Age effect in generating mental images of buildings but not common objects.

Imagining a familiar environment is different from imagining an environmental map and clinical evidence demonstrated the existence of double dissociations in brain-damaged patients due to the contents of mental images. Here, we assessed a large sample of young and old participants by considering their ability to generate different kinds of mental images, namely, buildings or common objects. As buildings are environmental stimuli that have an important role in human navigation, we expected that elderly participants would have greater difficulty in generating images of buildings than common objects. We found that young and older participants differed in generating both buildings and common objects. For young participants there were no differences between buildings and common objects, but older participants found easier to generate common objects than buildings. Buildings are a special type of visual stimuli because in urban environments they are commonly used as landmarks for navigational purposes. Considering that topographical orientation is one of the abilities mostly affected in normal and pathological aging, the present data throw some light on the impaired processes underlying human navigation.

The trauma symptom inventory: Italian validation of an instrument for the assessment of post-traumatic symptoms.

AIM: The trauma symptom inventory (TSI; Briere, 1995) is a useful instrument for the assessment of post-traumatic and common trauma-related mental health symptoms. The purpose of the study was to validate the Italian version of the original TSI. METHODS: Participants from non-clinical (n = 285), clinical (n = 110) and post-traumatic (n = 30) samples completed the TSI as part of a battery that included self-report measures of trauma exposure [MMPI-2 PK scale and Impact of Event Scale-Revised (IES-R)] and of psychological symptoms [brief symptom inventory (BSI) and symptom questionnaire (SQ)]. TSI validity scales were compared with MMPI-2 validity scales in order to assess convergent validity. RESULTS: The TSI Italian version showed adequate internal consistency reliability and a good convergent validity. Discriminant function analysis indicates a classification accuracy of TSI scales of 90% for true-positive and 91.4% for true-negative post-traumatic stress disorder (PTSD) cases. A revised three-factor structural model, which demonstrated an adequate and the best fit for the data, was proposed. CONCLUSIONS: The study extended the generalization and validity of TSI and provided some suggestions for eventually revisiting factorial structure of the questionnaire.

Vividness in judgements of guilt.

This study investigated the vividness variable in legal decision-making. It was hypothesised that different verdicts regarding the same legal case can be obtained by simply varying the vividness of phrases, without changing any probative element. 53 participants read Original (26) or Vivid (27) versions of testimonies to a homicide case, then made a decision as to the defendant's guilt. Results support the hypothesis: participants' judgements significantly differ between the two conditions; that is, participants who read the Original version consider the homicide as unintentional while participants who read the Vivid one are not able to choose between intentional or unintentional homicide. Therefore we can infer that vividness influenced the process by which guilt is attributed.

Moving around objects and recognizing them.

This research concerned the use of mental rotation in recognizing rotated objects. Instead of the classic Shepard's paradigm in which subjects were still while observing rotated objects, here subjects had to move (or imagine moving) around stationary three-dimensional objects put in the middle of the trajectory. Thus, depending on the viewing positions, such objects were seen under six different perspectives (from 30 degrees to 180 degrees). The latter task has been thought to be closer to everyday life in which we obtain information regarding objects from their spatial properties. The results do not follow the classic rules of mental rotation of an object predicting a linear increase of the time needed to recognize distorted objects as a function of their angular displacement. They also differ from data in the literature about spatial imagery showing that access to spatial information is facilitated more when people actually move through a path than when they imagine moving. A probable explanation of this difference from the literature is discussed in relation to the particular involvement of the body in the experimental task.

Metric aspects of mental images.

This research concerns the representation of size and shape in long-term memory at different levels of abstraction. Some authors suggested a distinction between surface characteristics, including size, depending on an observer's point of view (viewer-centered), and abstract characteristic based only on an object's shape (object-centered). These studies raise the question of whether size-information is stored in long-term memory. This question may be dealt with by considering the topic of cognitive costs; since abstract representation needs more processing, more time is required to store fewer abstract representations than many viewer-level representations. Two hypotheses were put forward: information about size is preserved when an intermediate time is allowed to process visual stimuli, whereas it is discarded when a longer time is available; subjects who have longer time focus on shape, while subjects who have less time do not. Subjects were assigned to two groups differing in the time allowed to learn visual images. Both groups had to recognize previously learned visual mental images. These images were built up by a subtraction task. The testing stimuli were identical to learned ones, of a different size, or of a different shape. Analysis showed that information about size is not held in long-term memory. As regards shape, results were controversial.

Differences in vividness ratings of perceived and imagined patterns.

The present research focuses on the different subjective experiences evoked by perceived and imagined matrices of letters of the alphabet. In three experiments adult subjects were asked to rate the vividness of a letter included in a matrix of letters which varied due to manipulations in colour, rotation and movement. Subjects were asked to observe (perceptual modality), draw and observe (drawing modality), retrieve (memory modality) or imagine (imagery modality) the matrices. For some manipulations of the critical letter (in particular, 45 degrees inclination and high contrast colour), the perceptual modality produced comparatively higher vividness ratings than the other two modalities. The perceptual effect of inclination was also duplicated with the memory modality group. It is argued that different visual processes, either immediate and pre-attentive, or sequential and attentive, may be operating under voluntary control. Although visual imagery varies in some ways from immediate visual perception, the similarities found, between the drawing and imagery modalities, on the one hand, and the perceptual and memory modalities, on the other hand, suggest that they share some common underlying processes.