create new structural descriptions for novel objects, and (3) the ability to compute descriptions that are invariant with respect to changes in size and reflection. Instead, the anterior IT appears to provide the interface between structural descriptions of objects and their meanings.

A transfer-appropriate processing account of context effects in word-fragment completion

The claim that priming on implicit memory tasks such as word-fragment completion is sensitive to context effects was tested by using homographs (e.g., board) to manipulate context. On the basis of previous findings, it was assumed that presentation of only the perceptual cue at test (._oa_d) should activate the dominant meaning, thereby creating the same context for homographs encoded for their dominant encoding and a different context for homographs encoded for their nondominant meaning. As expected, little or no effect of varying context was observed on a perceptual implicit task (Experiments 1-2B). When explicit retrieval instructions were given in Experiment 3, same-context encoding led to greater recall of homographs from word-fragment cues relative to different-context encoding. These results are consistent with the predictions of the transfer-appropriate-processing view because little advantage for the same-context condition was obtained in implicit tests in the absence of conceptual cues.

CONTRAST AND ILLUMINATION EFFECTS ON EXPLICIT AND IMPLICIT MEASURES OF MEMORY

The present study examined the effect of changing the contrast polarity and illumination of objects on explicit (episodic recognition) and implicit (fragment naming or object-nonobject decision) memory tasks. Changes in contrast polarity of line drawings of objects did not affect priming on fragment naming or on object-nonobject decision tasks but adversely affected recognition judgments. Similarly, changes in illumination did not affect priming on the object-nonobject decision task but adversely affected recognition memory. Together, the results suggest that implicit measures tap abstract descriptions of object structure useful for the purposes of object identification, whereas recognition memory taps descriptions that integrate shape information with lower level perceptual information. It is argued that lower level perceptual information influences episodic recognition because it provides a cue to the spatiotemporal context within which the prior encounter with the object occurred.