Implied velocity and acceleration induce transformations of visual memory

In this study, the phenomenon of representational momentum (Freyd & Finke, 1984) is investigated in cases where visual memories are distorted by implied motions of the elements of a pattern. Our theory predicts that these memory distortions should be sensitive not only to the direction of the implied motions but also to changes in the implied velocity. Subjects observed a sequence of dot-pattern displays that implied that the dots were moving at either a constant velocity or constant acceleration, but in separate directions. Discrimination functions for recognizing the final pattern in the sequence revealed that subjects' memories had shifted forward, corresponding to small continuations of the implied motions. The induced memory shifts increased in size as the implied velocity and acceleration of the dots increased, but were eliminated when the display sequence implied a deceleration of the dots to a final velocity of zero. These findings suggest that mentally extrapolated motion may have some of the same inertial properties as actual physical motion.     

Transformations of visual memory induced by implied motions of pattern elements

Four experiments measured distortions in short-term visual memory induced by displays depicting independent translations of the elements of a pattern. In each experiment, observers saw a sequence of 4 dot patterns and were instructed to remember the third pattern and to compare it with the fourth. The first three patterns depicted translations of the dots in consistent, but separate directions. Error rates and reaction times for rejecting the fourth pattern as different from the third were substantially higher when the dots in that pattern were displaced slightly forward, in the same directions as the implied motions, compared with when the dots were displaced in the opposite, backward directions. These effects showed little variation across interstimulus intervals ranging from 250 to 2,000 ms, and did not depend on whether the displays gave rise to visual apparent motion. However, they were eliminated when the dots in the fourth pattern were displaced by larger amounts in each direction, corresponding to the dot positions in the next and previous patterns in the same inducing sequence. These findings extend our initial report of the phenomenon of "representational momentum" (Freyd & Finke, 1984a), and help to rule out alternatives to the proposal that visual memories tend to undergo, at least to some extent, the transformations implied by a prior sequence of observed events.     

The relationship between mental rotation and representational momentum

Two experiments explored a possible relationship between mental rotation and representational momentum, a task in which participants were asked to remember an object's position following a sequence of images implying motion. Typically, participants misremember the position as distorted forward along the implied trajectory. If representational momentum relies on mental imagery, the magnitude of memory distortion in a representational momentum task should be positively correlated with the rate of mental rotation. As predicted, faster mental rotation rates and larger memory distortions for object position were observed for rotational axes aligned with the viewers' coordinate system. In addition, participants with slower mental rotation rates produced smaller memory distortions in the implied-event task.     

Parallels between remembering and predicting an object's location

Three experiments explore effects of rotational axis and velocity on observers' predictions regarding an object's future position, and begin to explore connections between this extrapolation task and representational momentum (RM). In general, observers accept as "correct" positions that are behind the correct extrapolated location, as shown in previous work (Cooper & Munger, 1993; Finke & Shyi, 1998). These prediction distortions are in the opposite direction of typical RM memory distortions, suggesting that these tasks are unrelated. However, new effects of axis for the extrapolation task are reported which parallel axis effects previously observed for RM and mental rotation tasks. Specifically, participants make larger negative distortion errors for axes of rotation that are not coincident with the viewer's coordinate system, as if these paths of rotation are harder to extrapolate. Effects of velocity and axis are examined for RM and extrapolation tasks, and the overall pattern of distortions supports a link. In particular, participants who misremember the location of an object as further along the implied path of motion also accept as "correct" positions relatively further along the extrapolated path of motion, suggesting that these apparently opposite types of errors are indeed related.     

Representational momentum in memory for pitch

When a visual pattern is displayed at successively different orientations such that a rotation or translation is implied, an observer's memory for the final position is displaced forward. This phenomenon of representational momentum shares some similarities with physical momentum. For instance, the amount of memory shift is proportional to the implied velocity of the inducing display; representational momentum is specifically proportional to the final, not the average, velocity; representational momentum follows a continuous stopping function for the first 250 ms or so of the retention interval. In a previous paper (Kelly & Freyd, 1987) we demonstrated a forward memory asymmetry using implied changes in pitch, for subjects without formal musical training. In the current paper we replicate our earlier finding and show that the forward memory asymmetry occurs for subjects with formal musical training as well (Experiment 1). We then show the structural similarity between representational momentum in memory for pitch with previous reports of parametric effects using visual stimuli. We report a velocity effect for auditory momentum (Experiment 2), we demonstrate specifically that the velocity effect depends on the implied acceleration (Experiment 3), and we show that the stopping function for auditory momentum is qualitatively the same as that for visual momentum (Experiment 4). We consider the implications of these results for theories of mental representation.     

Representational momentum for rotations in depth: effects of shadings and axis

Representational momentum is a positive memory distortion for an object's final position following the presentation of an implied event (J.J. Freyd, 1987). Positive memory distortions occur when observers accept test positions beyond the final presented position, or forward along the implied trajectory, as the same more readily than positions behind the final position. Four experiments explored implied events depicting rotations about various depth axes in shaded and silhouette conditions. Positive memory distortions were observed for all depth rotations under certain shading conditions, with some differences in the size of the distortion between axes. No directional effects (e.g., right vs. left) were observed. The overall positive memory distortions observed for depth rotations contrasted with the negative distortions previously observed for translation motion in depth (T.L. Hubbard, 1995 ).     

Environmental invariants in the representation of motion: Implied dynamics and representational momentum,gravity, friction,and centripetal force

Memory for the final position of a moving target is often shifted or displaced from the true final position of that target. Early studies of this memory shift focused on parallels between the momentum of the target and the momentum of the representation of the target and called this displacementrepresentational momentum, but many factors other than momentum contribute to the memory shift. A consideration of the empirical literature on representational momentum and related types of displacement suggests there are at least four different types of factors influencing the direction and magnitude of such memory shifts: stimulus characteristics (e.g., target direction, target velocity), implied dynamics and environmental invariants (e.g., implied momentum, gravity, friction, centripetal force), memory averaging of target and nontarget context (e.g., biases toward previous target locations or nontarget context), and observers’ expectations (both tacit and conscious) regarding future target motion and target/context interactions. Several theories purporting to account for representational momentum and related types of displacement are also considered.     

Representational momentum and event course anticipation in the perception of implied periodical motions.

After viewing an object in an implied rotation, subjects' short-term visual memory for the object's position is distorted in the direction of rotation. Previous accounts of this representational momentum effect have emphasized the analogy to physical momentum. This study provides a more general perspective: Position memory is influenced by anticipatory processes related to the future event course. In Experiment 1, subjects are presented with an implied periodical event in which a rectangle rotates back and forth. When a direction change in the implied rotation can be anticipated, memory distortion size drops back to zero. Experiment 2 rejects an alternative explanation for the findings of Experiment 1 in terms of enhanced position memory caused by repeated presentations of the memory pattern orientation within the same trial. In Experiment 3, the periods of the implied event are marked by changes in velocity rather than direction. The anticipation of a sudden velocity increase leads to a larger memory shift. We conclude that the perceptual system anticipates the event course on the basis of a representation of the higher order event structure rather than the local motion characteristics.     

You heard it here first: Readers mentally simulate described sounds

The present experiments examined whether readers spontaneously simulate implied auditory elements of sentences. Participants read sentences that implicitly conveyed details that could provoke auditory imagery (e.g., The engine clattered as the truck driver warmed up his rig.), and then performed an unrelated sound categorization task during which they classified sounds as real (occurring in the world) or fake (computer generated). In Experiment 1 these two tasks were performed in sequence; in Experiment 2 they were separated into three experimental blocks to rule out the possibility that readers strategically formed auditory imagery as a result of task demands. In both studies, readers were faster to correctly categorize sounds as ‘real’ when the sounds had been implied by a preceding sentence. These results suggest that readers mentally simulate the implied auditory characteristics of sentences, even in the absence of tasks that promote mental simulation. Mentally simulating described events is not limited to visual and action-based modalities, further demonstrating the multimodal nature of the perceptual symbols spontaneously activated during reading.     

Representational momentum,spatial layout,and viewpoint dependency

Completing a representational momentum (RM) task, participants viewed one of three camera motions through a scene and indicated whether test probes were in the same position as they were in the final view of the animation. All camera motions led to RM anticipations in the direction of motion, with larger distortions resulting from rotations than a compound motion of a rotation and a translation. A surprise test of spatial layout, using an aerial map, revealed that the correct map was identified only following aerial views during the RM task. When the RM task displayed field views, including repeated views of multiple object groups, participants were unable to identify the overall spatial layout of the scene. These results suggest that the object–location binding thought to support certain change detection and visual search tasks might be viewpoint dependent.     

Attention maintains mental extrapolation of target position: irrelevant distractors eliminate forward displacement after implied motion

Observers' judgments of the final position of a moving target are typically shifted in the direction of implied motion ("representational momentum"). The role of attention is unclear: visual attention may be necessary to maintain or halt target displacement. When attention was captured by irrelevant distractors presented during the retention interval, forward displacement after implied target motion disappeared, suggesting that attention may be necessary to maintain mental extrapolation of target motion. In a further corroborative experiment, the deployment of attention was measured after a sequence of implied motion, and faster responses were observed to stimuli appearing in the direction of motion. Thus, attention may guide the mental extrapolation of target motion. Additionally, eye movements were measured during stimulus presentation and retention interval. The results showed that forward displacement with implied motion does not depend on eye movements. Differences between implied and smooth motion are discussed with respect to recent neurophysiological findings.     

Higher order pattern structure influences auditory representational momentum

Representational momentum refers to the phenomenon that observers tend to incorrectly remember an event undergoing real or implied motion as shifted beyond its actual final position. This has been demonstrated in both visual and auditory domains. In 5 pitch discrimination experiments, listeners heard tone sequences that implied either linear, periodic, or null motions in pitch space. Their task was to judge whether the pitch of a probe tone following each sequence was the same or different from the final sequence tone. Results suggested that listeners made errors consistent with extrapolation of coherent pitch patterns (linear, periodic) but not with incoherent (null) ones. Hypotheses associated with internalized physical principles and pattern-based expectations are discussed.     

Contrasting Cortical Activity Associated with Category Memory and Recognition Memory

We collected functional neuroimaging data while volunteers performed similar categorization and recognition memory tasks. In the categorization task, volunteers first studied a series of 40 dot patterns that were distortions of a nonstudied prototype dot pattern. After a delay, while fMRI data were collected, they categorized 72 novel dot patterns according to whether or not they belonged to the previously studied category. In the recognition task, volunteers first studied five dot patterns eight times each. After a delay, while fMRI data were collected, they judged whether each of 72 dot patterns had been studied earlier. We found strikingly different patterns of brain activity in visual processing areas for the two tasks. During the categorization task, the familiar stimuli were associated with decreased activity in posterior occipital cortex, whereas during the recognition task, the familiar stimuli were associated with increased activity in this area. The findings indicate that these two types of memory have contrasting effects on early visual processing and reinforce the view that declarative and nondeclarative memory operate independently.     

Simultaneous vs sequential discriminations of Markov-generated stimuli

This experiment required Ss to make same-different classifications of Markov-generated histoforms that were distortions of three different prototypes. Task memory requirements were varied by presenting stimuli either simultaneously or sequentially for comparison, and the effects of shifts in memory requirements were also assessed. Classification performance in all cases was found to be superior under the simultaneous condition. Postshift performance was strictly a function of the mode of stimulus presentation following the shift, rather than the memory requirements present in the initial trials. These results, coupled with the observed relationships between performance and a measure of individual stimulus variability under the two memory conditions, strongly suggest that prototype encoding has limited relevance to performance in the same-different classification task used here.     

Mental extrapolation and cognitive penetrability: reply to Ranney and proposals for evaluative criteria

We propose three criteria for establishing that mentally extrapolated motions are impenetrable with respect to one's knowledge, beliefs, or expectations about the nature of corresponding physical motions, and we review recent findings on mental extrapolation and representational momentum that appear to meet these criteria. We also respond to some arguments recently proposed by Ranney (1989) and Hubbard and Bharucha (1988) that representational momentum is cognitively penetrable. We conclude that mental extrapolations are governed to at least some extent by the inherent properties of the underlying internal mechanisms.     

Musical Memory in Alzheimer Disease

ABSTRACT

This study examines musical memory in 12 patients with moderate or severe AD and 12 healthy, older adult controls. Participants were asked to distinguish familiar from novel tunes, to identify distortions in melodies, and to sing familiar tunes. Comparison of the AD and control groups showed significant impairment of the AD participants. However, a more complex picture emerged as we compared each individual case to the control group. Five of the AD group performed within the control group range on most tasks. An additional four participants showed partial sparing in that they performed below the range of control participants, but their scores were above the level of chance. The final three participants showed near complete loss of musical memory, as their performance was consistently at or near the level of chance. These results are discussed in terms of the literature on the heterogeneity of cognitive presentation in AD.     

Dissociation of data-based and expectancy-based memory following hippocampal lesions in rats

Sham-operated and nonoperated animals or animals with hippocampal lesions were presented with sets of trials to test both expectancy-based and data-based memory within the same task. During the study phase of each trial the animals were presented with a constant sequence of five arms on an eight-arm radial maze followed by a test phase in which a recognition test requiring a win-stay rule was used. Expectancy-based memory was measured during the study phase of the trials as a pattern of correct or incorrect orienting responses in anticipation of the ensuing doors in the constant sequence. Both groups of animals acquired correct orienting responses at the same rate, emitted the same pattern of correct orienting responses, and made the same number and pattern of intralist and extralist intrusion errors. Data-based memory was measured during the test phase of the trial as correct recognition test performance. During the test phase the animals with hippocampal lesions were impaired relative to controls on both immediate and 24-h recognition tests. These results suggest that the hippocampus might mediate only data-based, but not expectancy-based, memory and imply a possible dissociation between expectancy-based and data-based memory systems.     

The locus of “memory displacement” is at least partially perceptual: Effects of velocity, expectation, friction, memory averaging, and weight

When observers are asked to localize the final position of a moving target, the judged position is usually displaced from the actual position. It has been suggested that mental processes derived from a number of invariant and noninvariant principles produce the mislocalization in memory. In this study, the effects of velocity, expectation, friction, memory averaging, and weight were reconsidered, and evidence was accumulated that supports the alternative view that the distortions arise to a large degree at a perceptual level. Effects of velocity and expectation were present when observers still perceived a persisting image of the target. It is suggested that the active reorienting of the perceptual organs explains the distortions. Furthermoremore, distortions of the perceived center of a visible stimulus may explain effects that have previously been attributed to memory averaging and mental analogues of weight. Thus, the locus of memory displacement is at least partially perceptual.     

The locus of "memory displacement" is at least partially perceptual: effects of velocity,expectation, friction,memory averaging,and weight

When observers are asked to localize the final position of a moving target, the judged position is usually displaced from the actual position. It has been suggested that mental processes derived from a number of invariant and noninvariant principles produce the mislocalization in memory. In this study, the effects of velocity, expectation, friction, memory averaging, and weight were reconsidered, and evidence was accumulated that supports the alternative view that the distortions arise to a large degree at a perceptual level. Effects of velocity and expectation were present when observers still perceived a persisting image of the target. It is suggested that the active reorienting of the perceptual organs explains the distortions. Furthermore, distortions of the perceived center of a visible stimulus may explain effects that have previously been attributed to memory averaging and mental analogues of weight. Thus, the locus of memory displacement is at least partially perceptual.     

On the flexibility and the fallibility of associative memory

We report the results of four experiments in which we explored the flexibility and fallibility of associative recognition memory. In each experiment, pairs were studied one or more times, and the task was to discriminate intact from rearranged pairs. The critical findings are that the pattern of false alarm rates was dependent on the nature of the recognition procedure (e.g., ratings vs. yes-no) and the situation in which the task was performed. The specific pattern of findings suggest that subjects adopt different recognition strategies in order to achieve a desired level of performance in the most efficient manner possible by varying the degree to which they base their decisions on familiarity versus recollected information. Implications for theories of recognition memory are discussed.