Impact of encoding depth on awareness of perceptual effects in recognition memory

Pictorial stimuli are more likely to be recognized if they are the same size, rather than a different size, at study and at test. This size congruency effect was replicated in two experiments in which the encoding variables were respectively undivided versus divided attention and level of processing. In terms of performance, these variables influenced recognition and did not influence size congruency effects. But in terms of awareness, measured by remember and know responses, these variables did influence size congruency effects. With undivided attention and with a deep level of processing, size congruency effects occurred only in remembering. With divided attention and with a shallow level of processing, size congruency effects occurred only in knowing. The results show that effects that occur in remembering may also occur independently in knowing. They support theories in which remembering and knowing reflect different memory processes or systems. They do not support the theory that remembering and knowing reflect differences in trace strength.     

Perceptual effects and recollective experience in face recognition

Four experiments were conducted investigating the effect of size congruency on facial recognition memory, measured by remember, know and guess responses. Different study times were employed, that is extremely short (300 and 700 ms), short (1,000 ms), and long times (5,000 ms). With the short study time (1,000 ms) size congruency occurred in knowing. With the long study time the effect of size congruency occurred in remembering. These results support the distinctiveness/ fluency account of remembering and knowing as well as the memory systems account, since the size congruency effect that occurred in knowing under conditions that facilitated perceptual fluency also occurred independently in remembering under conditions that facilitated elaborative encoding. They do not support the idea that remember and know responses reflect differences in trace strength.     

Transferring voice effects in recognition memory from remembering to knowing

In five experiments, we investigated the effects of voice congruency (same vs. different voices at study and at test) on remembering and knowing in recognition memory. With low- and medium-frequency three- or four-syllable words, a voice congruency effect occurred only in remembering. With nonwords, voice congruency effects occurred both in remembering and in knowing. With nonwords and divided attention at study, the voice congruency effect transferred almost completely from remembering to knowing. By showing a transfer of effects from remembering to knowing as encoding became more impoverished, these findings support a distinctiveness/fluency account of remembering and knowing as well as the theory that remembering and knowing indicate retrieval of events from episodic and semantic memory systems, respectively.     

Recognition memory and awareness: Occurrence of perceptual effects in remembering or in knowing depends on conscious resources at encoding, but not at retrieval

We report four experiments in which a remember-know paradigm was combined with a response deadline procedure in order to assess memory awareness in fast, as compared with slow,recognition judgments. In the experiments, we also investigated the perceptual effects of study-test congruence, either for picture size or for speaker's voice, following either full or divided attention at study. These perceptual effects occurred in remembering with full attention and in knowing with divided attention, but they were uninfluenced by recognition speed, indicating that their occurrence in remembering or knowing depends more on conscious resources at encoding than on those at retrieval. The results have implications for theoretical accounts of remembering and knowing that assume that remembering is more consciously controlled and effortful, whereas knowing is more automatic and faster.     

Conscious control and memory awareness when recognising famous faces

We describe an experiment that investigated levels-of-processing effects in recognition memory for famous faces. The degree of conscious control over the recognition decisions was manipulated by using a response deadline procedure, and memory awareness associated with those decisions was assessed using a standard remember-know paradigm. Levels-of-processing effects were found at both short and long response deadlines, and at both deadlines those effects occurred only in remembering. Moreover, knowing, as well as remembering, increased with the greater opportunity for conscious control over recognition decisions at the long deadline. These results have implications for dual-process theories that distinguish between a slower, more controlled recollection process, reflected in remembering, and a faster, more automatic familiarity process, reflected in knowing.     

Conscious control and memory awareness when recognising famous faces

We describe an experiment that investigated levels-of-processing effects in recognition memory for famous faces. The degree of conscious control over the recognition decisions was manipulated by using a response deadline procedure, and memory awareness associated with those decisions was assessed using a standard remember-know paradigm. Levels-of-processing effects were found at both short and long response deadlines, and at both deadlines those effects occurred only in remembering. Moreover, knowing, as well as remembering, increased with the greater opportunity for conscious control over recognition decisions at the long deadline. These results have implications for dual-process theories that distinguish between a slower, more controlled recollection process, reflected in remembering, and a faster, more automatic familiarity process, reflected in knowing.     

Effects of exact and category repetition in true and false recognition memory

Two experiments used the distinction between remembering and knowing to investigate the effects of exact and category repetition in recognition memory. In Experiment 1, exact repetition enhanced remember responses but had no reliable effect on know responses. In Experiment 2, category repetition enhanced correct know responses but had no effect on correct remember responses. Category repetition also increased false positive remember and know responses. It is argued that exact repetition influences the recollection component of recognition memory via the creation of multiple episodic traces, each of which is potentially capable of supporting a remember response, whereas category repetition influences the familiarity component of recognition memory by enhancing the fluency with which test items are processed.     

Dissociative effects of alcohol on recollective experience

This article reports a study comparing the effects of a single dose of alcohol with a matched placebo drink on recognition memory with and without conscious recollection. A double-blind, cross-over design was used with healthy volunteers who were all social drinkers. Processing depth at study was manipulated using generate versus read instructions. Conscious recollection at test was assessed using the remember-know-guess paradigm (Gardiner, 1988; Tulving, 1985). Alcohol significantly reduced conscious recollection (remember responses) but had no effect on recognition in the absence of conscious recollection (know responses). False alarms rates were low and unaffected by alcohol. Previous findings that generation effects are found only for remember responses were closely replicated. A further dissociation of the generation effect occurred between treatments in that deeper processing at study facilitated recognition on placebo but not on alcohol. That both alcohol and depth of processing produce dissociative effects on recollective experience provides further evidence that remembering and knowing reflect distinct memory systems.     

Recognition memory performance as a function of reported subjective awareness

Three experiments introduced a recognition memory paradigm designed to investigate reported subjective awareness during retrieval. At study, in Experiments 1A and 2, words were either generated or read (generation), while modality of presentation (auditory versus visual) was manipulated in Experiment 1B. Word pairs (old/new or new/new) were presented during test trials, and participants indicated if they contained an old word by responding "remember", "know" or "new" in Experiments 1A and 1B, and by responding "strong no", "weak no", "weak yes", or "strong yes" in Experiment 2. Participants were then required to decide which of the 2 words was old. We demonstrated that the proportion measures used in the Remember Know paradigm substantially underestimated the influence of generation on familiarity resulting in an artificial dissociation between indices of knowing (familiarity) and remembering (recollection). We also found a qualitatively different pattern of forced-choice recognition performance as a function of claimed awareness.     

The effect of prior experience on recognition thresholds for plane-disoriented pictures of familiar objects

We investigated plane rotation effects on the minimum presentation duration that is required in order to recognize pictures of familiar objects, using the method of ascending limits. Subjects made unspeeded verification responses, selecting from 126 written alternatives. Replicating similar identification studies in which brief, masked pictures (Lawson & Jolicoeur, 1998) were presented, disorientation reduced the efficiency of recognition. Mirroring the findings in speeded picture naming studies (e.g., Jolicoeur, 1985; Jolicoeur & Milliken, 1989), but in contrast to those of Lawson and Jolicoeur (1998), orientation effects were found over a wide range of views and were attenuated but not eliminated with experience with a given object. The results bridge the findings from unspeeded verification and speeded naming tasks. They suggest that the same orientation-sensitive processes are tapped in both cases, and that practice effects on these processes are object specific.     

The role of decision processes in remembering and knowing

Participants in recognition memory studies are now often asked to partition recognized items into ones that are accompanied by some recollective experience (those they remember) and ones that are not so accompanied (but which they know were previously encountered). Rather than detecting separate memory systems, such attempts to distinguish between remembering and knowing are better understood as a division of positive recognition responses into those that lie above a second decision criterion (remember) and those that do not (know). As such, the amount of memory associated with knowing is strongly dependent on the placement of the decision criteria. A meta-analysis of published data and a simple experiment tested predictions from the decision process analysis of remember/know responses.     

When hearing the bark helps to identify the dog: Semantically-congruent sounds modulate the identification of masked pictures

We report a series of experiments designed to assess the effect of audiovisual semantic congruency on the identification of visually-presented pictures. Participants made unspeeded identification responses concerning a series of briefly-presented, and then rapidly-masked, pictures. A naturalistic sound was sometimes presented together with the picture at a stimulus onset asynchrony (SOA) that varied between 0 and 533 ms (auditory lagging). The sound could be semantically congruent, semantically incongruent, or else neutral (white noise) with respect to the target picture. The results showed that when the onset of the picture and sound occurred simultaneously, a semantically-congruent sound improved, whereas a semantically-incongruent sound impaired, participants’ picture identification performance, as compared to performance in the white-noise control condition. A significant facilitatory effect was also observed at SOAs of around 300 ms, whereas no such semantic congruency effects were observed at the longest interval (533 ms). These results therefore suggest that the neural representations associated with visual and auditory stimuli can interact in a shared semantic system. Furthermore, this crossmodal semantic interaction is not constrained by the need for the strict temporal coincidence of the constituent auditory and visual stimuli. We therefore suggest that audiovisual semantic interactions likely occur in a short-term buffer which rapidly accesses, and temporarily retains, the semantic representations of multisensory stimuli in order to form a coherent multisensory object representation. These results are explained in terms of Potter’s (1993) notion of conceptual short-term memory.     

Subjective qualities of memories associated with the picture superiority effect in schizophrenia

Patients with schizophrenia (n = 24) matched with 24 normal subjects were presented with both words and pictures. On a recognition memory task, they were asked to give remember, know, or guess responses to items that were recognized on the basis of conscious recollection, familiarity, or guessing, respectively. Compared with normal subjects, patients exhibited a lower picture superiority effect selectively related to remember responses. Unlike normal subjects, they did not exhibit any word superiority effect in relation to guess responses; this explains why the overall picture superiority effect appeared to be intact. These results emphasize the need to take into account the subjective states of awareness when analyzing memory impairments in schizophrenia.     

Investigating the attentional demands of recognition memory: Manipulating depth of encoding at study and level of attention at test

Two experiments investigated the effects of divided attention at test after manipulating levels of processing at study. In Experiment 1 items were studied either intact or as anagrams. In Experiment 2 items were studied with either full or divided attention (DA). In both experiments participants carried out a recognition test with either full or divided attention. Analysis of remember and know responses revealed that DA at test had no effect on remember responses to anagrams or to items studied with full attention. In contrast, Know responses decreased with DA at test, and this occurred for items studied in both deep and shallow encoding conditions. The present study confirms recent findings (Knott & Dewhurst, 2007a) that knowing can rely on more controlled retrieval processes, whereas remembering can rely on more automatic retrieval processes. Differences in the controlled processes associated with recollection and familiarity and remember and know responses are discussed.     

Clinical and non-clinical hallucinations are similarly associated with source memory errors in a visual memory task

Hallucinations have been found to be associated with various types of source memory failure in both schizophrenia patients and hallucination-prone healthy individuals. We investigated the associations of clinical and non-clinical hallucinations with source memory errors in a visual memory task that involved the remembering of picture presentation context. 59 schizophrenia patients and 61 healthy individuals took part in the study. Pictures were presented either at different locations or in association with different visual stimuli. The participants were required afterwards to recognize the target pictures among distractors, and then to remember their spatial location or the visual stimulus that was associated with them. Liberal response bias in picture recognition was associated with hallucination proneness and auditory-verbal hallucinations in subsamples of participants with significant non-clinical or clinical hallucinations. After controlling for overall memory performance, failure to remember the spatial location of the pictures was associated with visual hallucinations in male patients; failure to remember the associated visual stimulus was related to auditory-verbal hallucinations in female patients and to hallucination proneness in healthy women. The findings suggest that both clinical and non-clinical hallucinations are associated with loss of contextual information relative to the acquisition of events.     

The effects of plane rotation on the recognition of brief masked pictures of familiar objects

Two experiments examined the effects of plane rotation on the recognition of briefly displayed pictures of familiar objects, using a picture—word verification task. Mirroring the results of earlier picture naming studies (Jolicoeur, 1985; Jolicoeur & Milliken, 1989), plane rotation away from a canonical upright orientation reduced the efficiency of recognition, although in contrast to the results from picture naming studies, the rotation effects were not reduced with experience with the stimuli. However, the rotation effects were influenced by the visual similarity of the distractor objects to the picture of the object presented, with greater orientation sensitivity being observed when visually similar distractors were presented. We suggest that subjects use orientation-sensitive representations to recognize objects in both the present unspeeded verification and in the earlier speeded naming tests of picture identification.     

Mine to remember: The impact of ownership on recollective experience

Evaluating information with reference to self is associated with enhanced memory, the “self-reference effect”. The effect is found in recognition accompanied by recollective experience (remembering), but not in recognition based on a feeling of knowing. The current research employed an ownership procedure to investigate whether less evaluative forms of self-referential cognition produce similar enhancement of recollective experience. Participants were asked to sort items into baskets that belonged to themselves or a fictitious other. A subsequent remember–know recognition test showed that items encoded in the context of self-ownership were more likely to be correctly recognized than other-owned items. This ownership effect was found in remember, but not know, responses. This finding suggests that creating a self-referential encoding context leads to elaborative representations in episodic memory, even in the absence of explicit self-evaluation.     

Repetition of previously novel melodies sometimes increases both remember and know responses in recognition memory

Recognition memory for previously novel melodies was tested in three experiments in which subjects usedremember andknow responses to report experiences of recollection, or of familiarity in the absence of recollection, for each melody they recognized. Some of the melodies were taken from Polish folk songs and presented vocally, but without the words. Others were taken from obscure pieces of classical music, presented as single-line melodies. Prior to the test, the melodies were repeated for varying numbers of study trials. Repetition of the Polish melodies increased both remember and know responses, while repetition of classical melodies increased remember but not know responses. When subjects were instructed to report guesses, guess responses were inversely related to remember and know responses and there were more guesses to lures than to targets. These findings establish that remembering and knowing are fully independent functionally and, by the same token, they provide further evidence against the idea that response exclusivity causes increases in remembering to force decreases in knowing. The findings also suggest that simultaneous increases in remembering and knowing occurred because the Polish melodies came from a genre for which the subjects had relatively little previous experience.     

Recognition memory and introspective remember/know judgments: Evidence for the influence of distractor plausibility on “remembering” and a caution about purportedly nonparametric measures

One popular technique in the study of human recognition memory involves the elicitation of remember and know judgments and the attribution of those judgments to qualitative states of memory retrieval. An alternative view, reviewed here, implicates quantitative, but not qualitative, differences in evidence as the basis for those two judgments. That theory makes two clear and testable predictions: that of criterion shifts in "remembering" and that of isodiscriminability across different response sets. In this experiment, the makeup of the distractor set in a recognition test is shown to influence overall recognition criterion and also rates of "remember" responses. The second portion of the article demonstrates how A' is a poor choice of a measure to test the prediction of isodiscriminability. When this measure is corrected (Equation 7) to make it more consistent with current knowledge about the receiver-operating characteristic in recognition memory, it reveals that there is no difference in discriminability between "remember" and all positive responses.     

PTSD psychiatric patients exhibit a deficit in remembering

This study investigated the effects of PTSD on levels of awareness in a recognition memory task. A group of PTSD psychiatric patients and a control group without any traumatic experience were compared in remembering (R) versus knowing (K) recognition using non-trauma-related words. Results showed that overall recognition did not differ between the two groups, but in the PTSD group a significantly different pattern of Remember and Know responses was produced, indicating a shift from remembering to knowing. However, this shift from remembering to knowing in individuals with PTSD is associated with modifications in the trait anxiety level. These results are interpreted within theoretical frameworks in which R responses could be associated with distinctiveness (Rajaram, 1996) and conceptual processing (Ehlers & Clark, 2000). These collective findings would suggest the possibility that a poor general ability in the formation of source memory may eventually be a common characteristic across different types of PTSD.